Making DefaultDisplayTemplates and DefaultEditorTemplates use IHtmlContent.

- Making TagBuilder's InnerHtml an IHtmlContent.
- Delay encoding until the content is written.
- Moving BufferedHtmlContent to Common cos it is used in aspnet/Razor also.
- Changing GenerateOption to take in a string and create StringHtmlContent.
- This reduces the space used by around 13%.

src/Microsoft.AspNet.Mvc.TagHelpers/InputTagHelper.cs

@@ -249,12 +249,12 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 output.Attributes.Clear();
                 output.TagName = null;
 
-                output.Content.Append(tagBuilder.ToString(TagRenderMode.SelfClosing));
+                output.Content.Append(tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing));
 
                 tagBuilder = Generator.GenerateHiddenForCheckbox(ViewContext, modelExplorer, For.Name);
                 if (tagBuilder != null)
                 {
-                    output.Content.Append(tagBuilder.ToString(TagRenderMode.SelfClosing));
+                    output.Content.Append(tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing));
                 }
             }
         }

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/BufferedHtmlContent.cs

@@ -1,113 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System;
-using System.Collections.Generic;
-using System.IO;
-using Microsoft.AspNet.Html.Abstractions;
-using Microsoft.Framework.Internal;
-using Microsoft.Framework.WebEncoders;
-
-namespace Microsoft.AspNet.Mvc.Rendering
-{
-    /// <summary>
-    /// Enumerable object collection which knows how to write itself.
-    /// </summary>
-    public class BufferedHtmlContent : IHtmlContent
-    {
-        private const int MaxCharToStringLength = 1024;
-        // This is not List<IHtmlContent> because that would lead to boxing all strings to IHtmlContent
-        // which is not space performant.
-        // internal for testing.
-        internal List<object> Entries { get; } = new List<object>();
-
-        /// <summary>
-        /// Appends the string to the collection.
-        /// </summary>
-        /// <param name="value">The <c>string</c> to be appended.</param>
-        public void Append([NotNull] string value)
-        {
-            Entries.Add(value);
-        }
-
-        /// <summary>
-        /// Appends a character array to the collection.
-        /// </summary>
-        /// <param name="value">The character array to be appended.</param>
-        /// <param name="index">The index from which the character array must be read.</param>
-        /// <param name="count">The count till which the character array must be read.</param>
-        /// <remarks>
-        /// Splits the character array into strings of 1KB length and appends them.
-        /// </remarks>
-        public void Append([NotNull] char[] value, int index, int count)
-        {
-            if (index < 0)
-            {
-                throw new ArgumentOutOfRangeException(nameof(index));
-            }
-            if (count < 0 || value.Length - index < count)
-            {
-                throw new ArgumentOutOfRangeException(nameof(count));
-            }
-
-            while (count > 0)
-            {
-                // Split large char arrays into 1KB strings.
-                var currentCount = count;
-                if (MaxCharToStringLength < currentCount)
-                {
-                    currentCount = MaxCharToStringLength;
-                }
-
-                Append(new string(value, index, currentCount));
-                index += currentCount;
-                count -= currentCount;
-            }
-        }
-
-        /// <summary>
-        /// Appends a <see cref="IHtmlContent"/> to the collection.
-        /// </summary>
-        /// <param name="htmlContent">The <see cref="IHtmlContent"/> to be appended.</param>
-        public void Append([NotNull] IHtmlContent htmlContent)
-        {
-            Entries.Add(htmlContent);
-        }
-
-        /// <summary>
-        /// Removes all the entries from the collection.
-        /// </summary>
-        public void Clear()
-        {
-            Entries.Clear();
-        }
-
-        /// <inheritdoc />
-        public void WriteTo([NotNull] TextWriter writer, [NotNull] IHtmlEncoder encoder)
-        {
-            foreach (var entry in Entries)
-            {
-                var entryAsString = entry as string;
-                if (entryAsString != null)
-                {
-                    writer.Write(entryAsString);
-                }
-                else
-                {
-                    // Only string, IHtmlContent values can be added to the buffer.
-                    ((IHtmlContent)entry).WriteTo(writer, encoder);
-                }
-            }
-        }
-
-        /// <inheritdoc />
-        public override string ToString()
-        {
-            using (var writer = new StringWriter())
-            {
-                WriteTo(writer, new HtmlEncoder());
-                return writer.ToString();
-            }
-        }
-    }
-}

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Html/DefaultDisplayTemplates.cs

@@ -6,17 +6,18 @@ using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
-using System.Text;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering.Internal;
 using Microsoft.AspNet.Mvc.ViewFeatures;
 using Microsoft.Framework.DependencyInjection;
+using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
 {
     public static class DefaultDisplayTemplates
     {
-        public static string BooleanTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent BooleanTemplate(IHtmlHelper htmlHelper)
         {
             bool? value = null;
             if (htmlHelper.ViewData.Model != null)
@@ -29,9 +30,9 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 BooleanTemplateCheckbox(value ?? false, htmlHelper);
         }
 
-        private static string BooleanTemplateCheckbox(bool value, IHtmlHelper htmlHelper)
+        private static IHtmlContent BooleanTemplateCheckbox(bool value, IHtmlHelper htmlHelper)
         {
-            var inputTag = new TagBuilder("input", htmlHelper.HtmlEncoder);
+            var inputTag = new TagBuilder("input");
             inputTag.AddCssClass("check-box");
             inputTag.Attributes["disabled"] = "disabled";
             inputTag.Attributes["type"] = "checkbox";
@@ -40,28 +41,28 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 inputTag.Attributes["checked"] = "checked";
             }
 
-            return inputTag.ToString(TagRenderMode.SelfClosing);
+            return inputTag.ToHtmlContent(TagRenderMode.SelfClosing);
         }
 
-        private static string BooleanTemplateDropDownList(IHtmlHelper htmlHelper, bool? value)
+        private static IHtmlContent BooleanTemplateDropDownList(IHtmlHelper htmlHelper, bool? value)
         {
-            var selectTag = new TagBuilder("select", htmlHelper.HtmlEncoder);
+            var selectTag = new TagBuilder("select");
             selectTag.AddCssClass("list-box");
             selectTag.AddCssClass("tri-state");
             selectTag.Attributes["disabled"] = "disabled";
 
-            var builder = new StringBuilder();
-            builder.Append(selectTag.ToString(TagRenderMode.StartTag));
+            var content = new BufferedHtmlContent();
+            content.Append(selectTag.ToHtmlContent(TagRenderMode.StartTag));
 
             foreach (var item in TriStateValues(value))
             {
-                var encodedText = htmlHelper.Encode(item.Text);
-                var option = DefaultHtmlGenerator.GenerateOption(item, encodedText, htmlHelper.HtmlEncoder);
-                builder.Append(option);
+                content.Append(
+                    DefaultHtmlGenerator.GenerateOption(item, item.Text)
+                        .ToHtmlContent(TagRenderMode.Normal));
             }
 
-            builder.Append(selectTag.ToString(TagRenderMode.EndTag));
-            return builder.ToString();
+            content.Append(selectTag.ToHtmlContent(TagRenderMode.EndTag));
+            return content;
         }
 
         // Will soon need to be shared with the default editor templates implementations.
@@ -90,12 +91,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
             };
         }
 
-        public static string CollectionTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent CollectionTemplate(IHtmlHelper htmlHelper)
         {
             var model = htmlHelper.ViewData.Model;
             if (model == null)
             {
-                return string.Empty;
+                return HtmlString.Empty;
             }
 
             var collection = model as IEnumerable;
@@ -125,7 +126,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlHelper.ViewData.TemplateInfo.HtmlFieldPrefix = string.Empty;
 
                 var fieldNameBase = oldPrefix;
-                var result = new StringBuilder();
+                var result = new BufferedHtmlContent();
                 var viewEngine = serviceProvider.GetRequiredService<ICompositeViewEngine>();
 
                 var index = 0;
@@ -153,12 +154,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                         templateName: null,
                         readOnly: true,
                         additionalViewData: null);
-
-                    var output = templateBuilder.Build();
-                    result.Append(output);
+                    result.Append(templateBuilder.Build());
                 }
 
-                return result.ToString();
+                return result;
             }
             finally
             {
@@ -166,7 +165,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
         }
 
-        public static string DecimalTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent DecimalTemplate(IHtmlHelper htmlHelper)
         {
             if (htmlHelper.ViewData.TemplateInfo.FormattedModelValue == htmlHelper.ViewData.Model)
             {
@@ -177,7 +176,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return StringTemplate(htmlHelper);
         }
 
-        public static string EmailAddressTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent EmailAddressTemplate(IHtmlHelper htmlHelper)
         {
             var uriString = "mailto:" + ((htmlHelper.ViewData.Model == null) ?
                 string.Empty :
@@ -189,31 +188,31 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return HyperlinkTemplate(uriString, linkedText, htmlHelper);
         }
 
-        public static string HiddenInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent HiddenInputTemplate(IHtmlHelper htmlHelper)
         {
             if (htmlHelper.ViewData.ModelMetadata.HideSurroundingHtml)
             {
-                return string.Empty;
+                return HtmlString.Empty;
             }
 
             return StringTemplate(htmlHelper);
         }
 
-        public static string HtmlTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent HtmlTemplate(IHtmlHelper htmlHelper)
         {
-            return htmlHelper.ViewData.TemplateInfo.FormattedModelValue.ToString();
+            return new HtmlString(htmlHelper.ViewData.TemplateInfo.FormattedModelValue.ToString());
         }
 
-        public static string ObjectTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent ObjectTemplate(IHtmlHelper htmlHelper)
         {
             var viewData = htmlHelper.ViewData;
             var templateInfo = viewData.TemplateInfo;
             var modelExplorer = viewData.ModelExplorer;
-            var builder = new StringBuilder();
+            var content = new BufferedHtmlContent();
 
             if (modelExplorer.Model == null)
             {
-                return modelExplorer.Metadata.NullDisplayText;
+                return new HtmlString(modelExplorer.Metadata.NullDisplayText);
             }
 
             if (templateInfo.TemplateDepth > 1)
@@ -224,7 +223,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     text = htmlHelper.Encode(text);
                 }
 
-                return text;
+                return new HtmlString(text);
             }
 
             var serviceProvider = htmlHelper.ViewContext.HttpContext.RequestServices;
@@ -238,7 +237,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     continue;
                 }
 
-                var divTag = new TagBuilder("div", htmlHelper.HtmlEncoder);
+                var divTag = new TagBuilder("div");
 
                 if (!propertyMetadata.HideSurroundingHtml)
                 {
@@ -247,14 +246,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     {
                         divTag.SetInnerText(label);
                         divTag.AddCssClass("display-label");
-                        builder.AppendLine(divTag.ToString(TagRenderMode.Normal));
+                        content.AppendLine(divTag.ToHtmlContent(TagRenderMode.Normal));
 
                         // Reset divTag for reuse.
                         divTag.Attributes.Clear();
                     }
 
                     divTag.AddCssClass("display-field");
-                    builder.Append(divTag.ToString(TagRenderMode.StartTag));
+                    content.Append(divTag.ToHtmlContent(TagRenderMode.StartTag));
                 }
 
                 var templateBuilder = new TemplateBuilder(
@@ -267,15 +266,15 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     readOnly: true,
                     additionalViewData: null);
 
-                builder.Append(templateBuilder.Build());
+                content.Append(templateBuilder.Build());
 
                 if (!propertyMetadata.HideSurroundingHtml)
                 {
-                    builder.AppendLine(divTag.ToString(TagRenderMode.EndTag));
+                    content.AppendLine(divTag.ToHtmlContent(TagRenderMode.EndTag));
                 }
             }
 
-            return builder.ToString();
+            return content;
         }
 
         private static bool ShouldShow(ModelExplorer modelExplorer, TemplateInfo templateInfo)
@@ -286,12 +285,18 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 !templateInfo.Visited(modelExplorer);
         }
 
-        public static string StringTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent StringTemplate(IHtmlHelper htmlHelper)
         {
-            return htmlHelper.Encode(htmlHelper.ViewData.TemplateInfo.FormattedModelValue);
+            var value = htmlHelper.ViewData.TemplateInfo.FormattedModelValue;
+            if (value == null)
+            {
+                return HtmlString.Empty;
+            }
+
+            return new StringHtmlContent(value.ToString());
         }
 
-        public static string UrlTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent UrlTemplate(IHtmlHelper htmlHelper)
         {
             var uriString = (htmlHelper.ViewData.Model == null) ? string.Empty : htmlHelper.ViewData.Model.ToString();
             var linkedText = (htmlHelper.ViewData.TemplateInfo.FormattedModelValue == null) ?
@@ -302,13 +307,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         // Neither uriString nor linkedText need be encoded prior to calling this method.
-        private static string HyperlinkTemplate(string uriString, string linkedText, IHtmlHelper htmlHelper)
+        private static IHtmlContent HyperlinkTemplate(string uriString, string linkedText, IHtmlHelper htmlHelper)
         {
-            var hyperlinkTag = new TagBuilder("a", htmlHelper.HtmlEncoder);
+            var hyperlinkTag = new TagBuilder("a");
             hyperlinkTag.MergeAttribute("href", uriString);
             hyperlinkTag.SetInnerText(linkedText);
 
-            return hyperlinkTag.ToString(TagRenderMode.Normal);
+            return hyperlinkTag.ToHtmlContent(TagRenderMode.Normal);
         }
     }
 }

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Html/DefaultEditorTemplates.cs

@@ -7,6 +7,7 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
 using System.Text;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering.Internal;
 using Microsoft.AspNet.Mvc.ViewFeatures;
@@ -19,7 +20,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
     {
         private const string HtmlAttributeKey = "htmlAttributes";
 
-        public static string BooleanTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent BooleanTemplate(IHtmlHelper htmlHelper)
         {
             bool? value = null;
             if (htmlHelper.ViewData.Model != null)
@@ -32,32 +33,30 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 BooleanTemplateCheckbox(htmlHelper, value ?? false);
         }
 
-        private static string BooleanTemplateCheckbox(IHtmlHelper htmlHelper, bool value)
+        private static IHtmlContent BooleanTemplateCheckbox(IHtmlHelper htmlHelper, bool value)
         {
             return htmlHelper.CheckBox(
                 expression: null,
                 isChecked: value,
-                htmlAttributes: CreateHtmlAttributes(htmlHelper, "check-box"))
-                    .ToString();
+                htmlAttributes: CreateHtmlAttributes(htmlHelper, "check-box"));
         }
 
-        private static string BooleanTemplateDropDownList(IHtmlHelper htmlHelper, bool? value)
+        private static IHtmlContent BooleanTemplateDropDownList(IHtmlHelper htmlHelper, bool? value)
         {
             return htmlHelper.DropDownList(
                 expression: null,
                 selectList: DefaultDisplayTemplates.TriStateValues(value),
                 optionLabel: null,
-                htmlAttributes: CreateHtmlAttributes(htmlHelper, "list-box tri-state"))
-                    .ToString();
+                htmlAttributes: CreateHtmlAttributes(htmlHelper, "list-box tri-state"));
         }
 
-        public static string CollectionTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent CollectionTemplate(IHtmlHelper htmlHelper)
         {
             var viewData = htmlHelper.ViewData;
             var model = viewData.Model;
             if (model == null)
             {
-                return string.Empty;
+                return HtmlString.Empty;
             }
 
             var collection = model as IEnumerable;
@@ -87,7 +86,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 viewData.TemplateInfo.HtmlFieldPrefix = string.Empty;
 
                 var fieldNameBase = oldPrefix;
-                var result = new StringBuilder();
+                var result = new BufferedHtmlContent();
                 var viewEngine = serviceProvider.GetRequiredService<ICompositeViewEngine>();
 
                 var index = 0;
@@ -115,12 +114,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                         templateName: null,
                         readOnly: false,
                         additionalViewData: null);
-
-                    var output = templateBuilder.Build();
-                    result.Append(output);
+                    result.Append(templateBuilder.Build());
                 }
 
-                return result.ToString();
+                return result;
             }
             finally
             {
@@ -128,7 +125,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
         }
 
-        public static string DecimalTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent DecimalTemplate(IHtmlHelper htmlHelper)
         {
             if (htmlHelper.ViewData.TemplateInfo.FormattedModelValue == htmlHelper.ViewData.Model)
             {
@@ -139,19 +136,15 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return StringTemplate(htmlHelper);
         }
 
-        public static string HiddenInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent HiddenInputTemplate(IHtmlHelper htmlHelper)
         {
             var viewData = htmlHelper.ViewData;
             var model = viewData.Model;
 
-            string result;
-            if (viewData.ModelMetadata.HideSurroundingHtml)
+            var result = new BufferedHtmlContent();
+            if (!viewData.ModelMetadata.HideSurroundingHtml)
             {
-                result = string.Empty;
-            }
-            else
-            {
-                result = DefaultDisplayTemplates.StringTemplate(htmlHelper);
+                result.Append(DefaultDisplayTemplates.StringTemplate(htmlHelper));
             }
 
             // Special-case opaque values and arbitrary binary data.
@@ -163,7 +156,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
             var htmlAttributesObject = viewData[HtmlAttributeKey];
             var hiddenResult = htmlHelper.Hidden(expression: null, value: model, htmlAttributes: htmlAttributesObject);
-            result += hiddenResult.ToString();
+            result.Append(hiddenResult);
 
             return result;
         }
@@ -219,43 +212,42 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return htmlAttributes;
         }
 
-        public static string MultilineTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent MultilineTemplate(IHtmlHelper htmlHelper)
         {
-            var htmlString = htmlHelper.TextArea(
+            return htmlHelper.TextArea(
                 expression: string.Empty,
                 value: htmlHelper.ViewContext.ViewData.TemplateInfo.FormattedModelValue.ToString(),
                 rows: 0,
                 columns: 0,
                 htmlAttributes: CreateHtmlAttributes(htmlHelper, "text-box multi-line"));
-            return htmlString.ToString();
         }
 
-        public static string ObjectTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent ObjectTemplate(IHtmlHelper htmlHelper)
         {
             var viewData = htmlHelper.ViewData;
             var templateInfo = viewData.TemplateInfo;
             var modelExplorer = viewData.ModelExplorer;
-            var builder = new StringBuilder();
 
             if (templateInfo.TemplateDepth > 1)
             {
                 if (modelExplorer.Model == null)
                 {
-                    return modelExplorer.Metadata.NullDisplayText;
+                    return new HtmlString(modelExplorer.Metadata.NullDisplayText);
                 }
 
                 var text = modelExplorer.GetSimpleDisplayText();
                 if (modelExplorer.Metadata.HtmlEncode)
                 {
-                    text = htmlHelper.Encode(text);
+                    return new StringHtmlContent(text);
                 }
 
-                return text;
+                return new HtmlString(text);
             }
 
             var serviceProvider = htmlHelper.ViewContext.HttpContext.RequestServices;
             var viewEngine = serviceProvider.GetRequiredService<ICompositeViewEngine>();
 
+            var content = new BufferedHtmlContent();
             foreach (var propertyExplorer in modelExplorer.Properties)
             {
                 var propertyMetadata = propertyExplorer.Metadata;
@@ -264,27 +256,26 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     continue;
                 }
 
-                var divTag = new TagBuilder("div", htmlHelper.HtmlEncoder);
+                var divTag = new TagBuilder("div");
 
                 if (!propertyMetadata.HideSurroundingHtml)
                 {
                     var label = htmlHelper.Label(
                         propertyMetadata.PropertyName,
                         labelText: null,
-                        htmlAttributes: null)
-                            .ToString();
-                    if (!string.IsNullOrEmpty(label))
+                        htmlAttributes: null);
+                    if (!string.IsNullOrEmpty(label.ToString()))
                     {
                         divTag.AddCssClass("editor-label");
                         divTag.InnerHtml = label; // already escaped
-                        builder.AppendLine(divTag.ToString(TagRenderMode.Normal));
+                        content.AppendLine(divTag.ToHtmlContent(TagRenderMode.Normal));
 
                         // Reset divTag for reuse.
                         divTag.Attributes.Clear();
                     }
 
                     divTag.AddCssClass("editor-field");
-                    builder.Append(divTag.ToString(TagRenderMode.StartTag));
+                    content.Append(divTag.ToHtmlContent(TagRenderMode.StartTag));
                 }
 
                 var templateBuilder = new TemplateBuilder(
@@ -297,31 +288,30 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     readOnly: false,
                     additionalViewData: null);
 
-                builder.Append(templateBuilder.Build());
+                content.Append(templateBuilder.Build());
 
                 if (!propertyMetadata.HideSurroundingHtml)
                 {
-                    builder.Append(" ");
-                    builder.Append(htmlHelper.ValidationMessage(
+                    content.Append(" ");
+                    content.Append(htmlHelper.ValidationMessage(
                         propertyMetadata.PropertyName,
                         message: null,
                         htmlAttributes: null,
                         tag: null));
 
-                    builder.AppendLine(divTag.ToString(TagRenderMode.EndTag));
+                    content.AppendLine(divTag.ToHtmlContent(TagRenderMode.EndTag));
                 }
             }
 
