Making TagBuilder implement IHtmlContent and removing ToHtmlContent.

- Making TagRenderMode a property in TagBuilder.
- Modifying places where TagBuilder is used to suit the new model.
- This reduces space occupied by a normal application by 11.8%.

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

@@ -163,7 +163,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 var antiforgeryTag = Generator.GenerateAntiforgery(ViewContext);
                 if (antiforgeryTag != null)
                 {
-                    output.PostContent.Append(antiforgeryTag.ToString());
+                    output.PostContent.Append(antiforgeryTag);
                 }
             }
         }

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

@@ -236,13 +236,13 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 }
             }
 
-            var tagBuilder = Generator.GenerateCheckBox(
+            var checkBoxTag = Generator.GenerateCheckBox(
                 ViewContext,
                 modelExplorer,
                 For.Name,
                 isChecked: null,
                 htmlAttributes: htmlAttributes);
-            if (tagBuilder != null)
+            if (checkBoxTag != null)
             {
                 // Do not generate current element's attributes or tags. Instead put both <input type="checkbox"/> and
                 // <input type="hidden"/> into the output's Content.
@@ -251,12 +251,14 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
 
                 var renderingMode =
                     output.TagMode == TagMode.SelfClosing ? TagRenderMode.SelfClosing : TagRenderMode.StartTag;
-                output.Content.Append(tagBuilder.ToHtmlContent(renderingMode));
+                checkBoxTag.TagRenderMode = renderingMode;
+                output.Content.Append(checkBoxTag);
 
-                tagBuilder = Generator.GenerateHiddenForCheckbox(ViewContext, modelExplorer, For.Name);
+                var hiddenForCheckboxTag = Generator.GenerateHiddenForCheckbox(ViewContext, modelExplorer, For.Name);
-                if (tagBuilder != null)
+                if (hiddenForCheckboxTag != null)
                 {
-                    output.Content.Append(tagBuilder.ToHtmlContent(renderingMode));
+                    hiddenForCheckboxTag.TagRenderMode = renderingMode;
+                    output.Content.Append(hiddenForCheckboxTag);
                 }
             }
         }

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

@@ -41,7 +41,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 inputTag.Attributes["checked"] = "checked";
             }
 
-            return inputTag.ToHtmlContent(TagRenderMode.SelfClosing);
+            inputTag.TagRenderMode = TagRenderMode.SelfClosing;
+            return inputTag;
         }
 
         private static IHtmlContent BooleanTemplateDropDownList(IHtmlHelper htmlHelper, bool? value)
@@ -52,17 +53,13 @@ namespace Microsoft.AspNet.Mvc.Rendering
             selectTag.Attributes["disabled"] = "disabled";
 
             var content = new BufferedHtmlContent();
-            content.Append(selectTag.ToHtmlContent(TagRenderMode.StartTag));
-
             foreach (var item in TriStateValues(value))
             {
-                content.Append(
+                content.Append(DefaultHtmlGenerator.GenerateOption(item, item.Text));
-                    DefaultHtmlGenerator.GenerateOption(item, item.Text)
-                        .ToHtmlContent(TagRenderMode.Normal));
             }
 
-            content.Append(selectTag.ToHtmlContent(TagRenderMode.EndTag));
+            selectTag.InnerHtml = content;
-            return content;
+            return selectTag;
         }
 
         // Will soon need to be shared with the default editor templates implementations.
@@ -208,7 +205,6 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var viewData = htmlHelper.ViewData;
             var templateInfo = viewData.TemplateInfo;
             var modelExplorer = viewData.ModelExplorer;
-            var content = new BufferedHtmlContent();
 
             if (modelExplorer.Model == null)
             {
@@ -229,6 +225,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             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;
@@ -237,25 +234,6 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     continue;
                 }
 
-                var divTag = new TagBuilder("div");
-
-                if (!propertyMetadata.HideSurroundingHtml)
-                {
-                    var label = propertyMetadata.GetDisplayName();
-                    if (!string.IsNullOrEmpty(label))
-                    {
-                        divTag.SetInnerText(label);
-                        divTag.AddCssClass("display-label");
-                        content.AppendLine(divTag.ToHtmlContent(TagRenderMode.Normal));
-
-                        // Reset divTag for reuse.
-                        divTag.Attributes.Clear();
-                    }
-
-                    divTag.AddCssClass("display-field");
-                    content.Append(divTag.ToHtmlContent(TagRenderMode.StartTag));
-                }
-
                 var templateBuilder = new TemplateBuilder(
                     viewEngine,
                     htmlHelper.ViewContext,
@@ -266,11 +244,26 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     readOnly: true,
                     additionalViewData: null);
 