-            return builder.ToString();
+            return content;
         }
 
-        public static string PasswordTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent PasswordTemplate(IHtmlHelper htmlHelper)
         {
             return htmlHelper.Password(
                 expression: null,
                 value: htmlHelper.ViewData.TemplateInfo.FormattedModelValue,
-                htmlAttributes: CreateHtmlAttributes(htmlHelper, "text-box single-line password"))
-                    .ToString();
+                htmlAttributes: CreateHtmlAttributes(htmlHelper, "text-box single-line password"));
         }
 
         private static bool ShouldShow(ModelExplorer modelExplorer, TemplateInfo templateInfo)
@@ -332,61 +322,61 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 !templateInfo.Visited(modelExplorer);
         }
 
-        public static string StringTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent StringTemplate(IHtmlHelper htmlHelper)
         {
             return GenerateTextBox(htmlHelper);
         }
 
-        public static string PhoneNumberInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent PhoneNumberInputTemplate(IHtmlHelper htmlHelper)
         {
             return GenerateTextBox(htmlHelper, inputType: "tel");
         }
 
-        public static string UrlInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent UrlInputTemplate(IHtmlHelper htmlHelper)
         {
             return GenerateTextBox(htmlHelper, inputType: "url");
         }
 
-        public static string EmailAddressInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent EmailAddressInputTemplate(IHtmlHelper htmlHelper)
         {
             return GenerateTextBox(htmlHelper, inputType: "email");
         }
 
-        public static string DateTimeInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent DateTimeInputTemplate(IHtmlHelper htmlHelper)
         {
             ApplyRfc3339DateFormattingIfNeeded(htmlHelper, "{0:yyyy-MM-ddTHH:mm:ss.fffK}");
             return GenerateTextBox(htmlHelper, inputType: "datetime");
         }
 
-        public static string DateTimeLocalInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent DateTimeLocalInputTemplate(IHtmlHelper htmlHelper)
         {
             ApplyRfc3339DateFormattingIfNeeded(htmlHelper, "{0:yyyy-MM-ddTHH:mm:ss.fff}");
             return GenerateTextBox(htmlHelper, inputType: "datetime-local");
         }
 
-        public static string DateInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent DateInputTemplate(IHtmlHelper htmlHelper)
         {
             ApplyRfc3339DateFormattingIfNeeded(htmlHelper, "{0:yyyy-MM-dd}");
             return GenerateTextBox(htmlHelper, inputType: "date");
         }
 
-        public static string TimeInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent TimeInputTemplate(IHtmlHelper htmlHelper)
         {
             ApplyRfc3339DateFormattingIfNeeded(htmlHelper, "{0:HH:mm:ss.fff}");
             return GenerateTextBox(htmlHelper, inputType: "time");
         }
 
-        public static string NumberInputTemplate(IHtmlHelper htmlHelper)
+        public static IHtmlContent NumberInputTemplate(IHtmlHelper htmlHelper)
         {
             return GenerateTextBox(htmlHelper, inputType: "number");
         }
 
-        public static string FileInputTemplate([NotNull] IHtmlHelper htmlHelper)
+        public static IHtmlContent FileInputTemplate([NotNull] IHtmlHelper htmlHelper)
         {
             return GenerateTextBox(htmlHelper, inputType: "file");
         }
 
-        public static string FileCollectionInputTemplate([NotNull] IHtmlHelper htmlHelper)
+        public static IHtmlContent FileCollectionInputTemplate([NotNull] IHtmlHelper htmlHelper)
         {
             var htmlAttributes =
                 CreateHtmlAttributes(htmlHelper, className: "text-box single-line", inputType: "file");
@@ -416,12 +406,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
         }
 
-        private static string GenerateTextBox(IHtmlHelper htmlHelper, string inputType = null)
+        private static IHtmlContent GenerateTextBox(IHtmlHelper htmlHelper, string inputType = null)
         {
             return GenerateTextBox(htmlHelper, inputType, htmlHelper.ViewData.TemplateInfo.FormattedModelValue);
         }
 
-        private static string GenerateTextBox(IHtmlHelper htmlHelper, string inputType, object value)
+        private static IHtmlContent GenerateTextBox(IHtmlHelper htmlHelper, string inputType, object value)
         {
             var htmlAttributes =
                 CreateHtmlAttributes(htmlHelper, className: "text-box single-line", inputType: inputType);
@@ -429,14 +419,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return GenerateTextBox(htmlHelper, value, htmlAttributes);
         }
 
-        private static string GenerateTextBox(IHtmlHelper htmlHelper, object value, object htmlAttributes)
+        private static IHtmlContent GenerateTextBox(IHtmlHelper htmlHelper, object value, object htmlAttributes)
         {
             return htmlHelper.TextBox(
                 current: null,
                 value: value,
                 format: null,
-                htmlAttributes: htmlAttributes)
-                    .ToString();
+                htmlAttributes: htmlAttributes);
         }
     }
 }

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Html/DefaultHtmlGenerator.cs

@@ -10,6 +10,7 @@ using System.Linq;
 using System.Reflection;
 using System.Text;
 using Microsoft.AspNet.Antiforgery;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.ModelBinding.Validation;
 using Microsoft.AspNet.Mvc.Rendering.Expressions;
@@ -96,7 +97,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public virtual HtmlString GenerateAntiforgery([NotNull] ViewContext viewContext)
+        public virtual IHtmlContent GenerateAntiforgery([NotNull] ViewContext viewContext)
         {
             var tag = _antiforgery.GetHtml(viewContext.HttpContext);
             return new HtmlString(tag);
@@ -153,7 +154,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             ModelExplorer modelExplorer,
             string expression)
         {
-            var tagBuilder = new TagBuilder("input", _htmlEncoder);
+            var tagBuilder = new TagBuilder("input");
             tagBuilder.MergeAttribute("type", GetInputTypeString(InputType.Hidden));
             tagBuilder.MergeAttribute("value", "false");
 
@@ -266,7 +267,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return null;
             }
 
-            var tagBuilder = new TagBuilder("label", _htmlEncoder);
+            var tagBuilder = new TagBuilder("label");
             var idString =
                 TagBuilder.CreateSanitizedId(GetFullHtmlFieldName(viewContext, expression), IdAttributeDotReplacement);
             tagBuilder.Attributes.Add("for", idString);
@@ -439,9 +440,9 @@ namespace Microsoft.AspNet.Mvc.Rendering
             // Convert each ListItem to an <option> tag and wrap them with <optgroup> if requested.
             var listItemBuilder = GenerateGroupsAndOptions(optionLabel, selectList);
 
-            var tagBuilder = new TagBuilder("select", _htmlEncoder)
+            var tagBuilder = new TagBuilder("select")
             {
-                InnerHtml = listItemBuilder.ToString()
+                InnerHtml = listItemBuilder
             };
             tagBuilder.MergeAttributes(GetHtmlAttributeDictionaryOrNull(htmlAttributes));
             tagBuilder.MergeAttribute("name", fullName, true /* replaceExisting */);
@@ -513,7 +514,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 value = modelExplorer.Model.ToString();
             }
 
-            var tagBuilder = new TagBuilder("textarea", _htmlEncoder);
+            var tagBuilder = new TagBuilder("textarea");
             tagBuilder.GenerateId(fullName, IdAttributeDotReplacement);
             tagBuilder.MergeAttributes(GetHtmlAttributeDictionaryOrNull(htmlAttributes), true);
             if (rows > 0)
@@ -537,7 +538,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
             // The first newline is always trimmed when a TextArea is rendered, so we add an extra one
             // in case the value being rendered is something like "\r\nHello".
-            tagBuilder.InnerHtml = Environment.NewLine + _htmlEncoder.HtmlEncode(value);
+            var innerContent = new BufferedHtmlContent();
+            innerContent.Append(Environment.NewLine);
+            innerContent.Append(new StringHtmlContent(value));
+            tagBuilder.InnerHtml = innerContent;
 
             return tagBuilder;
         }
@@ -614,7 +618,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             {
                 tag = viewContext.ValidationMessageElement;
             }
-            var tagBuilder = new TagBuilder(tag, _htmlEncoder);
+            var tagBuilder = new TagBuilder(tag);
             tagBuilder.MergeAttributes(GetHtmlAttributeDictionaryOrNull(htmlAttributes));
 
             // Only the style of the span is changed according to the errors if message is null or empty.
@@ -660,16 +664,16 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return null;
             }
 
-            string wrappedMessage;
+            var wrappedMessage = new BufferedHtmlContent();
             if (!string.IsNullOrEmpty(message))
             {
                 if (string.IsNullOrEmpty(headerTag))
                 {
                     headerTag = viewContext.ValidationSummaryMessageElement;
                 }
-                var messageTag = new TagBuilder(headerTag, _htmlEncoder);
+                var messageTag = new TagBuilder(headerTag);
                 messageTag.SetInnerText(message);
-                wrappedMessage = messageTag.ToString(TagRenderMode.Normal) + Environment.NewLine;
+                wrappedMessage.AppendLine(messageTag.ToHtmlContent(TagRenderMode.Normal));
             }
             else
             {
@@ -678,7 +682,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
             // If excludePropertyErrors is true, describe any validation issue with the current model in a single item.
             // Otherwise, list individual property errors.
-            var htmlSummary = new StringBuilder();
+            var htmlSummary = new BufferedHtmlContent();
+            var isHtmlSummaryModified = false;
             var modelStates = ValidationHelpers.GetModelStateList(viewContext.ViewData, excludePropertyErrors);
 
             foreach (var modelState in modelStates)
@@ -689,24 +694,25 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
                     if (!string.IsNullOrEmpty(errorText))
                     {
-                        var listItem = new TagBuilder("li", _htmlEncoder);
+                        var listItem = new TagBuilder("li");
                         listItem.SetInnerText(errorText);
-                        htmlSummary.AppendLine(listItem.ToString(TagRenderMode.Normal));
+                        htmlSummary.AppendLine(listItem.ToHtmlContent(TagRenderMode.Normal));
+                        isHtmlSummaryModified = true;
                     }
                 }
             }
 
-            if (htmlSummary.Length == 0)
+            if (!isHtmlSummaryModified)
             {
                 htmlSummary.AppendLine(HiddenListItem);
             }
 
-            var unorderedList = new TagBuilder("ul", _htmlEncoder)
+            var unorderedList = new TagBuilder("ul")
             {
-                InnerHtml = htmlSummary.ToString()
+                InnerHtml = htmlSummary
             };
 
-            var tagBuilder = new TagBuilder("div", _htmlEncoder);
+            var tagBuilder = new TagBuilder("div");
             tagBuilder.MergeAttributes(GetHtmlAttributeDictionaryOrNull(htmlAttributes));
 
             if (viewContext.ViewData.ModelState.IsValid)
@@ -718,7 +724,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 tagBuilder.AddCssClass(HtmlHelper.ValidationSummaryCssClassName);
             }
 
-            tagBuilder.InnerHtml = wrappedMessage + unorderedList.ToString(TagRenderMode.Normal);
+            var innerContent = new BufferedHtmlContent();
+            innerContent.Append(wrappedMessage);
+            innerContent.Append(unorderedList.ToHtmlContent(TagRenderMode.Normal));
+            tagBuilder.InnerHtml = innerContent;
 
             if (formContext != null && !excludePropertyErrors)
             {
@@ -898,12 +907,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <remarks>
         /// Not used directly in HtmlHelper. Exposed for use in DefaultDisplayTemplates.
         /// </remarks>
-        internal static TagBuilder GenerateOption(SelectListItem item, string encodedText, IHtmlEncoder htmlEncoder)
+        internal static TagBuilder GenerateOption(SelectListItem item, string text)
         {
-            var tagBuilder = new TagBuilder("option", htmlEncoder)
-            {
-                InnerHtml = encodedText,
-            };
+            var tagBuilder = new TagBuilder("option");
+            tagBuilder.SetInnerText(text);
 
             if (item.Value != null)
             {
@@ -959,7 +966,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             string method,
             object htmlAttributes)
         {
-            var tagBuilder = new TagBuilder("form", _htmlEncoder);
+            var tagBuilder = new TagBuilder("form");
             tagBuilder.MergeAttributes(GetHtmlAttributeDictionaryOrNull(htmlAttributes));
 
             // action is implicitly generated from other parameters, so htmlAttributes take precedence.
@@ -1007,7 +1014,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     nameof(expression));
             }
 
-            var tagBuilder = new TagBuilder("input", _htmlEncoder);
+            var tagBuilder = new TagBuilder("input");
             tagBuilder.MergeAttributes(htmlAttributes);
             tagBuilder.MergeAttribute("type", GetInputTypeString(inputType));
             tagBuilder.MergeAttribute("name", fullName, replaceExisting: true);
@@ -1108,9 +1115,9 @@ namespace Microsoft.AspNet.Mvc.Rendering
             [NotNull] string url,
             object htmlAttributes)
         {
-            var tagBuilder = new TagBuilder("a", _htmlEncoder)
+            var tagBuilder = new TagBuilder("a")
             {
-                InnerHtml = _htmlEncoder.HtmlEncode(linkText),
+                InnerHtml = new StringHtmlContent(linkText),
             };
 
             tagBuilder.MergeAttributes(GetHtmlAttributeDictionaryOrNull(htmlAttributes));
@@ -1272,9 +1279,9 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return newSelectList;
         }
 
-        private StringBuilder GenerateGroupsAndOptions(string optionLabel, IEnumerable<SelectListItem> selectList)
+        private IHtmlContent GenerateGroupsAndOptions(string optionLabel, IEnumerable<SelectListItem> selectList)
         {
-            var listItemBuilder = new StringBuilder();
+            var listItemBuilder = new BufferedHtmlContent();
 
             // Make optionLabel the first item that gets rendered.
             if (optionLabel != null)
@@ -1300,7 +1307,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 TagBuilder groupBuilder = null;
                 if (optGroup != null)
                 {
-                    groupBuilder = new TagBuilder("optgroup", _htmlEncoder);
+                    groupBuilder = new TagBuilder("optgroup");
                     if (optGroup.Name != null)
                     {
                         groupBuilder.MergeAttribute("label", optGroup.Name);
@@ -1311,7 +1318,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                         groupBuilder.MergeAttribute("disabled", "disabled");
                     }
 
-                    listItemBuilder.AppendLine(groupBuilder.ToString(TagRenderMode.StartTag));
+                    listItemBuilder.AppendLine(groupBuilder.ToHtmlContent(TagRenderMode.StartTag));
                 }
 
                 foreach (var item in group)
@@ -1321,19 +1328,17 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
                 if (optGroup != null)
                 {
-                    listItemBuilder.AppendLine(groupBuilder.ToString(TagRenderMode.EndTag));
+                    listItemBuilder.AppendLine(groupBuilder.ToHtmlContent(TagRenderMode.EndTag));
                 }
             }
 
             return listItemBuilder;
         }
 
-        private string GenerateOption(SelectListItem item)
+        private IHtmlContent GenerateOption(SelectListItem item)
         {
-            var encodedText = Encode(item.Text);
-            var tagBuilder = GenerateOption(item, encodedText, _htmlEncoder);
-
-            return tagBuilder.ToString(TagRenderMode.Normal);
+            var tagBuilder = GenerateOption(item, item.Text);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
     }
 }

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Html/HtmlHelper.cs

@@ -32,6 +32,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
         private readonly IHtmlGenerator _htmlGenerator;
         private readonly ICompositeViewEngine _viewEngine;
+        private readonly IHtmlEncoder _htmlEncoder;
 
         private ViewContext _viewContext;
 
@@ -48,8 +49,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         {
             _viewEngine = viewEngine;
             _htmlGenerator = htmlGenerator;
+            _htmlEncoder = htmlEncoder;
             MetadataProvider = metadataProvider;
-            HtmlEncoder = htmlEncoder;
             UrlEncoder = urlEncoder;
             JavaScriptStringEncoder = javaScriptStringEncoder;
         }
@@ -121,9 +122,6 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
         }
 
-        /// <inheritdoc />
-        public IHtmlEncoder HtmlEncoder { get; }
-
         /// <inheritdoc />
         public IUrlEncoder UrlEncoder { get; }
 
@@ -192,7 +190,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString ActionLink(
+        public IHtmlContent ActionLink(
             [NotNull] string linkText,
             string actionName,
             string controllerName,
@@ -216,11 +214,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.Normal);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
 
         /// <inheritdoc />
-        public HtmlString AntiForgeryToken()
+        public IHtmlContent AntiForgeryToken()
         {
             var html = _htmlGenerator.GenerateAntiforgery(ViewContext);
             return html ?? HtmlString.Empty;
@@ -251,7 +249,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString CheckBox(string expression, bool? isChecked, object htmlAttributes)
+        public IHtmlContent CheckBox(string expression, bool? isChecked, object htmlAttributes)
         {
             return GenerateCheckBox(
                 modelExplorer: null,
@@ -285,7 +283,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString Display(string expression,
+        public IHtmlContent Display(string expression,
                                   string templateName,
                                   string htmlFieldName,
                                   object additionalViewData)
@@ -313,7 +311,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString DropDownList(
+        public IHtmlContent DropDownList(
             string expression,
             IEnumerable<SelectListItem> selectList,
             string optionLabel,
@@ -328,7 +326,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString Editor(
+        public IHtmlContent Editor(
             string expression,
             string templateName,
             string htmlFieldName,
@@ -377,7 +375,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString Hidden(string expression, object value, object htmlAttributes)
+        public IHtmlContent Hidden(string expression, object value, object htmlAttributes)
         {
             return GenerateHidden(
                 modelExplorer: null,
@@ -394,7 +392,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString Label(string expression, string labelText, object htmlAttributes)
+        public IHtmlContent Label(string expression, string labelText, object htmlAttributes)
         {
             var modelExplorer = ExpressionMetadataProvider.FromStringExpression(expression, ViewData, MetadataProvider);
             return GenerateLabel(
@@ -405,7 +403,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString ListBox(string expression, IEnumerable<SelectListItem> selectList, object htmlAttributes)
+        public IHtmlContent ListBox(string expression, IEnumerable<SelectListItem> selectList, object htmlAttributes)
         {
             return GenerateListBox(
                 modelExplorer: null,
@@ -439,7 +437,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return RenderPartialCoreAsync(partialViewName, model, viewData, ViewContext.Writer);
         }
 
-        protected virtual HtmlString GenerateDisplay(ModelExplorer modelExplorer,
+        protected virtual IHtmlContent GenerateDisplay(ModelExplorer modelExplorer,
                                                      string htmlFieldName,
                                                      string templateName,
                                                      object additionalViewData)
@@ -453,9 +451,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                                                       readOnly: true,
                                                       additionalViewData: additionalViewData);
 
-            var templateResult = templateBuilder.Build();
-
-            return new HtmlString(templateResult);
+            return templateBuilder.Build();
         }
 
         protected virtual async Task RenderPartialCoreAsync([NotNull] string partialViewName,
@@ -491,7 +487,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString Password(string expression, object value, object htmlAttributes)
+        public IHtmlContent Password(string expression, object value, object htmlAttributes)
         {
             return GeneratePassword(
                 modelExplorer: null,
@@ -501,7 +497,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString RadioButton(string expression, object value, bool? isChecked, object htmlAttributes)
+        public IHtmlContent RadioButton(string expression, object value, bool? isChecked, object htmlAttributes)
         {
             return GenerateRadioButton(
                 modelExplorer: null,
@@ -512,19 +508,19 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString Raw(string value)
+        public IHtmlContent Raw(string value)
         {
             return new HtmlString(value);
         }
 
         /// <inheritdoc />
-        public HtmlString Raw(object value)
+        public IHtmlContent Raw(object value)
         {
             return new HtmlString(value == null ? null : value.ToString());
         }
 
         /// <inheritdoc />
-        public HtmlString RouteLink(
+        public IHtmlContent RouteLink(
             [NotNull] string linkText,
             string routeName,
             string protocol,
@@ -546,17 +542,17 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.Normal);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
 
         /// <inheritdoc />
-        public HtmlString ValidationMessage(string expression, string message, object htmlAttributes, string tag)
+        public IHtmlContent ValidationMessage(string expression, string message, object htmlAttributes, string tag)
         {
             return GenerateValidationMessage(expression, message, htmlAttributes, tag);
         }
 
         /// <inheritdoc />
-        public HtmlString ValidationSummary(
+        public IHtmlContent ValidationSummary(
             bool excludePropertyErrors,
             string message,
             object htmlAttributes,
@@ -584,7 +580,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString TextArea(string expression, string value, int rows, int columns, object htmlAttributes)
+        public IHtmlContent TextArea(string expression, string value, int rows, int columns, object htmlAttributes)
         {
             var modelExplorer = ExpressionMetadataProvider.FromStringExpression(expression, ViewData, MetadataProvider);
             if (value != null)
@@ -606,7 +602,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString TextBox(string expression, object value, string format, object htmlAttributes)
+        public IHtmlContent TextBox(string expression, object value, string format, object htmlAttributes)
         {
             return GenerateTextBox(modelExplorer: null, expression: expression, value: value, format: format,
                 htmlAttributes: htmlAttributes);
@@ -628,7 +624,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return new MvcForm(ViewContext);
         }
 