-                content.Append(templateBuilder.Build());
+                var templateBuilderResult = templateBuilder.Build();
-
                 if (!propertyMetadata.HideSurroundingHtml)
                 {
-                    content.AppendLine(divTag.ToHtmlContent(TagRenderMode.EndTag));
+                    var label = propertyMetadata.GetDisplayName();
+                    if (!string.IsNullOrEmpty(label))
+                    {
+                        var labelTag = new TagBuilder("div");
+                        labelTag.SetInnerText(label);
+                        labelTag.AddCssClass("display-label");
+                        content.AppendLine(labelTag);
+                    }
+
+                    var valueDivTag = new TagBuilder("div");
+                    valueDivTag.AddCssClass("display-field");
+                    valueDivTag.InnerHtml = templateBuilderResult;
+                    content.AppendLine(valueDivTag);
+                }
+                else
+                {
+                    content.Append(templateBuilderResult);
                 }
             }
 
@@ -312,8 +305,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var hyperlinkTag = new TagBuilder("a");
             hyperlinkTag.MergeAttribute("href", uriString);
             hyperlinkTag.SetInnerText(linkedText);
-
+            return hyperlinkTag;
-            return hyperlinkTag.ToHtmlContent(TagRenderMode.Normal);
         }
     }
 }

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

@@ -256,28 +256,6 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     continue;
                 }
 
-                var divTag = new TagBuilder("div");
-
-                if (!propertyMetadata.HideSurroundingHtml)
-                {
-                    var label = htmlHelper.Label(
-                        propertyMetadata.PropertyName,
-                        labelText: null,
-                        htmlAttributes: null);
-                    if (!string.IsNullOrEmpty(label.ToString()))
-                    {
-                        divTag.AddCssClass("editor-label");
-                        divTag.InnerHtml = label; // already escaped
-                        content.AppendLine(divTag.ToHtmlContent(TagRenderMode.Normal));
-
-                        // Reset divTag for reuse.
-                        divTag.Attributes.Clear();
-                    }
-
-                    divTag.AddCssClass("editor-field");
-                    content.Append(divTag.ToHtmlContent(TagRenderMode.StartTag));
-                }
-
                 var templateBuilder = new TemplateBuilder(
                     viewEngine,
                     htmlHelper.ViewContext,
@@ -288,18 +266,36 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     readOnly: false,
                     additionalViewData: null);
 
-                content.Append(templateBuilder.Build());
+                var templateBuilderResult = templateBuilder.Build();
-
                 if (!propertyMetadata.HideSurroundingHtml)
                 {
-                    content.Append(" ");
+                    var label = htmlHelper.Label(propertyMetadata.PropertyName, labelText: null, htmlAttributes: null);
-                    content.Append(htmlHelper.ValidationMessage(
+                    if (!string.IsNullOrEmpty(label.ToString()))
+                    {
+                        var labelTag = new TagBuilder("div");
+                        labelTag.AddCssClass("editor-label");
+                        labelTag.InnerHtml = label;
+                        content.AppendLine(labelTag);
+                    }
+
+                    var valueDivTag = new TagBuilder("div");
+                    valueDivTag.AddCssClass("editor-field");
+
+                    var innerContent = new BufferedHtmlContent();
+                    innerContent.Append(templateBuilderResult);
+                    innerContent.Append(" ");
+                    innerContent.Append(htmlHelper.ValidationMessage(
                         propertyMetadata.PropertyName,
                         message: null,
                         htmlAttributes: null,
                         tag: null));
+                    valueDivTag.InnerHtml = innerContent;
 
-                    content.AppendLine(divTag.ToHtmlContent(TagRenderMode.EndTag));
+                    content.AppendLine(valueDivTag);
+                }
+                else
+                {
+                    content.Append(templateBuilderResult);
                 }
             }
 

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

@@ -157,6 +157,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             var tagBuilder = new TagBuilder("input");
             tagBuilder.MergeAttribute("type", GetInputTypeString(InputType.Hidden));
             tagBuilder.MergeAttribute("value", "false");
+            tagBuilder.TagRenderMode = TagRenderMode.SelfClosing;
 
             var fullName = GetFullHtmlFieldName(viewContext, expression);
             tagBuilder.MergeAttribute("name", fullName);
@@ -673,7 +674,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 }
                 var messageTag = new TagBuilder(headerTag);
                 messageTag.SetInnerText(message);
-                wrappedMessage.AppendLine(messageTag.ToHtmlContent(TagRenderMode.Normal));
+                wrappedMessage.AppendLine(messageTag);
             }
             else
             {
@@ -696,7 +697,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     {
                         var listItem = new TagBuilder("li");
                         listItem.SetInnerText(errorText);
-                        htmlSummary.AppendLine(listItem.ToHtmlContent(TagRenderMode.Normal));
+                        htmlSummary.AppendLine(listItem);
                         isHtmlSummaryModified = true;
                     }
                 }
@@ -726,7 +727,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
             var innerContent = new BufferedHtmlContent();
             innerContent.Append(wrappedMessage);
-            innerContent.Append(unorderedList.ToHtmlContent(TagRenderMode.Normal));
+            innerContent.Append(unorderedList);
             tagBuilder.InnerHtml = innerContent;
 
             if (formContext != null && !excludePropertyErrors)
@@ -1015,6 +1016,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
 
             var tagBuilder = new TagBuilder("input");
+            tagBuilder.TagRenderMode = TagRenderMode.SelfClosing;
             tagBuilder.MergeAttributes(htmlAttributes);
             tagBuilder.MergeAttribute("type", GetInputTypeString(inputType));
             tagBuilder.MergeAttribute("name", fullName, replaceExisting: true);
@@ -1302,12 +1304,9 @@ namespace Microsoft.AspNet.Mvc.Rendering
             foreach (var group in groupedSelectList)
             {
                 var optGroup = group.First().Group;
-
-                // Wrap if requested.
-                TagBuilder groupBuilder = null;
                 if (optGroup != null)
                 {
-                    groupBuilder = new TagBuilder("optgroup");
+                    var groupBuilder = new TagBuilder("optgroup");
                     if (optGroup.Name != null)
                     {
                         groupBuilder.MergeAttribute("label", optGroup.Name);
@@ -1318,17 +1317,21 @@ namespace Microsoft.AspNet.Mvc.Rendering
                         groupBuilder.MergeAttribute("disabled", "disabled");
                     }
 
-                    listItemBuilder.AppendLine(groupBuilder.ToHtmlContent(TagRenderMode.StartTag));
+                    var optGroupContent = new BufferedHtmlContent().Append(Environment.NewLine);
-                }
+                    foreach (var item in group)
+                    {
+                        optGroupContent.AppendLine(GenerateOption(item));
+                    }
 
-                foreach (var item in group)
+                    groupBuilder.InnerHtml = optGroupContent;
-                {
+                    listItemBuilder.AppendLine(groupBuilder);
-                    listItemBuilder.AppendLine(GenerateOption(item));
                 }
-
+                else
-                if (optGroup != null)
                 {
-                    listItemBuilder.AppendLine(groupBuilder.ToHtmlContent(TagRenderMode.EndTag));
+                    foreach (var item in group)
+                    {
+                        listItemBuilder.AppendLine(GenerateOption(item));
+                    }
                 }
             }
 
@@ -1338,7 +1341,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
         private IHtmlContent GenerateOption(SelectListItem item)
         {
             var tagBuilder = GenerateOption(item, item.Text);
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
     }
 }

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

@@ -214,7 +214,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
 
         /// <inheritdoc />
@@ -542,7 +542,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
 
         /// <inheritdoc />
@@ -643,11 +643,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            var elements = new BufferedHtmlContent();
+            return new BufferedHtmlContent().Append(checkbox).Append(hidden);
-            elements.Append(checkbox.ToHtmlContent(TagRenderMode.SelfClosing));
-            elements.Append(hidden.ToHtmlContent(TagRenderMode.SelfClosing));
-
-            return elements;
         }
 
         protected virtual string GenerateDisplayName([NotNull] ModelExplorer modelExplorer, string expression)
@@ -690,7 +686,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
 
         protected virtual IHtmlContent GenerateEditor(
@@ -751,7 +747,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes);
             if (tagBuilder != null)
             {
-                tagBuilder.ToHtmlContent(TagRenderMode.StartTag).WriteTo(ViewContext.Writer, _htmlEncoder);
+                tagBuilder.TagRenderMode = TagRenderMode.StartTag;
+                tagBuilder.WriteTo(ViewContext.Writer, _htmlEncoder);
             }
 