-        protected virtual HtmlString GenerateCheckBox(
+        protected virtual IHtmlContent GenerateCheckBox(
             ModelExplorer modelExplorer,
             string expression,
             bool? isChecked,
@@ -647,9 +643,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            var elements = checkbox.ToString(TagRenderMode.SelfClosing) + hidden.ToString(TagRenderMode.SelfClosing);
+            var elements = new BufferedHtmlContent();
+            elements.Append(checkbox.ToHtmlContent(TagRenderMode.SelfClosing));
+            elements.Append(hidden.ToHtmlContent(TagRenderMode.SelfClosing));
 
-            return new HtmlString(elements);
+            return elements;
         }
 
         protected virtual string GenerateDisplayName([NotNull] ModelExplorer modelExplorer, string expression)
@@ -672,7 +670,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return modelExplorer.GetSimpleDisplayText() ?? string.Empty;
         }
 
-        protected HtmlString GenerateDropDown(
+        protected IHtmlContent GenerateDropDown(
             ModelExplorer modelExplorer,
             string expression,
             IEnumerable<SelectListItem> selectList,
@@ -692,10 +690,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.Normal);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
 
-        protected virtual HtmlString GenerateEditor(
+        protected virtual IHtmlContent GenerateEditor(
             ModelExplorer modelExplorer,
             string htmlFieldName,
             string templateName,
@@ -711,9 +709,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 readOnly: false,
                 additionalViewData: additionalViewData);
 
-            var templateResult = templateBuilder.Build();
-
-            return new HtmlString(templateResult);
+            return templateBuilder.Build();
         }
 
         /// <summary>
@@ -755,7 +751,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes);
             if (tagBuilder != null)
             {
-                ViewContext.Writer.Write(tagBuilder.ToString(TagRenderMode.StartTag));
+                tagBuilder.ToHtmlContent(TagRenderMode.StartTag).WriteTo(ViewContext.Writer, _htmlEncoder);
             }
 
             return CreateForm();
@@ -797,13 +793,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes);
             if (tagBuilder != null)
             {
-                ViewContext.Writer.Write(tagBuilder.ToString(TagRenderMode.StartTag));
+                tagBuilder.ToHtmlContent(TagRenderMode.StartTag).WriteTo(ViewContext.Writer, _htmlEncoder);
             }
 
             return CreateForm();
         }
 
-        protected virtual HtmlString GenerateHidden(
+        protected virtual IHtmlContent GenerateHidden(
             ModelExplorer modelExplorer,
             string expression,
             object value,
@@ -823,7 +819,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.SelfClosing);
+            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
         }
 
         protected virtual string GenerateId(string expression)
@@ -834,7 +830,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return id;
         }
 
-        protected virtual HtmlString GenerateLabel(
+        protected virtual IHtmlContent GenerateLabel(
             [NotNull] ModelExplorer modelExplorer,
             string expression,
             string labelText,
@@ -851,10 +847,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.Normal);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
 
-        protected HtmlString GenerateListBox(
+        protected IHtmlContent GenerateListBox(
             ModelExplorer modelExplorer,
             string expression,
             IEnumerable<SelectListItem> selectList,
@@ -873,7 +869,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.Normal);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
 
         protected virtual string GenerateName(string expression)
@@ -882,7 +878,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return fullName;
         }
 
-        protected virtual HtmlString GeneratePassword(
+        protected virtual IHtmlContent GeneratePassword(
             ModelExplorer modelExplorer,
             string expression,
             object value,
@@ -899,10 +895,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.SelfClosing);
+            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
         }
 
-        protected virtual HtmlString GenerateRadioButton(
+        protected virtual IHtmlContent GenerateRadioButton(
             ModelExplorer modelExplorer,
             string expression,
             object value,
@@ -921,10 +917,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.SelfClosing);
+            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
         }
 
-        protected virtual HtmlString GenerateTextArea(
+        protected virtual IHtmlContent GenerateTextArea(
             ModelExplorer modelExplorer,
             string expression,
             int rows,
@@ -943,10 +939,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.Normal);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
 
-        protected virtual HtmlString GenerateTextBox(
+        protected virtual IHtmlContent GenerateTextBox(
             ModelExplorer modelExplorer,
             string expression,
             object value,
@@ -965,10 +961,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.SelfClosing);
+            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
         }
 
-        protected virtual HtmlString GenerateValidationMessage(
+        protected virtual IHtmlContent GenerateValidationMessage(
             string expression,
             string message,
             object htmlAttributes,
@@ -985,10 +981,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.Normal);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
 
-        protected virtual HtmlString GenerateValidationSummary(
+        protected virtual IHtmlContent GenerateValidationSummary(
             bool excludePropertyErrors,
             string message,
             object htmlAttributes,
@@ -1005,7 +1001,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlString(TagRenderMode.Normal);
+            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
         }
 
         protected virtual string GenerateValue(string expression, object value, string format, bool useViewData)

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Html/HtmlHelperOfT.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering.Expressions;
 using Microsoft.AspNet.Mvc.ViewFeatures;
@@ -56,7 +57,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString CheckBoxFor(
+        public IHtmlContent CheckBoxFor(
             [NotNull] Expression<Func<TModel, bool>> expression,
             object htmlAttributes)
         {
@@ -66,7 +67,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString DropDownListFor<TResult>(
+        public IHtmlContent DropDownListFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             IEnumerable<SelectListItem> selectList,
             string optionLabel,
@@ -79,7 +80,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString DisplayFor<TResult>(
+        public IHtmlContent DisplayFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName,
             string htmlFieldName,
@@ -127,7 +128,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString EditorFor<TResult>(
+        public IHtmlContent EditorFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName,
             string htmlFieldName,
@@ -143,7 +144,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString HiddenFor<TResult>(
+        public IHtmlContent HiddenFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object htmlAttributes)
         {
@@ -163,7 +164,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString LabelFor<TResult>(
+        public IHtmlContent LabelFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string labelText,
             object htmlAttributes)
@@ -177,7 +178,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString ListBoxFor<TResult>(
+        public IHtmlContent ListBoxFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             IEnumerable<SelectListItem> selectList,
             object htmlAttributes)
@@ -196,7 +197,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString PasswordFor<TResult>(
+        public IHtmlContent PasswordFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object htmlAttributes)
         {
@@ -209,7 +210,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString RadioButtonFor<TResult>(
+        public IHtmlContent RadioButtonFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             [NotNull] object value,
             object htmlAttributes)
@@ -224,7 +225,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString TextAreaFor<TResult>(
+        public IHtmlContent TextAreaFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             int rows,
             int columns,
@@ -235,7 +236,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString TextBoxFor<TResult>(
+        public IHtmlContent TextBoxFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string format,
             object htmlAttributes)
@@ -267,7 +268,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         }
 
         /// <inheritdoc />
-        public HtmlString ValidationMessageFor<TResult>(
+        public IHtmlContent ValidationMessageFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string message,
             object htmlAttributes,

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Html/IHtmlGenerator.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.ModelBinding.Validation;
 using Microsoft.Framework.Internal;
@@ -35,8 +36,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// Genrate an <input type="hidden".../> element containing an antiforgery token.
         /// </summary>
         /// <param name="viewContext">The <see cref="ViewContext"/> instance for the current scope.</param>
-        /// <returns>An <see cref="HtmlString"/> instance for the &lt;input type="hidden".../&gt; element.</returns>
-        HtmlString GenerateAntiforgery([NotNull] ViewContext viewContext);
+        /// <returns>An <see cref="IHtmlContent"/> instance for the &lt;input type="hidden".../&gt; element.</returns>
+        IHtmlContent GenerateAntiforgery([NotNull] ViewContext viewContext);
 
         /// <summary>
         /// Generate a &lt;input type="checkbox".../&gt; element. 

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Html/TagBuilder.cs

@@ -6,23 +6,15 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 using System.Text;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Mvc.ViewFeatures;
 using Microsoft.Framework.Internal;
-using Microsoft.Framework.WebEncoders;
 
 namespace Microsoft.AspNet.Mvc.Rendering
 {
     public class TagBuilder
     {
-        private string _innerHtml;
-        private readonly IHtmlEncoder _htmlEncoder;
-
         public TagBuilder(string tagName)
-            : this(tagName, HtmlEncoder.Default)
-        {
-        }
-
-        public TagBuilder(string tagName, [NotNull] IHtmlEncoder htmlEncoder)
         {
             if (string.IsNullOrEmpty(tagName))
             {
@@ -31,16 +23,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
             TagName = tagName;
             Attributes = new SortedDictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-            _htmlEncoder = htmlEncoder;
         }
 
         public IDictionary<string, string> Attributes { get; private set; }
 
-        public string InnerHtml
-        {
-            get { return _innerHtml ?? string.Empty; }
-            set { _innerHtml = value; }
-        }
+        public IHtmlContent InnerHtml { get; [param: NotNull] set; } = HtmlString.Empty;
 
         public string TagName { get; private set; }
 
@@ -138,7 +125,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
         }
 
-        private void AppendAttributes(TextWriter textWriter)
+        private void AppendAttributes(BufferedHtmlContent content)
         {
             foreach (var attribute in Attributes)
             {
@@ -149,11 +136,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     continue;
                 }
 
-                textWriter.Write(' ');
-                textWriter.Write(key);
-                textWriter.Write("=\"");
-                _htmlEncoder.HtmlEncode(attribute.Value, textWriter);
-                textWriter.Write('"');
+                content.Append(" ");
+                content.Append(key);
+                content.Append("=\"");
+                content.Append(new StringHtmlContent(attribute.Value));
+                content.Append("\"");
             }
         }
 
@@ -195,56 +182,51 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
         public void SetInnerText(string innerText)
         {
-            InnerHtml = _htmlEncoder.HtmlEncode(innerText);
+            InnerHtml = new StringHtmlContent(innerText);
         }
 
-        public HtmlString ToHtmlString(TagRenderMode renderMode)
+        /// <summary>
+        /// Converts the <see cref="TagBuilder"/> to <see cref="IHtmlContent"/> with the specified
+        /// <see cref="TagRenderMode"/>.
+        /// </summary>
+        /// <param name="renderMode"><see cref="TagRenderMode"/> with which the <see cref="TagBuilder"/>
+        /// should be written.</param>
+        /// <returns><see cref="IHtmlContent"/> containing the contents of the <see cref="TagBuilder"/>.</returns>
+        public IHtmlContent ToHtmlContent(TagRenderMode renderMode)
         {
-            return new HtmlString(ToString(renderMode));
-        }
-
-        public override string ToString()
-        {
-            return ToString(TagRenderMode.Normal);
-        }
-
-        public string ToString(TagRenderMode renderMode)
-        {
-            using (var stringWriter = new StringWriter())
+            var content = new BufferedHtmlContent();
+            switch (renderMode)
             {
-                switch (renderMode)
-                {
-                    case TagRenderMode.StartTag:
-                        stringWriter.Write('<');
-                        stringWriter.Write(TagName);
-                        AppendAttributes(stringWriter);
-                        stringWriter.Write('>');
-                        break;
-                    case TagRenderMode.EndTag:
-                        stringWriter.Write("</");
-                        stringWriter.Write(TagName);
-                        stringWriter.Write('>');
-                        break;
-                    case TagRenderMode.SelfClosing:
-                        stringWriter.Write('<');
-                        stringWriter.Write(TagName);
-                        AppendAttributes(stringWriter);
-                        stringWriter.Write(" />");
-                        break;
-                    default:
-                        stringWriter.Write('<');
-                        stringWriter.Write(TagName);
-                        AppendAttributes(stringWriter);
-                        stringWriter.Write('>');
-                        stringWriter.Write(InnerHtml);
-                        stringWriter.Write("</");
-                        stringWriter.Write(TagName);
-                        stringWriter.Write('>');
-                        break;
-                }
-
-                return stringWriter.ToString();
+                case TagRenderMode.StartTag:
+                    content.Append("<");
+                    content.Append(TagName);
+                    AppendAttributes(content);
+                    content.Append(">");
+                    break;
+                case TagRenderMode.EndTag:
+                    content.Append("</");
+                    content.Append(TagName);
+                    content.Append(">");
+                    break;
+                case TagRenderMode.SelfClosing:
+                    content.Append("<");
+                    content.Append(TagName);
+                    AppendAttributes(content);
+                    content.Append(" />");
+                    break;
+                default:
+                    content.Append("<");
+                    content.Append(TagName);
+                    AppendAttributes(content);
+                    content.Append(">");
+                    content.Append(InnerHtml);
+                    content.Append("</");
+                    content.Append(TagName);
+                    content.Append(">");
+                    break;
             }
+
+            return content;
         }
 
         private static class Html401IdUtil

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/HtmlHelperDisplayExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Linq.Expressions;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -21,7 +22,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// Expression name, relative to the current model. May identify a single property or an
         /// <see cref="object"/> that contains the properties to display.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -36,7 +37,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Display([NotNull] this IHtmlHelper htmlHelper, string expression)
+        public static IHtmlContent Display([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.Display(expression, templateName: null, htmlFieldName: null, additionalViewData: null);
         }
@@ -56,7 +57,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -71,7 +72,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Display(
+        public static IHtmlContent Display(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object additionalViewData)
@@ -94,7 +95,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="object"/> that contains the properties to display.
         /// </param>
         /// <param name="templateName">The name of the template used to create the HTML markup.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -109,7 +110,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Display(
+        public static IHtmlContent Display(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string templateName)
@@ -133,7 +134,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -148,7 +149,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Display(
+        public static IHtmlContent Display(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string templateName,
@@ -176,7 +177,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// A <see cref="string"/> used to disambiguate the names of HTML elements that are created for
         /// properties that have the same name.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -191,7 +192,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Display(
+        public static IHtmlContent Display(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string templateName,
@@ -208,7 +209,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="expression">An expression to be evaluated against the current model.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -219,7 +220,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayFor<TModel, TResult>(
+        public static IHtmlContent DisplayFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression)
         {
@@ -244,7 +245,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -255,7 +256,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayFor<TModel, TResult>(
+        public static IHtmlContent DisplayFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object additionalViewData)
@@ -277,7 +278,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="templateName">The name of the template used to create the HTML markup.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -288,7 +289,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayFor<TModel, TResult>(
+        public static IHtmlContent DisplayFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName)
@@ -315,7 +316,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -326,7 +327,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayFor<TModel, TResult>(
+        public static IHtmlContent DisplayFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName,
@@ -353,7 +354,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -364,7 +365,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayFor<TModel, TResult>(
+        public static IHtmlContent DisplayFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName,
@@ -382,7 +383,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// model's <see cref="ModelBinding.ModelMetadata"/>.
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -393,7 +394,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayForModel([NotNull] this IHtmlHelper htmlHelper)
+        public static IHtmlContent DisplayForModel([NotNull] this IHtmlHelper htmlHelper)
         {
             return htmlHelper.Display(
                 expression: null,
@@ -412,7 +413,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -423,7 +424,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayForModel([NotNull] this IHtmlHelper htmlHelper, object additionalViewData)
+        public static IHtmlContent DisplayForModel([NotNull] this IHtmlHelper htmlHelper, object additionalViewData)
         {
             return htmlHelper.Display(
                 expression: null,
@@ -438,7 +439,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="templateName">The name of the template used to create the HTML markup.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -449,7 +450,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayForModel([NotNull] this IHtmlHelper htmlHelper, string templateName)
+        public static IHtmlContent DisplayForModel([NotNull] this IHtmlHelper htmlHelper, string templateName)
         {
             return htmlHelper.Display(
                 expression: null,
@@ -470,7 +471,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -481,7 +482,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayForModel(
+        public static IHtmlContent DisplayForModel(
             [NotNull] this IHtmlHelper htmlHelper,
             string templateName,
             object additionalViewData)
@@ -504,7 +505,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// A <see cref="string"/> used to disambiguate the names of HTML elements that are created for
         /// properties that have the same name.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -515,7 +516,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayForModel(
+        public static IHtmlContent DisplayForModel(
             [NotNull] this IHtmlHelper htmlHelper,
             string templateName,
             string htmlFieldName)
@@ -543,7 +544,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -554,7 +555,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString DisplayForModel(
+        public static IHtmlContent DisplayForModel(
             [NotNull] this IHtmlHelper htmlHelper,
             string templateName,
             string htmlFieldName,

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/HtmlHelperEditorExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Linq.Expressions;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -21,7 +22,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// Expression name, relative to the current model. May identify a single property or an
         /// <see cref="object"/> that contains the properties to edit.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -36,7 +37,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Editor([NotNull] this IHtmlHelper htmlHelper, string expression)
+        public static IHtmlContent Editor([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.Editor(expression, templateName: null, htmlFieldName: null, additionalViewData: null);
         }
@@ -56,7 +57,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -71,7 +72,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Editor(
+        public static IHtmlContent Editor(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object additionalViewData)
@@ -94,7 +95,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="object"/> that contains the properties to edit.
         /// </param>
         /// <param name="templateName">The name of the template used to create the HTML markup.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -109,7 +110,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Editor([NotNull] this IHtmlHelper htmlHelper, string expression, string templateName)
+        public static IHtmlContent Editor([NotNull] this IHtmlHelper htmlHelper, string expression, string templateName)
         {
             return htmlHelper.Editor(expression, templateName, htmlFieldName: null, additionalViewData: null);
         }
@@ -130,7 +131,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -145,7 +146,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Editor(
+        public static IHtmlContent Editor(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string templateName,
@@ -173,7 +174,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// A <see cref="string"/> used to disambiguate the names of HTML elements that are created for
         /// properties that have the same name.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -188,7 +189,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString Editor(
+        public static IHtmlContent Editor(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string templateName,
@@ -205,7 +206,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="expression">An expression to be evaluated against the current model.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -216,7 +217,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorFor<TModel, TResult>(
+        public static IHtmlContent EditorFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression)
         {
@@ -237,7 +238,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -248,7 +249,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorFor<TModel, TResult>(
+        public static IHtmlContent EditorFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object additionalViewData)
@@ -270,7 +271,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="templateName">The name of the template that is used to create the HTML markup.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -281,7 +282,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorFor<TModel, TResult>(
+        public static IHtmlContent EditorFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName)
@@ -304,7 +305,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -315,7 +316,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorFor<TModel, TResult>(
+        public static IHtmlContent EditorFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName,
@@ -342,7 +343,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -353,7 +354,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorFor<TModel, TResult>(
+        public static IHtmlContent EditorFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName,
@@ -367,7 +368,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// model's <see cref="ModelBinding.ModelMetadata"/>.
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -378,7 +379,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorForModel([NotNull] this IHtmlHelper htmlHelper)
+        public static IHtmlContent EditorForModel([NotNull] this IHtmlHelper htmlHelper)
         {
             return htmlHelper.Editor(
                 expression: null,
@@ -397,7 +398,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -408,7 +409,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorForModel([NotNull] this IHtmlHelper htmlHelper, object additionalViewData)
+        public static IHtmlContent EditorForModel([NotNull] this IHtmlHelper htmlHelper, object additionalViewData)
         {
             return htmlHelper.Editor(
                 expression: null,
@@ -423,7 +424,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="templateName">The name of the template used to create the HTML markup.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -434,7 +435,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorForModel([NotNull] this IHtmlHelper htmlHelper, string templateName)
+        public static IHtmlContent EditorForModel([NotNull] this IHtmlHelper htmlHelper, string templateName)
         {
             return htmlHelper.Editor(
                 expression: null,
@@ -455,7 +456,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -466,7 +467,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorForModel(
+        public static IHtmlContent EditorForModel(
             [NotNull] this IHtmlHelper htmlHelper,
             string templateName,
             object additionalViewData)
@@ -489,7 +490,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// A <see cref="string"/> used to disambiguate the names of HTML elements that are created for
         /// properties that have the same name.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -500,7 +501,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorForModel(
+        public static IHtmlContent EditorForModel(
             [NotNull] this IHtmlHelper htmlHelper,
             string templateName,
             string htmlFieldName)
@@ -528,7 +529,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// that can contain additional view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/>
         /// instance created for the template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -539,7 +540,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// case-sensitive file systems.
         /// </para>
         /// </remarks>
-        public static HtmlString EditorForModel(
+        public static IHtmlContent EditorForModel(
             [NotNull] this IHtmlHelper htmlHelper,
             string templateName,
             string htmlFieldName,

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/HtmlHelperInputExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Linq.Expressions;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -18,7 +19,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; elements.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; elements.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set checkbox
@@ -48,7 +49,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// value "checked" if the <see cref="bool"/> values is <c>true</c>; does not include the attribute otherwise.
         /// </para>
         /// </remarks>
-        public static HtmlString CheckBox([NotNull] this IHtmlHelper htmlHelper, string expression)
+        public static IHtmlContent CheckBox([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.CheckBox(expression, isChecked: null, htmlAttributes: null);
         }
@@ -60,7 +61,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
         /// <param name="isChecked">If <c>true</c>, checkbox is initially checked.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; elements.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; elements.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set checkbox
@@ -91,7 +92,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// value "checked" if the <see cref="bool"/> values is <c>true</c>; does not include the attribute otherwise.
         /// </para>
         /// </remarks>
-        public static HtmlString CheckBox(
+        public static IHtmlContent CheckBox(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             bool isChecked)
@@ -110,7 +111,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; elements.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; elements.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set checkbox
@@ -141,7 +142,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// value "checked" if the <see cref="bool"/> values is <c>true</c>; does not include the attribute otherwise.
         /// </para>
         /// </remarks>
-        public static HtmlString CheckBox(
+        public static IHtmlContent CheckBox(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object htmlAttributes)
@@ -155,7 +156,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper{TModel}"/> instance this method extends.</param>
         /// <param name="expression">An expression to be evaluated against the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; elements.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; elements.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -179,7 +180,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// value "checked" if the <see cref="bool"/> values is <c>true</c>; does not include the attribute otherwise.
         /// </para>
         /// </remarks>
-        public static HtmlString CheckBoxFor<TModel>(
+        public static IHtmlContent CheckBoxFor<TModel>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, bool>> expression)
         {
@@ -191,7 +192,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -217,7 +218,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString Hidden([NotNull] this IHtmlHelper htmlHelper, string expression)
+        public static IHtmlContent Hidden([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.Hidden(expression, value: null, htmlAttributes: null);
         }
@@ -228,7 +229,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
         /// <param name="value">If non-<c>null</c>, value to include in the element.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -255,7 +256,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString Hidden(
+        public static IHtmlContent Hidden(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object value)
@@ -270,7 +271,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="expression">An expression to be evaluated against the current model.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -290,7 +291,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString HiddenFor<TModel, TResult>(
+        public static IHtmlContent HiddenFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression)
         {
@@ -302,13 +303,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;input&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute. Sets &lt;input&gt; element's "value" attribute to <c>string.Empty</c>.
         /// </remarks>
-        public static HtmlString Password([NotNull] this IHtmlHelper htmlHelper, string expression)
+        public static IHtmlContent Password([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.Password(expression, value: null, htmlAttributes: null);
         }
@@ -319,7 +320,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
         /// <param name="value">If non-<c>null</c>, value to include in the element.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -332,7 +333,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString Password(
+        public static IHtmlContent Password(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object value)
@@ -347,7 +348,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="expression">An expression to be evaluated against the current model.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -363,7 +364,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString PasswordFor<TModel, TResult>(
+        public static IHtmlContent PasswordFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression)
         {
@@ -376,7 +377,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
         /// <param name="value">Value to include in the element. Must not be <c>null</c>.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -408,7 +409,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// the attribute otherwise.
         /// </para>
         /// </remarks>
-        public static HtmlString RadioButton(
+        public static IHtmlContent RadioButton(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object value)
@@ -430,7 +431,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -469,7 +470,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// the attribute otherwise.
         /// </para>
         /// </remarks>
-        public static HtmlString RadioButton(
+        public static IHtmlContent RadioButton(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object value,
@@ -491,7 +492,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// If <c>true</c>, radio button is initially selected. Must not be <c>null</c> if
         /// <paramref name="value"/> is also <c>null</c>.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -529,7 +530,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// the attribute otherwise.
         /// </para>
         /// </remarks>
-        public static HtmlString RadioButton(
+        public static IHtmlContent RadioButton(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object value,
@@ -546,7 +547,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="value">Value to include in the element. Must not be <c>null</c>.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -571,7 +572,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <paramref name="value"/>; does not include the attribute otherwise.
         /// </para>
         /// </remarks>
-        public static HtmlString RadioButtonFor<TModel, TResult>(
+        public static IHtmlContent RadioButtonFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             [NotNull] object value)
@@ -584,7 +585,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -610,7 +611,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextBox([NotNull] this IHtmlHelper htmlHelper, string expression)
+        public static IHtmlContent TextBox([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.TextBox(expression, value: null, format: null, htmlAttributes: null);
         }
@@ -621,7 +622,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
         /// <param name="value">If non-<c>null</c>, value to include in the element.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -650,7 +651,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextBox(
+        public static IHtmlContent TextBox(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object value)
@@ -667,7 +668,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="format">
         /// The composite format <see cref="string"/> (see http://msdn.microsoft.com/en-us/library/txafckwd.aspx).
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -701,7 +702,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextBox(
+        public static IHtmlContent TextBox(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object value,
@@ -721,7 +722,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -751,7 +752,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextBox(
+        public static IHtmlContent TextBox(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object value,
@@ -767,7 +768,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="expression">An expression to be evaluated against the current model.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -786,7 +787,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextBoxFor<TModel, TResult>(
+        public static IHtmlContent TextBoxFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression)
         {
@@ -803,7 +804,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -824,7 +825,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextBoxFor<TModel, TResult>(
+        public static IHtmlContent TextBoxFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string format)
@@ -844,7 +845,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -864,7 +865,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextBoxFor<TModel, TResult>(
+        public static IHtmlContent TextBoxFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object htmlAttributes)
@@ -877,7 +878,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;textarea&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;textarea&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -903,7 +904,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextArea(
+        public static IHtmlContent TextArea(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression)
         {
@@ -920,7 +921,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;textarea&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;textarea&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -946,7 +947,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextArea(
+        public static IHtmlContent TextArea(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object htmlAttributes)
@@ -960,7 +961,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
         /// <param name="value">If non-<c>null</c>, value to include in the element.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;textarea&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;textarea&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -987,7 +988,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextArea(
+        public static IHtmlContent TextArea(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string value)
@@ -1006,7 +1007,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;textarea&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;textarea&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -1033,7 +1034,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextArea(
+        public static IHtmlContent TextArea(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string value,
@@ -1049,7 +1050,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="expression">An expression to be evaluated against the current model.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;textarea&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;textarea&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -1068,7 +1069,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextAreaFor<TModel, TResult>(
+        public static IHtmlContent TextAreaFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression)
         {
@@ -1087,7 +1088,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;textarea&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;textarea&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -1106,7 +1107,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        public static HtmlString TextAreaFor<TModel, TResult>(
+        public static IHtmlContent TextAreaFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object htmlAttributes)

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/HtmlHelperLabelExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Linq.Expressions;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -17,8 +18,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString Label([NotNull] this IHtmlHelper htmlHelper, string expression)
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent Label([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.Label(expression, labelText: null, htmlAttributes: null);
         }
@@ -29,8 +30,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
         /// <param name="labelText">The inner text of the element.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString Label([NotNull] this IHtmlHelper htmlHelper, string expression, string labelText)
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent Label([NotNull] this IHtmlHelper htmlHelper, string expression, string labelText)
         {
             return htmlHelper.Label(expression, labelText, htmlAttributes: null);
         }
@@ -42,8 +43,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="expression">An expression to be evaluated against the current model.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString LabelFor<TModel, TResult>(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent LabelFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression)
         {
@@ -58,8 +59,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="labelText">The inner text of the element.</param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString LabelFor<TModel, TResult>(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent LabelFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string labelText)
@@ -79,8 +80,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString LabelFor<TModel, TResult>(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent LabelFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object htmlAttributes)
@@ -92,8 +93,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// Returns a &lt;label&gt; element for the current model.
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString LabelForModel([NotNull] this IHtmlHelper htmlHelper)
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent LabelForModel([NotNull] this IHtmlHelper htmlHelper)
         {
             return htmlHelper.Label(expression: null, labelText: null, htmlAttributes: null);
         }
@@ -103,8 +104,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="labelText">The inner text of the element.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString LabelForModel([NotNull] this IHtmlHelper htmlHelper, string labelText)
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent LabelForModel([NotNull] this IHtmlHelper htmlHelper, string labelText)
         {
             return htmlHelper.Label(expression: null, labelText: labelText, htmlAttributes: null);
         }
@@ -118,8 +119,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString LabelForModel([NotNull] this IHtmlHelper htmlHelper, object htmlAttributes)
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent LabelForModel([NotNull] this IHtmlHelper htmlHelper, object htmlAttributes)
         {
             return htmlHelper.Label(expression: null, labelText: null, htmlAttributes: htmlAttributes);
         }
@@ -134,8 +135,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        public static HtmlString LabelForModel(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        public static IHtmlContent LabelForModel(
             [NotNull] this IHtmlHelper htmlHelper,
             string labelText,
             object htmlAttributes)

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/HtmlHelperLinkExtensions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -16,8 +17,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="helper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="linkText">The inner text of the anchor element. Must not be <c>null</c>.</param>
         /// <param name="actionName">The name of the action.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString ActionLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent ActionLink(
             [NotNull] this IHtmlHelper helper,
             [NotNull] string linkText,
             string actionName)
@@ -46,8 +47,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the route
         /// parameters.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString ActionLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent ActionLink(
             [NotNull] this IHtmlHelper helper,
             [NotNull] string linkText,
             string actionName,
@@ -82,8 +83,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString ActionLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent ActionLink(
             [NotNull] this IHtmlHelper helper,
             [NotNull] string linkText,
             string actionName,
@@ -108,8 +109,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="linkText">The inner text of the anchor element. Must not be <c>null</c>.</param>
         /// <param name="actionName">The name of the action.</param>
         /// <param name="controllerName">The name of the controller.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString ActionLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent ActionLink(
             [NotNull] this IHtmlHelper helper,
             [NotNull] string linkText,
             string actionName,
@@ -140,8 +141,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the route
         /// parameters.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString ActionLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent ActionLink(
             [NotNull] this IHtmlHelper helper,
             [NotNull] string linkText,
             string actionName,
@@ -178,8 +179,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString ActionLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent ActionLink(
             [NotNull] this IHtmlHelper helper,
             [NotNull] string linkText,
             string actionName,
@@ -210,8 +211,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the route
         /// parameters.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString RouteLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent RouteLink(
             [NotNull] this IHtmlHelper htmlHelper,
             [NotNull] string linkText,
             object routeValues)
@@ -232,8 +233,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="linkText">The inner text of the anchor element. Must not be <c>null</c>.</param>
         /// <param name="routeName">The name of the route.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString RouteLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent RouteLink(
             [NotNull] this IHtmlHelper htmlHelper,
             [NotNull] string linkText,
             string routeName)
@@ -261,8 +262,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the route
         /// parameters.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString RouteLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent RouteLink(
             [NotNull] this IHtmlHelper htmlHelper,
             [NotNull] string linkText,
             string routeName,
@@ -295,8 +296,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString RouteLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent RouteLink(
             [NotNull] this IHtmlHelper htmlHelper,
             [NotNull] string linkText,
             object routeValues,
@@ -330,8 +331,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing the HTML
         /// attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        public static HtmlString RouteLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        public static IHtmlContent RouteLink(
             [NotNull] this IHtmlHelper htmlHelper,
             [NotNull] string linkText,
             string routeName,

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/HtmlHelperSelectExtensions.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -18,13 +19,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        public static HtmlString DropDownList([NotNull] this IHtmlHelper htmlHelper, string expression)
+        public static IHtmlContent DropDownList([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.DropDownList(expression, selectList: null, optionLabel: null, htmlAttributes: null);
         }
@@ -38,13 +39,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="optionLabel">
         /// The text for a default empty item. Does not include such an item if argument is <c>null</c>.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        public static HtmlString DropDownList(
+        public static IHtmlContent DropDownList(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string optionLabel)
@@ -66,13 +67,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// A collection of <see cref="SelectListItem"/> objects used to populate the &lt;select&gt; element with
         /// &lt;optgroup&gt; and &lt;option&gt; elements.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        public static HtmlString DropDownList(
+        public static IHtmlContent DropDownList(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             IEnumerable<SelectListItem> selectList)
@@ -94,13 +95,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the &lt;select&gt; element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        public static HtmlString DropDownList(
+        public static IHtmlContent DropDownList(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             IEnumerable<SelectListItem> selectList,
@@ -122,13 +123,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="optionLabel">
         /// The text for a default empty item. Does not include such an item if argument is <c>null</c>.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        public static HtmlString DropDownList(
+        public static IHtmlContent DropDownList(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             IEnumerable<SelectListItem> selectList,
@@ -149,13 +150,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
         /// <paramref name="expression"/> to set &lt;select&gt; element's "name" attribute. Sanitizes the string
         /// representation of the <paramref name="expression"/> to set element's "id" attribute.
         /// </remarks>
-        public static HtmlString DropDownListFor<TModel, TResult>(
+        public static IHtmlContent DropDownListFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             IEnumerable<SelectListItem> selectList)
@@ -179,13 +180,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
         /// <paramref name="expression"/> to set &lt;select&gt; element's "name" attribute. Sanitizes the string
         /// representation of the <paramref name="expression"/> to set element's "id" attribute.
         /// </remarks>
-        public static HtmlString DropDownListFor<TModel, TResult>(
+        public static IHtmlContent DropDownListFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             IEnumerable<SelectListItem> selectList,
@@ -213,13 +214,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
         /// <paramref name="expression"/> to set &lt;select&gt; element's "name" attribute. Sanitizes the string
         /// representation of the <paramref name="expression"/> to set element's "id" attribute.
         /// </remarks>
-        public static HtmlString DropDownListFor<TModel, TResult>(
+        public static IHtmlContent DropDownListFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             IEnumerable<SelectListItem> selectList,
@@ -233,13 +234,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        public static HtmlString ListBox([NotNull] this IHtmlHelper htmlHelper, string expression)
+        public static IHtmlContent ListBox([NotNull] this IHtmlHelper htmlHelper, string expression)
         {
             return htmlHelper.ListBox(expression, selectList: null, htmlAttributes: null);
         }
@@ -254,13 +255,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// A collection of <see cref="SelectListItem"/> objects used to populate the &lt;select&gt; element with
         /// &lt;optgroup&gt; and &lt;option&gt; elements.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        public static HtmlString ListBox(
+        public static IHtmlContent ListBox(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             IEnumerable<SelectListItem> selectList)
@@ -280,13 +281,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
         /// <paramref name="expression"/> to set &lt;select&gt; element's "name" attribute. Sanitizes the string
         /// representation of the <paramref name="expression"/> to set element's "id" attribute.
         /// </remarks>
-        public static HtmlString ListBoxFor<TModel, TResult>(
+        public static IHtmlContent ListBoxFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             IEnumerable<SelectListItem> selectList)

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/HtmlHelperValidationExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Linq.Expressions;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -19,14 +20,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="expression">Expression name, relative to the current model.</param>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
+        /// A new <see cref="IHtmlContent"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
         /// <c>null</c> if the <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
         /// <remarks>
         /// Method extracts an error string from the <see cref="ModelBinding.ModelStateDictionary"/> object. Message
         /// will always be visible but client-side validation may update the associated CSS class.
         /// </remarks>
-        public static HtmlString ValidationMessage(
+        public static IHtmlContent ValidationMessage(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression)
         {
@@ -45,10 +46,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// validation may update the associated CSS class.
         /// </param>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
+        /// A new <see cref="IHtmlContent"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
         /// <c>null</c> if the <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
-        public static HtmlString ValidationMessage(
+        public static IHtmlContent ValidationMessage(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string message)
@@ -69,14 +70,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// attributes.
         /// </param>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
+        /// A new <see cref="IHtmlContent"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
         /// <c>null</c> if the <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
         /// <remarks>
         /// Method extracts an error string from the <see cref="ModelBinding.ModelStateDictionary"/> object. Message
         /// will always be visible but client-side validation may update the associated CSS class.
         /// </remarks>
-        public static HtmlString ValidationMessage(
+        public static IHtmlContent ValidationMessage(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             object htmlAttributes)
@@ -100,10 +101,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="ViewContext.ValidationMessageElement"/>.
         /// </param>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <paramref name="tag"/> element. <c>null</c> if the
+        /// A new <see cref="IHtmlContent"/> containing a <paramref name="tag"/> element. <c>null</c> if the
         /// <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
-        public static HtmlString ValidationMessage(
+        public static IHtmlContent ValidationMessage(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string message,
@@ -130,10 +131,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// attributes.
         /// </param>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
+        /// A new <see cref="IHtmlContent"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
         /// <c>null</c> if the <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
-        public static HtmlString ValidationMessage(
+        public static IHtmlContent ValidationMessage(
             [NotNull] this IHtmlHelper htmlHelper,
             string expression,
             string message,
@@ -151,14 +152,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
+        /// A new <see cref="IHtmlContent"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
         /// <c>null</c> if the <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
         /// <remarks>
         /// Method extracts an error string from the <see cref="ModelBinding.ModelStateDictionary"/> object. Message
         /// will always be visible but client-side validation may update the associated CSS class.
         /// </remarks>
-        public static HtmlString ValidationMessageFor<TModel, TResult>(
+        public static IHtmlContent ValidationMessageFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression)
         {
@@ -179,10 +180,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
+        /// A new <see cref="IHtmlContent"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
         /// <c>null</c> if the <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
-        public static HtmlString ValidationMessageFor<TModel, TResult>(
+        public static IHtmlContent ValidationMessageFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string message)
@@ -210,10 +211,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
+        /// A new <see cref="IHtmlContent"/> containing a <see cref="ViewContext.ValidationMessageElement"/> element.
         /// <c>null</c> if the <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
-        public static HtmlString ValidationMessageFor<TModel, TResult>(
+        public static IHtmlContent ValidationMessageFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string message,
@@ -240,10 +241,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <typeparam name="TModel">The type of the model.</typeparam>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing the <paramref name="tag"/> element. <c>null</c> if the
+        /// A new <see cref="IHtmlContent"/> containing the <paramref name="tag"/> element. <c>null</c> if the
         /// <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
-        public static HtmlString ValidationMessageFor<TModel, TResult>(
+        public static IHtmlContent ValidationMessageFor<TModel, TResult>(
             [NotNull] this IHtmlHelper<TModel> htmlHelper,
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string message,
@@ -258,10 +259,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the &lt;ul&gt; element.
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the &lt;ul&gt; element.
         /// <see cref="HtmlString.Empty"/> if the current model is valid and client-side validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary([NotNull] this IHtmlHelper htmlHelper)
+        public static IHtmlContent ValidationSummary([NotNull] this IHtmlHelper htmlHelper)
         {
             return htmlHelper.ValidationSummary(
                 excludePropertyErrors: false,
@@ -279,10 +280,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// If <c>true</c>, display model-level errors only; otherwise display all errors.
         /// </param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the &lt;ul&gt; element.
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the &lt;ul&gt; element.
         /// <see cref="HtmlString.Empty"/> if the current model is valid and client-side validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary([NotNull] this IHtmlHelper htmlHelper, bool excludePropertyErrors)
+        public static IHtmlContent ValidationSummary([NotNull] this IHtmlHelper htmlHelper, bool excludePropertyErrors)
         {
             return htmlHelper.ValidationSummary(
                 excludePropertyErrors,
@@ -298,12 +299,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <param name="htmlHelper">The <see cref="IHtmlHelper"/> instance this method extends.</param>
         /// <param name="message">The message to display with the validation summary.</param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the
         /// <see cref="ViewContext.ValidationSummaryMessageElement" /> element (which wraps the
         /// <paramref name="message"/>) and the &lt;ul&gt; element. <see cref="HtmlString.Empty"/> if the current model
         /// is valid and client-side validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary([NotNull] this IHtmlHelper htmlHelper, string message)
+        public static IHtmlContent ValidationSummary([NotNull] this IHtmlHelper htmlHelper, string message)
         {
             return htmlHelper.ValidationSummary(
                 excludePropertyErrors: false,
@@ -323,11 +324,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="ViewContext.ValidationSummaryMessageElement" />.
         /// </param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the <paramref name="tag"/> element
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the <paramref name="tag"/> element
         /// and the &lt;ul&gt; element. <see cref="HtmlString.Empty"/> if the current model is valid and client-side
         /// validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary([NotNull] this IHtmlHelper htmlHelper, string message, string tag)
+        public static IHtmlContent ValidationSummary([NotNull] this IHtmlHelper htmlHelper, string message, string tag)
         {
             return htmlHelper.ValidationSummary(
                 excludePropertyErrors: false,
@@ -346,12 +347,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <param name="message">The message to display with the validation summary.</param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the
         /// <see cref="ViewContext.ValidationSummaryMessageElement" /> element (which, in turn, wraps the
         /// <paramref name="message"/>) and the &lt;ul&gt; element. <see cref="HtmlString.Empty"/> if the current model
         /// is valid and client-side validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary(
+        public static IHtmlContent ValidationSummary(
             [NotNull] this IHtmlHelper htmlHelper,
             bool excludePropertyErrors,
             string message)
@@ -375,12 +376,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// the HTML attributes.
         /// </param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the
         /// <see cref="ViewContext.ValidationSummaryMessageElement" /> element (which wraps the
         /// <paramref name="message"/>) and the &lt;ul&gt; element. <see cref="HtmlString.Empty"/> if the current model
         /// is valid and client-side validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary(
+        public static IHtmlContent ValidationSummary(
             [NotNull] this IHtmlHelper htmlHelper,
             string message,
             object htmlAttributes)
@@ -408,11 +409,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="ViewContext.ValidationSummaryMessageElement" />.
         /// </param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the <paramref name="tag"/> element
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the <paramref name="tag"/> element
         /// and the &lt;ul&gt; element. <see cref="HtmlString.Empty"/> if the current model is valid and client-side
         /// validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary(
+        public static IHtmlContent ValidationSummary(
             [NotNull] this IHtmlHelper htmlHelper,
             string message,
             object htmlAttributes,
@@ -439,11 +440,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="ViewContext.ValidationSummaryMessageElement" />.
         /// </param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the <paramref name="tag"/> element
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the <paramref name="tag"/> element
         /// and the &lt;ul&gt; element. <see cref="HtmlString.Empty"/> if the current model is valid and client-side
         /// validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary(
+        public static IHtmlContent ValidationSummary(
             [NotNull] this IHtmlHelper htmlHelper,
             bool excludePropertyErrors,
             string message,
@@ -471,12 +472,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// the HTML attributes.
         /// </param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the
         /// <see cref="ViewContext.ValidationSummaryMessageElement" /> element (which wraps the
         /// <paramref name="message"/>) and the &lt;ul&gt; element. <see cref="HtmlString.Empty"/> if the current model
         /// is valid and client-side validation is disabled).
         /// </returns>
-        public static HtmlString ValidationSummary(
+        public static IHtmlContent ValidationSummary(
             [NotNull] this IHtmlHelper htmlHelper,
             bool excludePropertyErrors,
             string message,

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/HtmlString.cs

@@ -3,6 +3,7 @@
 
 using System.IO;
 using Microsoft.AspNet.Html.Abstractions;
+using Microsoft.Framework.Internal;
 using Microsoft.Framework.WebEncoders;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -12,36 +13,24 @@ namespace Microsoft.AspNet.Mvc.Rendering
     /// </summary>
     public class HtmlString : IHtmlContent
     {
-        private static readonly HtmlString _empty = new HtmlString(string.Empty);
         private readonly string _input;
 
         /// <summary>
-        /// Instantiates a new instance of <see cref="HtmlString"/>.
+        /// Returns an <see cref="HtmlString"/> with empty content.
         /// </summary>
-        /// <param name="input"><c>string</c>to initialize <see cref="HtmlString"/>.</param>
+        public static readonly HtmlString Empty = new HtmlString(string.Empty);
+
+        /// <summary>
+        /// Creates a new instance of <see cref="HtmlString"/>.
+        /// </summary>
+        /// <param name="input"><c>string</c> to initialize <see cref="HtmlString"/>.</param>
         public HtmlString(string input)
         {
             _input = input;
         }
 
-        /// <summary>
-        /// Returns an <see cref="HtmlString"/> with empty content.
-        /// </summary>
-        public static HtmlString Empty
-        {
-            get
-            {
-                return _empty;
-            }
-        }
-
-        /// <summary>
-        /// Writes the value in this instance of <see cref="HtmlString"/> to the target
-        /// <paramref name="writer"/>.
-        /// </summary>
-        /// <param name="writer">The <see cref="TextWriter"/> to write contents to.</param>
-        /// <param name="encoder">The <see cref="IHtmlEncoder"/> with which the output must be encoded.</param>
-        public void WriteTo(TextWriter writer, IHtmlEncoder encoder)
+        /// <inheritdoc />
+        public void WriteTo([NotNull] TextWriter writer, [NotNull] IHtmlEncoder encoder)
         {
             writer.Write(_input);
         }

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/IHtmlHelper.cs

@@ -54,11 +54,6 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </summary>
         ITempDataDictionary TempData { get; }
 
-        /// <summary>
-        /// Gets the <see cref="IHtmlEncoder"/> to be used for encoding HTML.
-        /// </summary>
-        IHtmlEncoder HtmlEncoder { get; }
-
         /// <summary>
         /// Gets the <see cref="IUrlEncoder"/> to be used for encoding a URL.
         /// </summary>
@@ -88,8 +83,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        HtmlString ActionLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        IHtmlContent ActionLink(
             [NotNull] string linkText,
             string actionName,
             string controllerName,
@@ -103,8 +98,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// Returns a &lt;hidden&gt; element (antiforgery token) that will be validated when the containing
         /// &lt;form&gt; is submitted.
         /// </summary>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;hidden&gt; element.</returns>
-        HtmlString AntiForgeryToken();
+        /// <returns><see cref="IHtmlContent"/> containing the &lt;hidden&gt; element.</returns>
+        IHtmlContent AntiForgeryToken();
 
         /// <summary>
         /// Renders a &lt;form&gt; start tag to the response. When the user submits the form, the action with name
@@ -174,7 +169,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the checkbox element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; elements.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; elements.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set checkbox
@@ -206,7 +201,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// value "checked" if the <see cref="bool"/> values is <c>true</c>; does not include the attribute otherwise.
         /// </para>
         /// </remarks>
-        HtmlString CheckBox(string expression, bool? isChecked, object htmlAttributes);
+        IHtmlContent CheckBox(string expression, bool? isChecked, object htmlAttributes);
 
         /// <summary>
         /// Returns HTML markup for the <paramref name="expression"/>, using a display template, specified HTML field
@@ -227,7 +222,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/> instance created for the
         /// template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
@@ -238,7 +233,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <c>"prop"</c> which identifies the current model's "prop" property.
         /// </para>
         /// </remarks>
-        HtmlString Display(
+        IHtmlContent Display(
             string expression,
             string templateName,
             string htmlFieldName,
@@ -277,13 +272,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the &lt;select&gt; element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        HtmlString DropDownList(
+        IHtmlContent DropDownList(
             string expression,
             IEnumerable<SelectListItem> selectList,
             string optionLabel,
@@ -308,7 +303,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// view data that will be merged into the <see cref="ViewDataDictionary{TModel}"/> instance created for the
         /// template.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// <para>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
@@ -319,7 +314,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <c>"prop"</c> which identifies the current model's "prop" property.
         /// </para>
         /// </remarks>
-        HtmlString Editor(string expression, string templateName, string htmlFieldName, object additionalViewData);
+        IHtmlContent Editor(string expression, string templateName, string htmlFieldName, object additionalViewData);
 
         /// <summary>
         /// Converts the <paramref name="value"/> to an HTML-encoded <see cref="string"/>.
@@ -417,7 +412,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -445,7 +440,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        HtmlString Hidden(string expression, object value, object htmlAttributes);
+        IHtmlContent Hidden(string expression, object value, object htmlAttributes);
 
         /// <summary>
         /// Returns the HTML element Id for the specified <paramref name="expression"/>.
@@ -463,8 +458,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        HtmlString Label(string expression, string labelText, object htmlAttributes);
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        IHtmlContent Label(string expression, string labelText, object htmlAttributes);
 
         /// <summary>
         /// Returns a multi-selection &lt;select&gt; element for the <paramref name="expression"/>, using the
@@ -479,13 +474,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the &lt;select&gt; element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
         /// &lt;select&gt; element's "name" attribute. Sanitizes <paramref name="expression"/> to set element's "id"
         /// attribute.
         /// </remarks>
-        HtmlString ListBox(string expression, IEnumerable<SelectListItem> selectList, object htmlAttributes);
+        IHtmlContent ListBox(string expression, IEnumerable<SelectListItem> selectList, object htmlAttributes);
 
         /// <summary>
         /// Returns the full HTML element name for the specified <paramref name="expression"/>.
@@ -517,7 +512,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -531,7 +526,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        HtmlString Password(string expression, object value, object htmlAttributes);
+        IHtmlContent Password(string expression, object value, object htmlAttributes);
 
         /// <summary>
         /// Returns an &lt;input&gt; element of type "radio" for the specified <paramref name="expression"/>.
@@ -551,7 +546,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -591,23 +586,23 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// the attribute otherwise.
         /// </para>
         /// </remarks>
-        HtmlString RadioButton(string expression, object value, bool? isChecked, object htmlAttributes);
+        IHtmlContent RadioButton(string expression, object value, bool? isChecked, object htmlAttributes);
 
         /// <summary>
         /// Wraps HTML markup in an <see cref="HtmlString"/>, without HTML-encoding the specified
         /// <paramref name="value"/>.
         /// </summary>
         /// <param name="value">HTML markup <see cref="string"/>.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the wrapped <see cref="string"/>.</returns>
-        HtmlString Raw(string value);
+        /// <returns>A new <see cref="IHtmlContent"/> containing the wrapped <see cref="string"/>.</returns>
+        IHtmlContent Raw(string value);
 
         /// <summary>
         /// Wraps HTML markup from the string representation of an <see cref="object"/> in an
         /// <see cref="HtmlString"/>, without HTML-encoding the string representation.
         /// </summary>
         /// <param name="value">The <see cref="object"/> to wrap.</param>
-        /// <returns>A new <see cref="HtmlString"/> containing the wrapped string representation.</returns>
-        HtmlString Raw(object value);
+        /// <returns><see cref="IHtmlContent"/> containing the wrapped string representation.</returns>
+        IHtmlContent Raw(object value);
 
         /// <summary>
         /// Renders HTML markup for the specified partial view.
@@ -641,8 +636,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the anchor element.</returns>
-        HtmlString RouteLink(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the anchor element.</returns>
+        IHtmlContent RouteLink(
             [NotNull] string linkText,
             string routeName,
             string protocol,
@@ -662,7 +657,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;textarea&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;textarea&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="expression"/> to set
@@ -689,7 +684,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        HtmlString TextArea(string expression, string value, int rows, int columns, object htmlAttributes);
+        IHtmlContent TextArea(string expression, string value, int rows, int columns, object htmlAttributes);
 
         /// <summary>
         /// Returns an &lt;input&gt; element of type "text" for the specified <paramref name="current"/>.
@@ -703,7 +698,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and <paramref name="current"/> to set
@@ -737,7 +732,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        HtmlString TextBox(string current, object value, string format, object htmlAttributes);
+        IHtmlContent TextBox(string current, object value, string format, object htmlAttributes);
 
         /// <summary>
         /// Returns the validation message if an error exists in the <see cref="ModelStateDictionary"/> object
@@ -758,10 +753,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="ViewContext.ValidationMessageElement"/>.
         /// </param>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing a <paramref name="tag"/> element. <c>null</c> if the
+        /// A new <see cref="IHtmlContent"/> containing a <paramref name="tag"/> element. <c>null</c> if the
         /// <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
-        HtmlString ValidationMessage(string expression, string message, object htmlAttributes, string tag);
+        IHtmlContent ValidationMessage(string expression, string message, object htmlAttributes, string tag);
 
         /// <summary>
         /// Returns an unordered list (&lt;ul&gt; element) of validation messages that are in the
@@ -780,11 +775,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="ViewContext.ValidationSummaryMessageElement" />.
         /// </param>
         /// <returns>
-        /// New <see cref="HtmlString"/> containing a &lt;div&gt; element wrapping the <paramref name="tag"/> element
+        /// New <see cref="IHtmlContent"/> containing a &lt;div&gt; element wrapping the <paramref name="tag"/> element
         /// and the &lt;ul&gt; element. <see cref="HtmlString.Empty"/> if the current model is valid and client-side
         /// validation is disabled).
         /// </returns>
-        HtmlString ValidationSummary(
+        IHtmlContent ValidationSummary(
             bool excludePropertyErrors,
             string message,
             object htmlAttributes,

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/IHtmlHelperOfT.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -28,7 +29,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// An <see cref="object"/> that contains the HTML attributes for the checkbox element. Alternatively, an
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; elements.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; elements.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -53,7 +54,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// if the <see cref="bool"/> values is <c>true</c>; does not include the attribute otherwise.
         /// </para>
         /// </remarks>
-        HtmlString CheckBoxFor([NotNull] Expression<Func<TModel, bool>> expression, object htmlAttributes);
+        IHtmlContent CheckBoxFor([NotNull] Expression<Func<TModel, bool>> expression, object htmlAttributes);
 
         /// <summary>
         /// Returns HTML markup for the <paramref name="expression"/>, using a display template, specified HTML field
@@ -72,12 +73,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// template.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the created HTML.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the created HTML.</returns>
         /// <remarks>
         /// For example the default <see cref="object"/> display template includes markup for each property in the
         /// <paramref name="expression"/> result.
         /// </remarks>
-        HtmlString DisplayFor<TResult>(
+        IHtmlContent DisplayFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName,
             string htmlFieldName,
@@ -131,13 +132,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
         /// <paramref name="expression"/> to set &lt;select&gt; element's "name" attribute. Sanitizes the string
         /// representation of the <paramref name="expression"/> to set element's "id" attribute.
         /// </remarks>
-        HtmlString DropDownListFor<TResult>(
+        IHtmlContent DropDownListFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             IEnumerable<SelectListItem> selectList,
             string optionLabel,
@@ -160,12 +161,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// template.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element(s).</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element(s).</returns>
         /// <remarks>
         /// For example the default <see cref="object"/> editor template includes &lt;label&gt; and &lt;input&gt;
         /// elements for each property in the <paramref name="expression"/> result.
         /// </remarks>
-        HtmlString EditorFor<TResult>(
+        IHtmlContent EditorFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string templateName,
             string htmlFieldName,
@@ -186,7 +187,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -207,7 +208,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        HtmlString HiddenFor<TResult>(
+        IHtmlContent HiddenFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object htmlAttributes);
 
@@ -229,8 +230,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;label&gt; element.</returns>
-        HtmlString LabelFor<TResult>(
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;label&gt; element.</returns>
+        IHtmlContent LabelFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string labelText,
             object htmlAttributes);
@@ -249,13 +250,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;select&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;select&gt; element.</returns>
         /// <remarks>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
         /// <paramref name="expression"/> to set &lt;select&gt; element's "name" attribute. Sanitizes the string
         /// representation of the <paramref name="expression"/> to set element's "id" attribute.
         /// </remarks>
-        HtmlString ListBoxFor<TResult>(
+        IHtmlContent ListBoxFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             IEnumerable<SelectListItem> selectList,
             object htmlAttributes);
@@ -277,7 +278,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -294,7 +295,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        HtmlString PasswordFor<TResult>(
+        IHtmlContent PasswordFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             object htmlAttributes);
 
@@ -308,7 +309,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -334,16 +335,16 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <paramref name="value"/>; does not include the attribute otherwise.
         /// </para>
         /// </remarks>
-        HtmlString RadioButtonFor<TResult>(
+        IHtmlContent RadioButtonFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             [NotNull] object value,
             object htmlAttributes);
 
         /// <inheritdoc cref="IHtmlHelper.Raw(object)"/>
-        new HtmlString Raw(object value);
+        new IHtmlContent Raw(object value);
 
         /// <inheritdoc cref="IHtmlHelper.Raw(string)"/>
-        new HtmlString Raw(string value);
+        new IHtmlContent Raw(string value);
 
         /// <summary>
         /// Returns a &lt;textarea&gt; element for the specified <paramref name="expression"/>.
@@ -356,7 +357,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;textarea&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;textarea&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -375,7 +376,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        HtmlString TextAreaFor<TResult>(
+        IHtmlContent TextAreaFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             int rows,
             int columns,
@@ -393,7 +394,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
-        /// <returns>A new <see cref="HtmlString"/> containing the &lt;input&gt; element.</returns>
+        /// <returns>A new <see cref="IHtmlContent"/> containing the &lt;input&gt; element.</returns>
         /// <remarks>
         /// <para>
         /// Combines <see cref="TemplateInfo.HtmlFieldPrefix"/> and the string representation of the
@@ -415,7 +416,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <item>Otherwise, <c>string.Empty</c>.</item>
         /// </list>
         /// </remarks>
-        HtmlString TextBoxFor<TResult>(
+        IHtmlContent TextBoxFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string format,
             object htmlAttributes);
@@ -440,10 +441,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </param>
         /// <typeparam name="TResult">The type of the <paramref name="expression"/> result.</typeparam>
         /// <returns>
-        /// A new <see cref="HtmlString"/> containing the <paramref name="tag"/> element. <c>null</c> if the
+        /// A new <see cref="IHtmlContent"/> containing the <paramref name="tag"/> element. <c>null</c> if the
         /// <paramref name="expression"/> is valid and client-side validation is disabled.
         /// </returns>
-        HtmlString ValidationMessageFor<TResult>(
+        IHtmlContent ValidationMessageFor<TResult>(
             [NotNull] Expression<Func<TModel, TResult>> expression,
             string message,
             object htmlAttributes,

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Internal/TemplateBuilder.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Globalization;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.Framework.Internal;
 
@@ -42,7 +43,7 @@ namespace Microsoft.AspNet.Mvc.Rendering.Internal
             _metadata = modelExplorer.Metadata;
         }
 
-        public string Build()
+        public IHtmlContent Build()
         {
             if (_metadata.ConvertEmptyStringToNull && string.Empty.Equals(_model))
             {
@@ -66,7 +67,7 @@ namespace Microsoft.AspNet.Mvc.Rendering.Internal
             // don't check to make sure that the object hasn't already been displayed
             if (_viewData.TemplateInfo.Visited(_modelExplorer))
             {
-                return string.Empty;
+                return HtmlString.Empty;
             }
 
             // We need to copy the ModelExplorer to copy the model metadata. Otherwise we might

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/Internal/TemplateRenderer.cs

@@ -4,10 +4,9 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Globalization;
-using System.IO;
 using System.Linq;
 using System.Reflection;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Http;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.ViewFeatures;
@@ -22,8 +21,8 @@ namespace Microsoft.AspNet.Mvc.Rendering.Internal
         private const string EditorTemplateViewPath = "EditorTemplates";
         public const string IEnumerableOfIFormFileName = "IEnumerable`" + nameof(IFormFile);
 
-        private static readonly Dictionary<string, Func<IHtmlHelper, string>> _defaultDisplayActions =
-            new Dictionary<string, Func<IHtmlHelper, string>>(StringComparer.OrdinalIgnoreCase)
+        private static readonly Dictionary<string, Func<IHtmlHelper, IHtmlContent>> _defaultDisplayActions =
+            new Dictionary<string, Func<IHtmlHelper, IHtmlContent>>(StringComparer.OrdinalIgnoreCase)
             {
                 { "Collection", DefaultDisplayTemplates.CollectionTemplate },
                 { "EmailAddress", DefaultDisplayTemplates.EmailAddressTemplate },
@@ -37,8 +36,8 @@ namespace Microsoft.AspNet.Mvc.Rendering.Internal
                 { typeof(object).Name, DefaultDisplayTemplates.ObjectTemplate },
             };
 
-        private static readonly Dictionary<string, Func<IHtmlHelper, string>> _defaultEditorActions =
-            new Dictionary<string, Func<IHtmlHelper, string>>(StringComparer.OrdinalIgnoreCase)
+        private static readonly Dictionary<string, Func<IHtmlHelper, IHtmlContent>> _defaultEditorActions =
+            new Dictionary<string, Func<IHtmlHelper, IHtmlContent>>(StringComparer.OrdinalIgnoreCase)
             {
                 { "Collection", DefaultEditorTemplates.CollectionTemplate },
                 { "EmailAddress", DefaultEditorTemplates.EmailAddressInputTemplate },
@@ -88,7 +87,7 @@ namespace Microsoft.AspNet.Mvc.Rendering.Internal
             _readOnly = readOnly;
         }
 
-        public string Render()
+        public IHtmlContent Render()
         {
             var defaultActions = GetDefaultActions();
             var modeViewPath = _readOnly ? DisplayTemplateViewPath : EditorTemplateViewPath;
@@ -100,7 +99,7 @@ namespace Microsoft.AspNet.Mvc.Rendering.Internal
                 var viewEngineResult = _viewEngine.FindPartialView(_viewContext, fullViewName);
                 if (viewEngineResult.Success)
                 {
-                    using (var writer = new StringWriter(CultureInfo.InvariantCulture))
+                    using (var writer = new StringCollectionTextWriter(_viewContext.Writer.Encoding))
                     {
                         // Forcing synchronous behavior so users don't have to await templates.
                         var view = viewEngineResult.View;
@@ -109,12 +108,12 @@ namespace Microsoft.AspNet.Mvc.Rendering.Internal
                             var viewContext = new ViewContext(_viewContext, viewEngineResult.View, _viewData, writer);
                             var renderTask = viewEngineResult.View.RenderAsync(viewContext);
                             renderTask.GetAwaiter().GetResult();
-                            return writer.ToString();
+                            return writer.Content;
                         }
                     }
                 }
 
-                Func<IHtmlHelper, string> defaultAction;
+                Func<IHtmlHelper, IHtmlContent> defaultAction;
                 if (defaultActions.TryGetValue(viewName, out defaultAction))
                 {
                     return defaultAction(MakeHtmlHelper(_viewContext, _viewData));
@@ -125,7 +124,7 @@ namespace Microsoft.AspNet.Mvc.Rendering.Internal
                 Resources.FormatTemplateHelpers_NoTemplate(_viewData.ModelExplorer.ModelType.FullName));
         }
 
-        private Dictionary<string, Func<IHtmlHelper, string>> GetDefaultActions()
+        private Dictionary<string, Func<IHtmlHelper, IHtmlContent>> GetDefaultActions()
         {
             return _readOnly ? _defaultDisplayActions : _defaultEditorActions;
         }

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/StringCollectionTextWriter.cs

@@ -172,7 +172,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// <inheritdoc />
         public override string ToString()
         {
-            return string.Join(string.Empty, Content);
+            using (var writer = new StringWriter())
+            {
+                Content.WriteTo(writer, HtmlEncoder.Default);
+                return writer.ToString();
+            }
         }
     }
 }

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/StringHtmlContent.cs

@@ -0,0 +1,39 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.IO;
+using Microsoft.AspNet.Html.Abstractions;
+using Microsoft.Framework.Internal;
+using Microsoft.Framework.WebEncoders;
+
+namespace Microsoft.AspNet.Mvc.Rendering
+{
+    /// <summary>
+    /// String content which gets encoded when written.
+    /// </summary>
+    public class StringHtmlContent : IHtmlContent
+    {
+        private readonly string _input;
+
+        /// <summary>
+        /// Creates a new instance of <see cref="StringHtmlContent"/>
+        /// </summary>
+        /// <param name="input"><see cref="string"/> to be HTML encoded when <see cref="WriteTo"/> is called.</param>
+        public StringHtmlContent(string input)
+        {
+            _input = input;
+        }
+
+        /// <inheritdoc />
+        public void WriteTo([NotNull] TextWriter writer, [NotNull] IHtmlEncoder encoder)
+        {
+            encoder.HtmlEncode(_input, writer);
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return _input;
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.ViewFeatures/project.json

@@ -15,6 +15,7 @@
         "Microsoft.AspNet.Mvc.Core": "6.0.0-*",
         "Microsoft.AspNet.Mvc.DataAnnotations": "6.0.0-*",
         "Microsoft.AspNet.Mvc.Formatters.Json": "6.0.0-*",
+        "Microsoft.Framework.BufferedHtmlContent.Sources": { "version": "1.0.0-*", "type": "build" },
         "Microsoft.Framework.ClosedGenericMatcher.Sources": { "version": "1.0.0-*", "type": "build" },
         "Microsoft.Framework.CopyOnWriteDictionary.Sources": { "version": "1.0.0-*", "type": "build" },
         "Microsoft.Framework.NotNullAttribute.Sources": { "version": "1.0.0-*", "type": "build" },

test/Microsoft.AspNet.Mvc.ApiExplorer.Test/project.json

@@ -8,6 +8,7 @@
     "Microsoft.AspNet.Mvc.Formatters.Xml": "6.0.0-*",
     "Microsoft.AspNet.Testing": "1.0.0-*",
     "Microsoft.Framework.Logging.Testing": "1.0.0-*",
+    "Microsoft.Framework.WebEncoders.Testing": "1.0.0-*",
     "Moq": "4.2.1312.1622",
     "xunit.runner.aspnet": "2.0.0-aspnet-*"
   },

test/Microsoft.AspNet.Mvc.FunctionalTests/project.json

@@ -45,6 +45,7 @@
         "Microsoft.AspNet.TestHost": "1.0.0-*",
         "Microsoft.AspNet.WebUtilities": "1.0.0-*",
         "Microsoft.Framework.Configuration.Json": "1.0.0-*",
+        "Microsoft.Framework.WebEncoders.Testing": "1.0.0-*",
         "ModelBindingWebSite": "1.0.0",
         "MvcSample.Web": "1.0.0",
         "PrecompilationWebSite": "1.0.0",

test/Microsoft.AspNet.Mvc.IntegrationTests/project.json

@@ -10,6 +10,7 @@
             "type": "build"
         },
         "Microsoft.AspNet.Testing": "1.0.0-*",
+        "Microsoft.Framework.WebEncoders.Testing": "1.0.0-*",
         "xunit.runner.aspnet": "2.0.0-aspnet-*"
     },
     "commands": {

test/Microsoft.AspNet.Mvc.Razor.Host.Test/project.json

@@ -8,6 +8,7 @@
     "Microsoft.AspNet.Mvc.ViewFeatures": "6.0.0-*",
     "Microsoft.AspNet.Mvc.TestCommon": { "version": "6.0.0-*", "type": "build" },
     "Microsoft.AspNet.Testing": "1.0.0-*",
+    "Microsoft.Framework.WebEncoders.Testing": "1.0.0-*",
     "xunit.runner.aspnet": "2.0.0-aspnet-*"
   },
   "commands": {

test/Microsoft.AspNet.Mvc.Razor.Test/RazorPageTest.cs

@@ -4,11 +4,11 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Http.Internal;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.PageExecutionInstrumentation;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
 using Microsoft.AspNet.Testing;
@@ -181,7 +181,9 @@ namespace Microsoft.AspNet.Mvc.Razor
                 // Assert
                 var content = Assert.IsType<DefaultTagHelperContent>(returnValue);
                 Assert.Equal("HtmlEncode[[Hello ]]HtmlEncode[[World!]]", content.GetContent());
-                Assert.Equal(new[] { "HtmlEncode[[Hello ]]", "HtmlEncode[[World!]]" }, content.ToArray());
+                Assert.Equal(
+                    "HtmlEncode[[Hello ]]HtmlEncode[[World!]]",
+                    HtmlContentUtilities.HtmlContentToString(content));
             }, viewContext);
             await page.ExecuteAsync();
         }

test/Microsoft.AspNet.Mvc.TagHelpers.Test/AnchorTagHelperTest.cs

@@ -114,7 +114,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     "hello=world",
                     It.IsAny<IDictionary<string, object>>(),
                     null))
-                .Returns(new TagBuilder("a", new CommonTestEncoder()))
+                .Returns(new TagBuilder("a"))
                 .Verifiable();
             var anchorTagHelper = new AnchorTagHelper(generator.Object)
             {
@@ -163,7 +163,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     "hello=world",
                     It.IsAny<IDictionary<string, object>>(),
                     null))
-                .Returns(new TagBuilder("a", new CommonTestEncoder()))
+                .Returns(new TagBuilder("a"))
                 .Verifiable();
             var anchorTagHelper = new AnchorTagHelper(generator.Object)
             {

test/Microsoft.AspNet.Mvc.TagHelpers.Test/FormTagHelperTest.cs

@@ -121,7 +121,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     It.IsAny<object>(),
                     It.IsAny<string>(),
                     It.IsAny<object>()))
-                .Returns(new TagBuilder("form", new CommonTestEncoder()));
+                .Returns(new TagBuilder("form"));
 
             generator.Setup(mock => mock.GenerateAntiforgery(viewContext))
                      .Returns(new HtmlString("<input />"));
@@ -189,7 +189,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                         routeValue = Assert.Single(routeValueDictionary, attr => attr.Key.Equals("-Name"));
                         Assert.Equal("Value", routeValue.Value);
                     })
-                .Returns(new TagBuilder("form", new CommonTestEncoder()))
+                .Returns(new TagBuilder("form"))
                 .Verifiable();
             var formTagHelper = new FormTagHelper(generator.Object)
             {
@@ -244,7 +244,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     It.IsAny<IDictionary<string, object>>(),
                     null,
                     null))
-                .Returns(new TagBuilder("form", new CommonTestEncoder()))
+                .Returns(new TagBuilder("form"))
                 .Verifiable();
             var formTagHelper = new FormTagHelper(generator.Object)
             {
@@ -294,7 +294,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     It.Is<Dictionary<string, object>>(m => string.Equals(m["name"], "value")),
                     null,
                     null))
-                .Returns(new TagBuilder("form", new CommonTestEncoder()))
+                .Returns(new TagBuilder("form"))
                 .Verifiable();
             var formTagHelper = new FormTagHelper(generator.Object)
             {

test/Microsoft.AspNet.Mvc.TagHelpers.Test/InputTagHelperTest.cs

@@ -4,12 +4,15 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
+using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Http;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.AspNet.Mvc.Rendering.Internal;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
 using Microsoft.Framework.WebEncoders.Testing;
 using Moq;
@@ -104,7 +107,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
 
             // Assert
             Assert.Empty(output.Attributes); // Moved to Content and cleared
-            Assert.Equal(expectedContent, output.Content.GetContent());
+            Assert.Equal(expectedContent, HtmlContentUtilities.HtmlContentToString(output.Content));
             Assert.True(output.SelfClosing);
             Assert.Null(output.TagName); // Cleared
         }
@@ -276,7 +279,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
 
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var tagHelper = GetTagHelper(htmlGenerator.Object, model: false, propertyName: nameof(Model.IsACar));
-            var tagBuilder = new TagBuilder("input", new CommonTestEncoder())
+            var tagBuilder = new TagBuilder("input")
             {
                 Attributes =
                 {
@@ -297,7 +300,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelper.ViewContext,
                     tagHelper.For.ModelExplorer,
                     tagHelper.For.Name))
-                .Returns(new TagBuilder("hidden", new NullTestEncoder()))
+                .Returns(new TagBuilder("hidden"))
                 .Verifiable();
 
             // Act
@@ -308,7 +311,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
 
             Assert.Empty(output.Attributes);    // Moved to Content and cleared
             Assert.Equal(expectedPreContent, output.PreContent.GetContent());
-            Assert.Equal(expectedContent, output.Content.GetContent());
+            Assert.Equal(expectedContent, HtmlContentUtilities.HtmlContentToString(output.Content));
             Assert.Equal(expectedPostContent, output.PostContent.GetContent());
             Assert.True(output.SelfClosing);
             Assert.Null(output.TagName);       // Cleared
@@ -381,7 +384,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 metadataProvider: metadataProvider);
             tagHelper.InputTypeName = inputTypeName;
 
-            var tagBuilder = new TagBuilder("input", new NullTestEncoder())
+            var tagBuilder = new TagBuilder("input")
             {
                 Attributes =
                 {
@@ -480,7 +483,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 metadataProvider: metadataProvider);
             tagHelper.InputTypeName = inputTypeName;
 
-            var tagBuilder = new TagBuilder("input", new NullTestEncoder())
+            var tagBuilder = new TagBuilder("input")
             {
                 Attributes =
                 {
@@ -570,7 +573,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             tagHelper.InputTypeName = inputTypeName;
             tagHelper.Value = value;
 
-            var tagBuilder = new TagBuilder("input", new NullTestEncoder())
+            var tagBuilder = new TagBuilder("input")
             {
                 Attributes =
                 {
@@ -683,7 +686,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 metadataProvider: metadataProvider);
             tagHelper.InputTypeName = inputTypeName;
 
-            var tagBuilder = new TagBuilder("input", new NullTestEncoder())
+            var tagBuilder = new TagBuilder("input")
             {
                 Attributes =
                 {
@@ -791,7 +794,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 propertyName: nameof(Model.Text),
                 metadataProvider: metadataProvider);
 
-            var tagBuilder = new TagBuilder("input", new NullTestEncoder());
+            var tagBuilder = new TagBuilder("input");
 
             var htmlAttributes = new Dictionary<string, object>
             {
@@ -820,9 +823,9 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
 
             Assert.True(output.SelfClosing);
             Assert.Equal(expectedAttributes, output.Attributes);
-            Assert.Empty(output.PreContent);
-            Assert.Equal(new[] { string.Empty }, output.Content);
-            Assert.Empty(output.PostContent);
+            Assert.Empty(output.PreContent.GetContent());
+            Assert.Equal(string.Empty, output.Content.GetContent());
+            Assert.Empty(output.PostContent.GetContent());
             Assert.Equal(expectedTagName, output.TagName);
         }
 
@@ -875,7 +878,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 metadataProvider: metadataProvider);
             tagHelper.ViewContext.Html5DateRenderingMode = dateRenderingMode;
 
-            var tagBuilder = new TagBuilder("input", new NullTestEncoder());
+            var tagBuilder = new TagBuilder("input");
             htmlGenerator
                 .Setup(mock => mock.GenerateTextBox(
                     tagHelper.ViewContext,
@@ -895,9 +898,9 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
 
             Assert.True(output.SelfClosing);
             Assert.Equal(expectedAttributes, output.Attributes);
-            Assert.Empty(output.PreContent);
-            Assert.Equal(new[] { string.Empty }, output.Content);
-            Assert.Empty(output.PostContent);
+            Assert.Empty(output.PreContent.GetContent());
+            Assert.Equal(string.Empty, output.Content.GetContent());
+            Assert.Empty(output.PostContent.GetContent());
             Assert.Equal(expectedTagName, output.TagName);
         }
 

test/Microsoft.AspNet.Mvc.TagHelpers.Test/LabelTagHelperTest.cs

@@ -7,6 +7,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
 using Xunit;
 
@@ -222,7 +223,9 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Assert
             Assert.Equal(expectedAttributes, output.Attributes);
             Assert.Equal(expectedPreContent, output.PreContent.GetContent());
-            Assert.Equal(tagHelperOutputContent.ExpectedContent, output.Content.GetContent());
+            Assert.Equal(
+                tagHelperOutputContent.ExpectedContent,
+                HtmlContentUtilities.HtmlContentToString(output.Content));
             Assert.Equal(expectedPostContent, output.PostContent.GetContent());
             Assert.False(output.SelfClosing);
             Assert.Equal(expectedTagName, output.TagName);

test/Microsoft.AspNet.Mvc.TagHelpers.Test/SelectTagHelperTest.cs

@@ -8,6 +8,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
 using Moq;
 using Xunit;
@@ -334,7 +335,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             Assert.Equal(expectedAttributes, output.Attributes);
             Assert.Equal(expectedPreContent, output.PreContent.GetContent());
             Assert.Equal(expectedContent, output.Content.GetContent());
-            Assert.Equal(expectedPostContent, output.PostContent.GetContent());
+            Assert.Equal(expectedPostContent, HtmlContentUtilities.HtmlContentToString(output.PostContent));
             Assert.Equal(expectedTagName, output.TagName);
 
             Assert.NotNull(viewContext.FormContext?.FormData);
@@ -437,7 +438,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             Assert.Equal(expectedAttributes, output.Attributes);
             Assert.Equal(expectedPreContent, output.PreContent.GetContent());
             Assert.Equal(expectedContent, output.Content.GetContent());
-            Assert.Equal(expectedPostContent, output.PostContent.GetContent());
+            Assert.Equal(expectedPostContent, HtmlContentUtilities.HtmlContentToString(output.PostContent));
             Assert.Equal(expectedTagName, output.TagName);
 
             Assert.NotNull(viewContext.FormContext?.FormData);

test/Microsoft.AspNet.Mvc.TagHelpers.Test/TagHelperOutputExtensionsTest.cs

@@ -425,7 +425,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput("p", outputAttributes);
 
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             foreach (var attr in tagBuilderAttributes)
             {
                 tagBuilder.Attributes.Add(attr.Key, attr.Value);
@@ -451,7 +451,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var expectedAttribute = new TagHelperAttribute("type", "btn");
             tagHelperOutput.Attributes.Add(expectedAttribute);
 
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             tagBuilder.Attributes.Add("type", "hello");
 
             // Act
@@ -471,7 +471,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 attributes: new TagHelperAttributeList());
             tagHelperOutput.Attributes.Add("class", "Hello");
 
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             tagBuilder.Attributes.Add("class", "btn");
 
             var expectedAttribute = new TagHelperAttribute("class", "Hello btn");
@@ -497,7 +497,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 attributes: new TagHelperAttributeList());
             tagHelperOutput.Attributes.Add(originalName, "Hello");
 
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             tagBuilder.Attributes.Add(updateName, "btn");
 
             // Act
@@ -516,7 +516,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 "p",
                 attributes: new TagHelperAttributeList());
 
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             var expectedAttribute = new TagHelperAttribute("visible", "val < 3");
             tagBuilder.Attributes.Add("visible", "val < 3");
 
@@ -536,7 +536,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 "p",
                 attributes: new TagHelperAttributeList());
 
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             var expectedAttribute1 = new TagHelperAttribute("class", "btn");
             var expectedAttribute2 = new TagHelperAttribute("class2", "btn");
             tagBuilder.Attributes.Add("class", "btn");
@@ -563,7 +563,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var expectedAttribute = new TagHelperAttribute("class", "btn");
             tagHelperOutput.Attributes.Add(expectedAttribute);
 
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
 
             // Act
             tagHelperOutput.MergeAttributes(tagBuilder);
@@ -583,7 +583,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var expectedOutputAttribute = new TagHelperAttribute("class", "btn");
             tagHelperOutput.Attributes.Add(expectedOutputAttribute);
 
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             var expectedBuilderAttribute = new TagHelperAttribute("for", "hello");
             tagBuilder.Attributes.Add("for", "hello");
 

test/Microsoft.AspNet.Mvc.TagHelpers.Test/TestableHtmlGenerator.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.IO;
 using Microsoft.AspNet.Antiforgery;
 using Microsoft.AspNet.DataProtection;
+using Microsoft.AspNet.Html.Abstractions;
 using Microsoft.AspNet.Http.Internal;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
@@ -70,9 +71,9 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             return viewContext;
         }
 
-        public override HtmlString GenerateAntiforgery(ViewContext viewContext)
+        public override IHtmlContent GenerateAntiforgery(ViewContext viewContext)
         {
-            var tagBuilder = new TagBuilder("input", new CommonTestEncoder())
+            var tagBuilder = new TagBuilder("input")
             {
                 Attributes =
                 {
@@ -82,7 +83,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 },
             };
 
-            return tagBuilder.ToHtmlString(TagRenderMode.SelfClosing);
+            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
         }
 
         protected override IDictionary<string, object> GetValidationAttributes(

test/Microsoft.AspNet.Mvc.TagHelpers.Test/TextAreaTagHelperTest.cs

@@ -7,6 +7,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
 using Xunit;
 
@@ -46,32 +47,32 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 {
                     { null, typeof(Model), null,
                         new NameAndId("Text", "Text"),
-                        Environment.NewLine + "HtmlEncode[[]]" },
+                        Environment.NewLine },
 
                     { modelWithNull, typeof(Model), modelWithNull.Text,
                         new NameAndId("Text", "Text"),
-                        Environment.NewLine + "HtmlEncode[[]]" },
+                        Environment.NewLine },
                     { modelWithText, typeof(Model), modelWithText.Text,
                         new NameAndId("Text", "Text"),
                         Environment.NewLine + "HtmlEncode[[outer text]]" },
 
                     { modelWithNull, typeof(NestedModel), modelWithNull.NestedModel.Text,
                         new NameAndId("NestedModel.Text", "NestedModel_Text"),
-                        Environment.NewLine + "HtmlEncode[[]]" },
+                        Environment.NewLine },
                     { modelWithText, typeof(NestedModel), modelWithText.NestedModel.Text,
                         new NameAndId("NestedModel.Text", "NestedModel_Text"),
                         Environment.NewLine + "HtmlEncode[[inner text]]" },
 
                     { models, typeof(Model), models[0].Text,
                         new NameAndId("[0].Text", "z0__Text"),
-                        Environment.NewLine + "HtmlEncode[[]]" },
+                        Environment.NewLine },
                     { models, typeof(Model), models[1].Text,
                         new NameAndId("[1].Text", "z1__Text"),
                         Environment.NewLine + "HtmlEncode[[outer text]]" },
 
                     { models, typeof(NestedModel), models[0].NestedModel.Text,
                         new NameAndId("[0].NestedModel.Text", "z0__NestedModel_Text"),
-                        Environment.NewLine + "HtmlEncode[[]]" },
+                        Environment.NewLine },
                     { models, typeof(NestedModel), models[1].NestedModel.Text,
                         new NameAndId("[1].NestedModel.Text", "z1__NestedModel_Text"),
                         Environment.NewLine + "HtmlEncode[[inner text]]" },
@@ -151,7 +152,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Assert
             Assert.True(output.SelfClosing);
             Assert.Equal(expectedAttributes, output.Attributes);
-            Assert.Equal(expectedContent, output.Content.GetContent());
+            Assert.Equal(expectedContent, HtmlContentUtilities.HtmlContentToString(output.Content));
             Assert.Equal(expectedTagName, output.TagName);
         }
 

test/Microsoft.AspNet.Mvc.TagHelpers.Test/ValidationMessageTagHelperTest.cs

@@ -93,7 +93,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             generator
                 .Setup(mock =>
                     mock.GenerateValidationMessage(expectedViewContext, "Hello", null, null, null))
-                .Returns(new TagBuilder("span", new CommonTestEncoder()))
+                .Returns(new TagBuilder("span"))
                 .Verifiable();
 
             var validationMessageTagHelper = new ValidationMessageTagHelper(generator.Object)
@@ -142,9 +142,9 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             string childContent, string outputContent, string expectedOutputContent)
         {
             // Arrange
-            var tagBuilder = new TagBuilder("span2", new CommonTestEncoder())
+            var tagBuilder = new TagBuilder("span2")
             {
-                InnerHtml = "New HTML"
+                InnerHtml = new HtmlString("New HTML")
             };
             tagBuilder.Attributes.Add("data-foo", "bar");
             tagBuilder.Attributes.Add("data-hello", "world");
@@ -203,9 +203,9 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             string childContent, string expectedOutputContent)
         {
             // Arrange
-            var tagBuilder = new TagBuilder("span2", new CommonTestEncoder())
+            var tagBuilder = new TagBuilder("span2")
             {
-                InnerHtml = "New HTML"
+                InnerHtml = new HtmlString("New HTML")
             };
             tagBuilder.Attributes.Add("data-foo", "bar");
             tagBuilder.Attributes.Add("data-hello", "world");

test/Microsoft.AspNet.Mvc.TagHelpers.Test/ValidationSummaryTagHelperTest.cs

@@ -94,7 +94,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     null,   // message
                     null,   // headerTag
                     null))  // htmlAttributes
-                .Returns(new TagBuilder("div", new HtmlEncoder()))
+                .Returns(new TagBuilder("div"))
                 .Verifiable();
 
             var validationSummaryTagHelper = new ValidationSummaryTagHelper(generator.Object)
@@ -130,9 +130,9 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
         public async Task ProcessAsync_MergesTagBuilderFromGenerateValidationSummary()
         {
             // Arrange
-            var tagBuilder = new TagBuilder("span2", new HtmlEncoder())
+            var tagBuilder = new TagBuilder("span2")
             {
-                InnerHtml = "New HTML"
+                InnerHtml = new HtmlString("New HTML")
             };
 
             tagBuilder.Attributes.Add("data-foo", "bar");
@@ -224,9 +224,9 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
         public async Task ProcessAsync_GeneratesValidationSummaryWhenNotNone(ValidationSummary validationSummary)
         {
             // Arrange
-            var tagBuilder = new TagBuilder("span2", new HtmlEncoder())
+            var tagBuilder = new TagBuilder("span2")
             {
-                InnerHtml = "New HTML"
+                InnerHtml = new HtmlString("New HTML")
             };
 
             var generator = new Mock<IHtmlGenerator>();

test/Microsoft.AspNet.Mvc.TestCommon/HtmlContentUtilities.cs

@@ -0,0 +1,27 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.IO;
+using Microsoft.AspNet.Html.Abstractions;
+using Microsoft.Framework.WebEncoders;
+using Microsoft.Framework.WebEncoders.Testing;
+
+namespace Microsoft.AspNet.Mvc.TestCommon
+{
+    public class HtmlContentUtilities
+    {
+        public static string HtmlContentToString(IHtmlContent content, IHtmlEncoder encoder = null)
+        {
+            if (encoder == null)
+            {
+                encoder = new CommonTestEncoder();
+            }
+
+            using (var writer = new StringWriter())
+            {
+                content.WriteTo(writer, encoder);
+                return writer.ToString();
+            }
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/BufferedHtmlContentTest.cs

@@ -1,127 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System.IO;
-using Microsoft.AspNet.Html.Abstractions;
-using Microsoft.Framework.WebEncoders;
-using Microsoft.Framework.WebEncoders.Testing;
-using Xunit;
-
-namespace Microsoft.AspNet.Mvc.Rendering
-{
-    public class BufferedHtmlContentTest
-    {
-        [Fact]
-        public void AppendString_AppendsAString()
-        {
-            // Arrange
-            var content = new BufferedHtmlContent();
-
-            // Act
-            content.Append("Hello");
-
-            // Assert
-            var result = Assert.Single(content.Entries);
-            Assert.IsType(typeof(string), result);
-        }
-
-        [Fact]
-        public void AppendCharArray_AppendsAsString()
-        {
-            // Arrange
-            var content = new BufferedHtmlContent();
-
-            // Act
-            content.Append(new char[] { 'h', 'e', 'l', 'l', 'o' }, 0, 5);
-
-            // Assert
-            var result = Assert.Single(content.Entries);
-            Assert.IsType(typeof(string), result);
-        }
-
-        [Fact]
-        public void AppendIHtmlContent_AppendsAsIs()
-        {
-            // Arrange
-            var content = new BufferedHtmlContent();
-            var writer = new StringWriter();
-
-            // Act
-            content.Append(new TestHtmlContent("Hello"));
-
-            // Assert
-            var result = Assert.Single(content.Entries);
-            var testHtmlContent = Assert.IsType<TestHtmlContent>(result);
-            testHtmlContent.WriteTo(writer, new CommonTestEncoder());
-            Assert.Equal("Written from TestHtmlContent: Hello", writer.ToString());
-        }
-
-        [Fact]
-        public void CanAppendMultipleItems()
-        {
-            // Arrange
-            var content = new BufferedHtmlContent();
-
-            // Act
-            content.Append(new TestHtmlContent("hello"));
-            content.Append("Test");
-
-            // Assert
-            Assert.Equal(2, content.Entries.Count);
-            Assert.Equal("Written from TestHtmlContent: hello", content.Entries[0].ToString());
-            Assert.Equal("Test", content.Entries[1]);
-        }
-
-        [Fact]
-        public void Clear_DeletesAllItems()
-        {
-            // Arrange
-            var content = new BufferedHtmlContent();
-            content.Append(new TestHtmlContent("hello"));
-            content.Append("Test");
-
-            // Act
-            content.Clear();
-
-            // Assert
-            Assert.Equal(0, content.Entries.Count);
-        }
-
-        [Fact]
-        public void WriteTo_WritesAllItems()
-        {
-            // Arrange
-            var content = new BufferedHtmlContent();
-            var writer = new StringWriter();
-            content.Append(new TestHtmlContent("Hello"));
-            content.Append("Test");
-
-            // Act
-            content.WriteTo(writer, new CommonTestEncoder());
-
-            // Assert
-            Assert.Equal(2, content.Entries.Count);
-            Assert.Equal("Written from TestHtmlContent: HelloTest", writer.ToString());
-        }
-
-        private class TestHtmlContent : IHtmlContent
-        {
-            private string _content;
-
-            public TestHtmlContent(string content)
-            {
-                _content = content;
-            }
-
-            public void WriteTo(TextWriter writer, IHtmlEncoder encoder)
-            {
-                writer.Write(ToString());
-            }
-
-            public override string ToString()
-            {
-                return "Written from TestHtmlContent: " + _content;
-            }
-        }
-    }
-}

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/DefaultDisplayTemplatesTest.cs

@@ -10,6 +10,7 @@ using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Moq;
 using Xunit;
 
@@ -63,7 +64,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultDisplayTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -82,7 +83,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultDisplayTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal("(null value)", result);
+            Assert.Equal("(null value)", HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -112,7 +113,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultDisplayTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(expectedResult, result);
+            Assert.Equal(expectedResult, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -121,9 +122,9 @@ namespace Microsoft.AspNet.Mvc.Core
             // Arrange
             var expected =
 @"<div class=""HtmlEncode[[display-label]]"">HtmlEncode[[Property1]]</div>
-<div class=""HtmlEncode[[display-field]]"">HtmlEncode[[]]</div>
+<div class=""HtmlEncode[[display-field]]""></div>
 <div class=""HtmlEncode[[display-label]]"">HtmlEncode[[Property3]]</div>
-<div class=""HtmlEncode[[display-field]]"">HtmlEncode[[]]</div>
+<div class=""HtmlEncode[[display-field]]""></div>
 ";
             var model = new DefaultTemplatesUtilities.ObjectWithScaffoldColumn();
             var viewEngine = new Mock<ICompositeViewEngine>();
@@ -135,7 +136,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultDisplayTemplates.ObjectTemplate(htmlHelper);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -162,7 +163,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultDisplayTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -204,7 +205,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultDisplayTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -223,7 +224,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultDisplayTemplates.HiddenInputTemplate(html);
 
             // Assert
-            Assert.Equal("HtmlEncode[[Formatted string]]", result);
+            Assert.Equal("HtmlEncode[[Formatted string]]", HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -249,7 +250,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultDisplayTemplates.HiddenInputTemplate(html);
 
             // Assert
-            Assert.Empty(result);
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -268,7 +269,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = helper.Display("Property1");
 
             // Assert
-            Assert.Equal("HtmlEncode[[ViewData string]]", result.ToString());
+            Assert.Equal("HtmlEncode[[ViewData string]]", HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -287,7 +288,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = helper.DisplayFor(m => m.Property1);
 
             // Assert
-            Assert.Equal("HtmlEncode[[Model string]]", result.ToString());
+            Assert.Equal("HtmlEncode[[Model string]]", HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -305,7 +306,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = helper.Display("Property1");
 
             // Assert
-            Assert.Equal("HtmlEncode[[Model string]]", result.ToString());
+            Assert.Equal("HtmlEncode[[Model string]]", HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -326,7 +327,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = helper.DisplayFor(m => m.Property1);
 
             // Assert
-            Assert.Equal("HtmlEncode[[]]", result.ToString());
+            Assert.Equal(string.Empty, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/DefaultEditorTemplatesTest.cs

@@ -14,6 +14,7 @@ using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.ModelBinding.Validation;
 using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.AspNet.Mvc.Rendering.Internal;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Testing;
 using Microsoft.Framework.Internal;
 using Microsoft.Framework.WebEncoders;
@@ -111,7 +112,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultEditorTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -134,7 +135,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultEditorTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(html.ViewData.ModelMetadata.NullDisplayText, result);
+            Assert.Equal(html.ViewData.ModelMetadata.NullDisplayText, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -167,7 +168,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = DefaultEditorTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(expectedResult, result);
+            Assert.Equal(expectedResult, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -196,7 +197,7 @@ Environment.NewLine;
             var result = DefaultEditorTemplates.ObjectTemplate(htmlHelper);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -226,7 +227,7 @@ Environment.NewLine;
             var result = DefaultEditorTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -270,7 +271,7 @@ Environment.NewLine;
             var result = DefaultEditorTemplates.ObjectTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -292,7 +293,7 @@ Environment.NewLine;
             var result = DefaultEditorTemplates.HiddenInputTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -319,7 +320,7 @@ Environment.NewLine;
             var result = DefaultEditorTemplates.HiddenInputTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -343,7 +344,7 @@ Environment.NewLine;
             var result = DefaultEditorTemplates.MultilineTemplate(html);
 
             // Assert
-            Assert.Equal(expected, result);
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -373,7 +374,7 @@ Environment.NewLine;
                 additionalViewData: null);
 
             // Assert
-            Assert.Equal(expectedResult, result.ToString());
+            Assert.Equal(expectedResult, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -402,7 +403,7 @@ Environment.NewLine;
                 additionalViewData: null);
 
             // Assert
-            Assert.Equal(expectedResult, result.ToString());
+            Assert.Equal(expectedResult, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -441,7 +442,7 @@ Environment.NewLine;
                 additionalViewData: null);
 
             // Assert
-            Assert.Equal(expectedResult, result.ToString());
+            Assert.Equal(expectedResult, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -479,7 +480,7 @@ Environment.NewLine;
                 additionalViewData: null);
 
             // Assert
-            Assert.Equal(expectedResult, result.ToString());
+            Assert.Equal(expectedResult, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -518,7 +519,7 @@ Environment.NewLine;
                 additionalViewData: null);
 
             // Assert
-            Assert.Equal(expectedResult, result.ToString());
+            Assert.Equal(expectedResult, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -556,7 +557,7 @@ Environment.NewLine;
                 additionalViewData: null);
 
             // Assert
-            Assert.Equal(expectedResult, result.ToString());
+            Assert.Equal(expectedResult, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -577,7 +578,7 @@ Environment.NewLine;
             // Assert
             Assert.Equal(
                 "<input class=\"HtmlEncode[[text-box single-line]]\" id=\"HtmlEncode[[Property1]]\" name=\"HtmlEncode[[Property1]]\" type=\"HtmlEncode[[text]]\" value=\"HtmlEncode[[ViewData string]]\" />",
-                result.ToString());
+                HtmlContentUtilities.HtmlContentToString(result));
         }
 
         // DateTime-local is not special-cased unless using Html5DateRenderingMode.Rfc3339.
@@ -631,7 +632,7 @@ Environment.NewLine;
             var result = helper.Editor("");
 
             // Assert
-            Assert.Equal(expectedInput, result.ToString());
+            Assert.Equal(expectedInput, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -686,7 +687,7 @@ Environment.NewLine;
             var result = helper.Editor("");
 
             // Assert
-            Assert.Equal(expectedInput, result.ToString());
+            Assert.Equal(expectedInput, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -746,7 +747,7 @@ Environment.NewLine;
             var result = helper.Editor("");
 
             // Assert
-            Assert.Equal(expectedInput, result.ToString());
+            Assert.Equal(expectedInput, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -767,7 +768,7 @@ Environment.NewLine;
             // Assert
             Assert.Equal(
                 "<input class=\"HtmlEncode[[text-box single-line]]\" id=\"HtmlEncode[[Property1]]\" name=\"HtmlEncode[[Property1]]\" type=\"HtmlEncode[[text]]\" value=\"HtmlEncode[[Model string]]\" />",
-                result.ToString());
+                HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -787,7 +788,7 @@ Environment.NewLine;
             // Assert
             Assert.Equal(
                 "<input class=\"HtmlEncode[[text-box single-line]]\" id=\"HtmlEncode[[Property1]]\" name=\"HtmlEncode[[Property1]]\" type=\"HtmlEncode[[text]]\" value=\"HtmlEncode[[Model string]]\" />",
-                result.ToString());
+                HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -810,7 +811,7 @@ Environment.NewLine;
             // Assert
             Assert.Equal(
                 "<input class=\"HtmlEncode[[text-box single-line]]\" id=\"HtmlEncode[[Property1]]\" name=\"HtmlEncode[[Property1]]\" type=\"HtmlEncode[[text]]\" value=\"\" />",
-                result.ToString());
+                HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -917,11 +918,6 @@ Environment.NewLine;
                 get { return _innerHelper.TempData; }
             }
 
-            public IHtmlEncoder HtmlEncoder
-            {
-                get { return _innerHelper.HtmlEncoder; }
-            }
-
             public IUrlEncoder UrlEncoder
             {
                 get { return _innerHelper.UrlEncoder; }
@@ -937,7 +933,7 @@ Environment.NewLine;
                 (_innerHelper as ICanHasViewContext)?.Contextualize(viewContext);
             }
 
-            public HtmlString ActionLink(
+            public IHtmlContent ActionLink(
                 [NotNull] string linkText,
                 string actionName,
                 string controllerName,
@@ -950,7 +946,7 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            public HtmlString AntiForgeryToken()
+            public IHtmlContent AntiForgeryToken()
             {
                 throw new NotImplementedException();
             }
@@ -974,12 +970,12 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            public HtmlString CheckBox(string name, bool? isChecked, object htmlAttributes)
+            public IHtmlContent CheckBox(string name, bool? isChecked, object htmlAttributes)
             {
                 return HelperName("__CheckBox__", htmlAttributes);
             }
 
-            public HtmlString Display(
+            public IHtmlContent Display(
                 string expression,
                 string templateName,
                 string htmlFieldName,
@@ -998,7 +994,7 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            public HtmlString DropDownList(
+            public IHtmlContent DropDownList(
                 string name,
                 IEnumerable<SelectListItem> selectList,
                 string optionLabel,
@@ -1007,7 +1003,7 @@ Environment.NewLine;
                 return HelperName("__DropDownList__", htmlAttributes);
             }
 
-            public HtmlString Editor(
+            public IHtmlContent Editor(
                 string expression,
                 string templateName,
                 string htmlFieldName,
@@ -1058,7 +1054,7 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            public HtmlString Hidden(string name, object value, object htmlAttributes)
+            public IHtmlContent Hidden(string name, object value, object htmlAttributes)
             {
                 return HelperName("__Hidden__", htmlAttributes);
             }
@@ -1068,12 +1064,12 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            public HtmlString Label(string expression, string labelText, object htmlAttributes)
+            public IHtmlContent Label(string expression, string labelText, object htmlAttributes)
             {
                 return HelperName("__Label__", htmlAttributes);
             }
 
-            public HtmlString ListBox(string name, IEnumerable<SelectListItem> selectList, object htmlAttributes)
+            public IHtmlContent ListBox(string name, IEnumerable<SelectListItem> selectList, object htmlAttributes)
             {
                 throw new NotImplementedException();
             }
@@ -1091,22 +1087,22 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            public HtmlString Password(string name, object value, object htmlAttributes)
+            public IHtmlContent Password(string name, object value, object htmlAttributes)
             {
                 return HelperName("__Password__", htmlAttributes);
             }
 
-            public HtmlString RadioButton(string name, object value, bool? isChecked, object htmlAttributes)
+            public IHtmlContent RadioButton(string name, object value, bool? isChecked, object htmlAttributes)
             {
                 return HelperName("__RadioButton__", htmlAttributes);
             }
 
-            public HtmlString Raw(object value)
+            public IHtmlContent Raw(object value)
             {
                 throw new NotImplementedException();
             }
 
-            public HtmlString Raw(string value)
+            public IHtmlContent Raw(string value)
             {
                 throw new NotImplementedException();
             }
@@ -1116,7 +1112,7 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            public HtmlString RouteLink(
+            public IHtmlContent RouteLink(
                 [NotNull] string linkText,
                 string routeName,
                 string protocol,
@@ -1128,22 +1124,22 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            public HtmlString TextArea(string name, string value, int rows, int columns, object htmlAttributes)
+            public IHtmlContent TextArea(string name, string value, int rows, int columns, object htmlAttributes)
             {
                 return HelperName("__TextArea__", htmlAttributes);
             }
 
-            public HtmlString TextBox(string name, object value, string format, object htmlAttributes)
+            public IHtmlContent TextBox(string name, object value, string format, object htmlAttributes)
             {
                 return HelperName("__TextBox__", htmlAttributes);
             }
 
-            public HtmlString ValidationMessage(string modelName, string message, object htmlAttributes, string tag)
+            public IHtmlContent ValidationMessage(string modelName, string message, object htmlAttributes, string tag)
             {
                 return HelperName("__ValidationMessage__", htmlAttributes);
             }
 
-            public HtmlString ValidationSummary(
+            public IHtmlContent ValidationSummary(
                 bool excludePropertyErrors,
                 string message,
                 object htmlAttributes,
@@ -1157,7 +1153,7 @@ Environment.NewLine;
                 throw new NotImplementedException();
             }
 
-            private HtmlString HelperName(string name, object htmlAttributes)
+            private IHtmlContent HelperName(string name, object htmlAttributes)
             {
                 var htmlAttributesDictionary = HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);
                 var htmlAttributesString =

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperCheckboxTest.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.Globalization;
 using Microsoft.AspNet.Mvc.ModelBinding;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Routing;
 using Xunit;
 
@@ -31,7 +32,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                                        htmlAttributes: new { @checked = "checked", value = "false" });
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -53,7 +54,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                                        htmlAttributes: new { @checked = "unchecked", value = "false" });
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -70,7 +71,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                                        htmlAttributes: new { @checked = "unchecked", value = "false" });
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -121,7 +122,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: true, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -141,7 +142,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -160,7 +161,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -182,7 +183,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -203,7 +204,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Prefix.Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -225,7 +226,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -245,7 +246,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -266,7 +267,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -285,7 +286,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -305,7 +306,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -323,7 +324,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Name", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -344,7 +345,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: true, htmlAttributes: htmlAttributes);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -362,7 +363,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: false, htmlAttributes: dictionary);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -382,7 +383,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("Property1", isChecked: false, htmlAttributes: dictionary);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -403,7 +404,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox(string.Empty, isChecked: false, htmlAttributes: attributes);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -423,7 +424,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBox("ComplexProperty.Property1", isChecked: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -444,7 +445,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Theory]
@@ -472,7 +473,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -491,7 +492,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.Property3, new { @checked = "checked", value = "false" });
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -514,7 +515,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.Name, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Theory]
@@ -540,7 +541,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -560,7 +561,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.Property1, htmlAttributes);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -580,7 +581,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.Property1, attributes);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -601,7 +602,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.Property1, attributes);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -620,7 +621,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.CheckBoxFor(m => m.ComplexProperty.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         private static ViewDataDictionary<TestModel> GetTestModelViewData()

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperFormExtensionsTest.cs

@@ -276,7 +276,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         public void BeginFormWithNoParameters_CallsHtmlGeneratorWithExpectedValues()
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -310,7 +310,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         public void BeginFormWithMethodParameter_CallsHtmlGeneratorWithExpectedValues(FormMethod method)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -346,7 +346,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             object htmlAttributes)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -380,7 +380,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         public void BeginFormWithRouteValuesParameter_CallsHtmlGeneratorWithExpectedValues(object routeValues)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -416,7 +416,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             string controllerName)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -453,7 +453,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             object routeValues)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -490,7 +490,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             FormMethod method)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -528,7 +528,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             FormMethod method)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -566,7 +566,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             object htmlAttributes)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -600,7 +600,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         public void BeginRouteFormWithRouteValuesParameter_CallsHtmlGeneratorWithExpectedValues(object routeValues)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -633,7 +633,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         public void BeginRouteFormWithRouteNameParameter_CallsHtmlGeneratorWithExpectedValues(string routeName)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -668,7 +668,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             object routeValues)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -703,7 +703,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             FormMethod method)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -739,7 +739,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             FormMethod method)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator
@@ -775,7 +775,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             object htmlAttributes)
         {
             // Arrange
-            var tagBuilder = new TagBuilder(tagName: "form", htmlEncoder: new NullTestEncoder());
+            var tagBuilder = new TagBuilder(tagName: "form");
             var htmlGenerator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             var htmlHelper = DefaultTemplatesUtilities.GetHtmlHelper(htmlGenerator.Object);
             htmlGenerator

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperHiddenTest.cs

@@ -7,6 +7,7 @@ using System.ComponentModel.DataAnnotations;
 using System.Globalization;
 using System.Linq.Expressions;
 using Microsoft.AspNet.Mvc.ModelBinding;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Testing;
 using Xunit;
 
@@ -41,7 +42,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("ProductName", new byte[] { 23, 43, 53 }, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -56,7 +57,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", "test", attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -73,7 +74,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.Hidden("Prefix.Property1", value: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -91,7 +92,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.Hidden("Property1", value: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -108,7 +109,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.Hidden("Property1", value: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -126,7 +127,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.Hidden("Property1", value: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -142,7 +143,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", "explicit-value", attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -158,7 +159,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", "test", attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -174,7 +175,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", "test", attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -189,7 +190,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", value: "explicit-value", htmlAttributes: new { value = "attribute-value" });
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -205,7 +206,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", value: "explicit-value", htmlAttributes: new { value = "attribute-value" });
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -221,7 +222,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", value: null, htmlAttributes: new { value = "attribute-value" });
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -236,7 +237,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", value: null, htmlAttributes: new { value = "attribute-value" });
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -253,7 +254,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.Hidden("Property1", value: null, htmlAttributes: new { value = "attribute-value" });
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -267,7 +268,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", value: null, htmlAttributes: new { value = "attribute-value" });
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -283,7 +284,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.Hidden("Property1", value: null, htmlAttributes: new { value = "attribute-value" });
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -299,7 +300,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("keyNotFound", value: null, htmlAttributes: attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -315,7 +316,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.Hidden("keyNotFound", value: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, html.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -331,7 +332,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", "PropValue", htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -346,7 +347,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden(string.Empty, "fooValue", htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -368,7 +369,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", "explicit-value", htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -391,7 +392,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", value: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -432,7 +433,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property1", value: null, htmlAttributes: attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -449,7 +450,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden("Property2", value: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         public static IEnumerable<object[]> HiddenWithComplexExpressions_UsesValueFromViewDataData
@@ -495,7 +496,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden(expression, value: null, htmlAttributes: attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         public static IEnumerable<object[]> HiddenWithComplexExpressions_UsesIdDotSeparatorData
@@ -534,7 +535,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Hidden(expression, value: null, htmlAttributes: attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -549,7 +550,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Bytes, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -564,7 +565,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, htmlAttributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -579,7 +580,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -595,7 +596,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -611,7 +612,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -626,7 +627,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         // This test ensures that specifying a the prefix does not affect the expression result.
@@ -644,7 +645,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -667,7 +668,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -687,7 +688,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -704,7 +705,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property2, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         public static TheoryData HiddenFor_UsesPropertyValueIfModelStateDoesNotContainValueData
@@ -765,7 +766,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(expression, attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         public static TheoryData HiddenFor_UsesModelStateValueForComplexExpressionsData
@@ -813,7 +814,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(expression, attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -831,7 +832,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.HiddenFor(m => m.Property1, attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         private static ViewDataDictionary<HiddenModel> GetViewDataWithNullModelAndNonNullViewData()

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperLabelExtensionsTest.cs

@@ -4,6 +4,7 @@
 using System;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Xunit;
 
 namespace Microsoft.AspNet.Mvc.Core
@@ -26,10 +27,10 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelForModelResult = helper.LabelForModel();
 
             // Assert
-            Assert.Empty(labelResult.ToString());
-            Assert.Empty(labelNullResult.ToString());
-            Assert.Empty(labelForResult.ToString());
-            Assert.Empty(labelForModelResult.ToString());
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelNullResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelForResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelForModelResult));
         }
 
         [Fact]
@@ -43,8 +44,8 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelForResult = helper.LabelFor(m => m.Property1);
 
             // Assert
-            Assert.Equal("<label for=\"HtmlEncode[[Property1]]\">HtmlEncode[[Property1]]</label>", labelResult.ToString());
-            Assert.Equal("<label for=\"HtmlEncode[[Property1]]\">HtmlEncode[[Property1]]</label>", labelForResult.ToString());
+            Assert.Equal("<label for=\"HtmlEncode[[Property1]]\">HtmlEncode[[Property1]]</label>", HtmlContentUtilities.HtmlContentToString(labelResult));
+            Assert.Equal("<label for=\"HtmlEncode[[Property1]]\">HtmlEncode[[Property1]]</label>", HtmlContentUtilities.HtmlContentToString(labelForResult));
         }
 
         [Fact]
@@ -58,8 +59,8 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelForResult = helper.LabelFor(m => m.Inner.Id);
 
             // Assert
-            Assert.Equal("<label for=\"HtmlEncode[[Inner_Id]]\">HtmlEncode[[Id]]</label>", labelResult.ToString());
-            Assert.Equal("<label for=\"HtmlEncode[[Inner_Id]]\">HtmlEncode[[Id]]</label>", labelForResult.ToString());
+            Assert.Equal("<label for=\"HtmlEncode[[Inner_Id]]\">HtmlEncode[[Id]]</label>", HtmlContentUtilities.HtmlContentToString(labelResult));
+            Assert.Equal("<label for=\"HtmlEncode[[Inner_Id]]\">HtmlEncode[[Id]]</label>", HtmlContentUtilities.HtmlContentToString(labelForResult));
         }
 
         [Fact]
@@ -83,9 +84,9 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelForModelResult = helper.LabelForModel();
 
             // Assert
-            Assert.Equal("<label for=\"\">HtmlEncode[[" + propertyName + "]]</label>", labelResult.ToString());
-            Assert.Equal("<label for=\"\">HtmlEncode[[" + propertyName + "]]</label>", labelForResult.ToString());
-            Assert.Equal("<label for=\"\">HtmlEncode[[" + propertyName + "]]</label>", labelForModelResult.ToString());
+            Assert.Equal("<label for=\"\">HtmlEncode[[" + propertyName + "]]</label>", HtmlContentUtilities.HtmlContentToString(labelResult));
+            Assert.Equal("<label for=\"\">HtmlEncode[[" + propertyName + "]]</label>", HtmlContentUtilities.HtmlContentToString(labelForResult));
+            Assert.Equal("<label for=\"\">HtmlEncode[[" + propertyName + "]]</label>", HtmlContentUtilities.HtmlContentToString(labelForModelResult));
         }
 
         // If the metadata is for a type (not property), then Label(expression) will evaluate the expression
@@ -100,7 +101,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelResult = helper.Label(expression: "value");
 
             // Assert
-            Assert.Equal("<label for=\"HtmlEncode[[value]]\">HtmlEncode[[value]]</label>", labelResult.ToString());
+            Assert.Equal("<label for=\"HtmlEncode[[value]]\">HtmlEncode[[value]]</label>", HtmlContentUtilities.HtmlContentToString(labelResult));
         }
 
         [Fact]
@@ -121,10 +122,10 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelForModelResult = helper.LabelForModel();
 
             // Assert
-            Assert.Empty(labelResult.ToString());
-            Assert.Empty(labelNullResult.ToString());
-            Assert.Empty(labelForResult.ToString());
-            Assert.Empty(labelForModelResult.ToString());
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelNullResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelForResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelForModelResult));
         }
 
         [Theory]
@@ -146,9 +147,9 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelForModelResult = helper.LabelForModel();
 
             // Assert
-            Assert.Equal("<label for=\"\">HtmlEncode[[" + displayName + "]]</label>", labelResult.ToString());
-            Assert.Equal("<label for=\"\">HtmlEncode[[" + displayName + "]]</label>", labelForResult.ToString());
-            Assert.Equal("<label for=\"\">HtmlEncode[[" + displayName + "]]</label>", labelForModelResult.ToString());
+            Assert.Equal("<label for=\"\">HtmlEncode[[" + displayName + "]]</label>", HtmlContentUtilities.HtmlContentToString(labelResult));
+            Assert.Equal("<label for=\"\">HtmlEncode[[" + displayName + "]]</label>", HtmlContentUtilities.HtmlContentToString(labelForResult));
+            Assert.Equal("<label for=\"\">HtmlEncode[[" + displayName + "]]</label>", HtmlContentUtilities.HtmlContentToString(labelForModelResult));
         }
 
         [Fact]
@@ -173,10 +174,10 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelForModelResult = helper.LabelForModel();
 
             // Assert
-            Assert.Empty(labelResult.ToString());
-            Assert.Empty(labelNullResult.ToString());
-            Assert.Empty(labelForResult.ToString());
-            Assert.Empty(labelForModelResult.ToString());
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelNullResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelForResult));
+            Assert.Empty(HtmlContentUtilities.HtmlContentToString(labelForModelResult));
         }
 
         [Theory]
@@ -197,8 +198,8 @@ namespace Microsoft.AspNet.Mvc.Core
             var labelForResult = helper.LabelFor(m => m.Property1);
 
             // Assert
-            Assert.Equal("<label for=\"HtmlEncode[[Property1]]\">HtmlEncode[[" + displayName + "]]</label>", labelResult.ToString());
-            Assert.Equal("<label for=\"HtmlEncode[[Property1]]\">HtmlEncode[[" + displayName + "]]</label>", labelForResult.ToString());
+            Assert.Equal("<label for=\"HtmlEncode[[Property1]]\">HtmlEncode[[" + displayName + "]]</label>", HtmlContentUtilities.HtmlContentToString(labelResult));
+            Assert.Equal("<label for=\"HtmlEncode[[Property1]]\">HtmlEncode[[" + displayName + "]]</label>", HtmlContentUtilities.HtmlContentToString(labelForResult));
         }
 
         [Theory]
@@ -219,7 +220,7 @@ namespace Microsoft.AspNet.Mvc.Core
 
             // Assert
             // Label() falls back to expression name when DisplayName and PropertyName are null.
-            Assert.Equal("<label for=\"HtmlEncode[[" + expectedId + "]]\">HtmlEncode[[" + expectedText + "]]</label>", result.ToString());
+            Assert.Equal("<label for=\"HtmlEncode[[" + expectedId + "]]\">HtmlEncode[[" + expectedText + "]]</label>", HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -247,7 +248,7 @@ namespace Microsoft.AspNet.Mvc.Core
             var result = helper.LabelFor(model => unknownKey);
 
             // Assert
-            Assert.Equal("<label for=\"HtmlEncode[[unknownKey]]\">HtmlEncode[[unknownKey]]</label>", result.ToString());
+            Assert.Equal("<label for=\"HtmlEncode[[unknownKey]]\">HtmlEncode[[unknownKey]]</label>", HtmlContentUtilities.HtmlContentToString(result));
         }
 
         private sealed class InnerClass

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperLinkGenerationTest.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Generic;
 using System.Linq;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.Framework.Internal;
 using Moq;
 using Xunit;
@@ -78,10 +79,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                                             hostname: hostname,
                                             fragment: fragment,
                                             routeValues: routeValues,
-                                            htmlAttributes: htmlAttributes).ToString();
+                                            htmlAttributes: htmlAttributes);
 
             // Assert
-            Assert.Equal(expectedLink, actualLink);
+            Assert.Equal(expectedLink, HtmlContentUtilities.HtmlContentToString(actualLink));
         }
 
         public static IEnumerable<object[]> RouteLinkGenerationData
@@ -141,10 +142,10 @@ namespace Microsoft.AspNet.Mvc.Rendering
                                             hostName: hostname,
                                             fragment: fragment,
                                             routeValues: routeValues,
-                                            htmlAttributes: htmlAttributes).ToString();
+                                            htmlAttributes: htmlAttributes);
 
             // Assert
-            Assert.Equal(expectedLink, actualLink);
+            Assert.Equal(expectedLink, HtmlContentUtilities.HtmlContentToString(actualLink));
         }
 
         private string GetRouteValuesAsString(object routeValues)

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperPasswordTest.cs

@@ -7,6 +7,7 @@ using System.ComponentModel.DataAnnotations;
 using System.Globalization;
 using System.Linq.Expressions;
 using Microsoft.AspNet.Mvc.ModelBinding;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Testing;
 using Xunit;
 
@@ -51,7 +52,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Password("Property1", value: null, htmlAttributes: attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -68,7 +69,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Password("Property1", "explicit-value", attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -84,7 +85,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Password("Property1", "explicit-value", htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -102,7 +103,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Password("Property1", "explicit-value", htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -118,7 +119,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Password(name, "explicit-value", htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -159,7 +160,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Password("Property1", value: null, htmlAttributes: attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -176,7 +177,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Password("Property2", value: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         public static IEnumerable<object[]> PasswordWithComplexExpressions_UsesIdDotSeparatorData
@@ -212,7 +213,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.Password(expression, value: null, htmlAttributes: attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -230,7 +231,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.PasswordFor(m => m.Property1, htmlAttributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -245,7 +246,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.PasswordFor(m => m.Property1, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -267,7 +268,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.PasswordFor(m => m.Property1, attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -284,7 +285,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.PasswordFor(m => m.Property2, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         public static TheoryData PasswordFor_WithComplexExpressionsData
@@ -338,7 +339,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var result = helper.PasswordFor(expression, attributes);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         private static ViewDataDictionary<PasswordModel> GetViewDataWithNullModelAndNonEmptyViewData()

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperSelectTest.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using Microsoft.AspNet.Mvc.ModelBinding;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Testing;
 using Microsoft.Framework.Internal;
 using Microsoft.Framework.WebEncoders;
@@ -334,7 +335,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", selectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedDisabled, selectList.Select(item => item.Disabled));
             Assert.Equal(savedGroup, selectList.Select(item => item.Group));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
@@ -358,7 +359,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", selectList: null, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -399,7 +400,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", selectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -439,7 +440,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", SourcesSelectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -481,7 +482,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", SourcesSelectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -506,7 +507,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", SourcesSelectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -534,7 +535,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", SourcesSelectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -561,7 +562,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", SourcesSelectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -577,7 +578,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", SourcesSelectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -594,7 +595,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownList("Property1", SourcesSelectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Theory]
@@ -616,7 +617,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -640,7 +641,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -664,7 +665,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -689,7 +690,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -717,7 +718,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -740,7 +741,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownListFor(value => unrelated, selectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -764,7 +765,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedDisabled, selectList.Select(item => item.Disabled));
             Assert.Equal(savedGroup, selectList.Select(item => item.Group));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
@@ -789,7 +790,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -810,7 +811,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -850,7 +851,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", SourcesSelectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -892,7 +893,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", SourcesSelectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -917,7 +918,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", SourcesSelectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -945,7 +946,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", SourcesSelectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -972,7 +973,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", SourcesSelectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -988,7 +989,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", SourcesSelectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Fact]
@@ -1005,7 +1006,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox("Property1", SourcesSelectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
         }
 
         [Theory]
@@ -1024,7 +1025,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBoxFor(value => value.Property1, selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1045,7 +1046,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBoxFor(value => value.Property1, selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1069,7 +1070,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBoxFor(value => unrelated, selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1090,7 +1091,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBoxFor(value => value.Property1, selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1118,7 +1119,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedDisabled, selectList.Select(item => item.Disabled));
             Assert.Equal(savedGroup, selectList.Select(item => item.Group));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
@@ -1146,7 +1147,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1166,7 +1167,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownListFor(value => value, selectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1186,7 +1187,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.DropDownListFor(value => value, selectList, optionLabel: null, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1211,7 +1212,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox(expression: string.Empty, selectList: selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedDisabled, selectList.Select(item => item.Disabled));
             Assert.Equal(savedGroup, selectList.Select(item => item.Group));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
@@ -1237,7 +1238,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBox(expression: string.Empty, selectList: selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1258,7 +1259,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBoxFor(value => value, selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 
@@ -1280,7 +1281,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var html = helper.ListBoxFor(value => value, selectList, htmlAttributes: null);
 
             // Assert
-            Assert.Equal(expectedHtml, html.ToString());
+            Assert.Equal(expectedHtml, HtmlContentUtilities.HtmlContentToString(html));
             Assert.Equal(savedSelected, selectList.Select(item => item.Selected));
         }
 

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/HtmlHelperValidationSummaryTest.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using Microsoft.AspNet.Mvc.ModelBinding;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Xunit;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -150,7 +151,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 tag: tag);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -222,7 +223,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 tag: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -248,7 +249,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 tag: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -273,7 +274,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 tag: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Theory]
@@ -297,7 +298,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 tag: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         [Fact]
@@ -330,7 +331,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 tag: null);
 
             // Assert
-            Assert.Equal(expected, result.ToString());
+            Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(result));
         }
 
         // Adds errors for various parts of the model, including the root.

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/StringCollectionTextWriterTest.cs

@@ -7,6 +7,7 @@ using System.IO;
 using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Testing;
+using Microsoft.Framework.Internal;
 using Microsoft.Framework.WebEncoders.Testing;
 using Xunit;
 

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/StringHtmlContentTest.cs

@@ -0,0 +1,46 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.IO;
+using Microsoft.Framework.WebEncoders.Testing;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.Rendering
+{
+    public class StringHtmlContentTest
+    {
+        [Fact]
+        public void ToString_ReturnsAString()
+        {
+            // Arrange & Act
+            var content = new StringHtmlContent("Hello World");
+
+            // Assert
+            Assert.Equal("Hello World", content.ToString());
+        }
+
+        [Fact]
+        public void ToString_ReturnsNullForNullInput()
+        {
+            // Arrange & Act
+            var content = new StringHtmlContent(null);
+
+            // Assert
+            Assert.Null(content.ToString());
+        }
+
+        [Fact]
+        public void WriteTo_WritesContent()
+        {
+            // Arrange & Act
+            var content = new StringHtmlContent("Hello World");
+
+            // Assert
+            using (var writer = new StringWriter())
+            {
+                content.WriteTo(writer, new CommonTestEncoder());
+                Assert.Equal("HtmlEncode[[Hello World]]", writer.ToString());
+            }
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/TagBuilderTest.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Generic;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.Framework.WebEncoders.Testing;
 using Xunit;
 
@@ -29,7 +30,7 @@ namespace Microsoft.AspNet.Mvc.Core.Rendering
         public void MergeAttribute_IgnoresCase(bool replaceExisting, string expectedKey, string expectedValue)
         {
             // Arrange
-            var tagBuilder = new TagBuilder("p", new NullTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             tagBuilder.Attributes.Add("Hello", "World");
 
             // Act
@@ -44,7 +45,7 @@ namespace Microsoft.AspNet.Mvc.Core.Rendering
         public void AddCssClass_IgnoresCase()
         {
             // Arrange
-            var tagBuilder = new TagBuilder("p", new NullTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             tagBuilder.Attributes.Add("ClaSs", "btn");
 
             // Act
@@ -59,7 +60,7 @@ namespace Microsoft.AspNet.Mvc.Core.Rendering
         public void GenerateId_IgnoresCase()
         {
             // Arrange
-            var tagBuilder = new TagBuilder("p", new NullTestEncoder());
+            var tagBuilder = new TagBuilder("p");
             tagBuilder.Attributes.Add("ID", "something");
 
             // Act
@@ -75,16 +76,16 @@ namespace Microsoft.AspNet.Mvc.Core.Rendering
         public void ToString_IgnoresIdAttributeCase(TagRenderMode renderingMode, string expectedOutput)
         {
             // Arrange
-            var tagBuilder = new TagBuilder("p", new NullTestEncoder());
+            var tagBuilder = new TagBuilder("p");
 
             // An empty value id attribute should not be rendered via ToString.
             tagBuilder.Attributes.Add("ID", string.Empty);
 
             // Act
-            var value = tagBuilder.ToString(renderingMode);
+            var value = tagBuilder.ToHtmlContent(renderingMode);
 
             // Assert
-            Assert.Equal(expectedOutput, value);
+            Assert.Equal(expectedOutput, HtmlContentUtilities.HtmlContentToString(value, new NullTestEncoder()));
         }
 
         [Theory]
@@ -92,29 +93,31 @@ namespace Microsoft.AspNet.Mvc.Core.Rendering
         public void ToHtmlString_IgnoresIdAttributeCase(TagRenderMode renderingMode, string expectedOutput)
         {
             // Arrange
-            var tagBuilder = new TagBuilder("p", new NullTestEncoder());
+            var tagBuilder = new TagBuilder("p");
 
             // An empty value id attribute should not be rendered via ToHtmlString.
             tagBuilder.Attributes.Add("ID", string.Empty);
 
             // Act
-            var value = tagBuilder.ToHtmlString(renderingMode);
+            var value = tagBuilder.ToHtmlContent(renderingMode);
 
             // Assert
-            Assert.Equal(expectedOutput, value.ToString());
+            Assert.Equal(expectedOutput, HtmlContentUtilities.HtmlContentToString(value, new NullTestEncoder()));
         }
 
         [Fact]
         public void SetInnerText_HtmlEncodesValue()
         {
             // Arrange
-            var tagBuilder = new TagBuilder("p", new CommonTestEncoder());
+            var tagBuilder = new TagBuilder("p");
 
             // Act
             tagBuilder.SetInnerText("TestValue");
 
             // Assert
-            Assert.Equal("HtmlEncode[[TestValue]]", tagBuilder.InnerHtml);
+            Assert.Equal(
+                "HtmlEncode[[TestValue]]",
+                HtmlContentUtilities.HtmlContentToString(tagBuilder.InnerHtml));
         }
 
         [Theory]

test/WebSites/ActivatorWebSite/TagHelpers/TitleTagHelper.cs

@@ -25,10 +25,10 @@ namespace ActivatorWebSite.TagHelpers
         {
             (HtmlHelper as ICanHasViewContext)?.Contextualize(ViewContext);
 
-            var builder = new TagBuilder("h2", HtmlHelper.HtmlEncoder);
+            var builder = new TagBuilder("h2");
             var title = ViewContext.ViewBag.Title;
-            builder.InnerHtml = HtmlHelper.Encode(title);
-            output.PreContent.SetContent(builder.ToString());
+            builder.SetInnerText(title);
+            output.PreContent.SetContent(builder.ToHtmlContent(TagRenderMode.Normal));
         }
     }
 }