             return CreateForm();
@@ -793,7 +790,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 htmlAttributes);
             if (tagBuilder != null)
             {
-                tagBuilder.ToHtmlContent(TagRenderMode.StartTag).WriteTo(ViewContext.Writer, _htmlEncoder);
+                tagBuilder.TagRenderMode = TagRenderMode.StartTag;
+                tagBuilder.WriteTo(ViewContext.Writer, _htmlEncoder);
             }
 
             return CreateForm();
@@ -819,7 +817,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
+            return tagBuilder;
         }
 
         protected virtual string GenerateId(string expression)
@@ -847,7 +845,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
 
         protected IHtmlContent GenerateListBox(
@@ -869,7 +867,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
 
         protected virtual string GenerateName(string expression)
@@ -895,7 +893,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
+            return tagBuilder;
         }
 
         protected virtual IHtmlContent GenerateRadioButton(
@@ -917,7 +915,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
+            return tagBuilder;
         }
 
         protected virtual IHtmlContent GenerateTextArea(
@@ -939,7 +937,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
 
         protected virtual IHtmlContent GenerateTextBox(
@@ -961,7 +959,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
+            return tagBuilder;
         }
 
         protected virtual IHtmlContent GenerateValidationMessage(
@@ -981,7 +979,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
 
         protected virtual IHtmlContent GenerateValidationSummary(
@@ -1001,7 +999,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 return HtmlString.Empty;
             }
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.Normal);
+            return tagBuilder;
         }
 
         protected virtual string GenerateValue(string expression, object value, string format, bool useViewData)

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

@@ -9,10 +9,11 @@ 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
+    public class TagBuilder : IHtmlContent
     {
         public TagBuilder(string tagName)
         {
@@ -31,6 +32,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
 
         public string TagName { get; private set; }
 
+        /// <summary>
+        /// The <see cref="Rendering.TagRenderMode"/> with which the tag is written.
+        /// </summary>
+        /// <remarks>Defaults to <see cref="TagRenderMode.Normal"/>.</remarks>
+        public TagRenderMode TagRenderMode { get; set; } = TagRenderMode.Normal;
+
         public void AddCssClass(string value)
         {
             string currentValue;
@@ -125,7 +132,7 @@ namespace Microsoft.AspNet.Mvc.Rendering
             }
         }
 
-        private void AppendAttributes(BufferedHtmlContent content)
+        private void AppendAttributes(TextWriter writer, IHtmlEncoder encoder)
         {
             foreach (var attribute in Attributes)
             {
@@ -136,11 +143,11 @@ namespace Microsoft.AspNet.Mvc.Rendering
                     continue;
                 }
 
-                content.Append(" ");
+                writer.Write(" ");
-                content.Append(key);
+                writer.Write(key);
-                content.Append("=\"");
+                writer.Write("=\"");
-                content.Append(new StringHtmlContent(attribute.Value));
+                encoder.HtmlEncode(attribute.Value, writer);
-                content.Append("\"");
+                writer.Write("\"");
             }
         }
 
@@ -185,48 +192,39 @@ namespace Microsoft.AspNet.Mvc.Rendering
             InnerHtml = new StringHtmlContent(innerText);
         }
 
-        /// <summary>
+        /// <inheritdoc />
-        /// Converts the <see cref="TagBuilder"/> to <see cref="IHtmlContent"/> with the specified
+        public void WriteTo(TextWriter writer, IHtmlEncoder encoder)
-        /// <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)
         {
-            var content = new BufferedHtmlContent();
+            switch (TagRenderMode)
-            switch (renderMode)
             {
                 case TagRenderMode.StartTag:
-                    content.Append("<");
+                    writer.Write("<");
-                    content.Append(TagName);
+                    writer.Write(TagName);
-                    AppendAttributes(content);
+                    AppendAttributes(writer, encoder);
-                    content.Append(">");
+                    writer.Write(">");
                     break;
                 case TagRenderMode.EndTag:
-                    content.Append("</");
+                    writer.Write("</");
-                    content.Append(TagName);
+                    writer.Write(TagName);
-                    content.Append(">");
+                    writer.Write(">");
                     break;
                 case TagRenderMode.SelfClosing:
-                    content.Append("<");
+                    writer.Write("<");
-                    content.Append(TagName);
+                    writer.Write(TagName);
-                    AppendAttributes(content);
+                    AppendAttributes(writer, encoder);
-                    content.Append(" />");
+                    writer.Write(" />");
                     break;
                 default:
-                    content.Append("<");
+                    writer.Write("<");
-                    content.Append(TagName);
+                    writer.Write(TagName);
-                    AppendAttributes(content);
+                    AppendAttributes(writer, encoder);
-                    content.Append(">");
+                    writer.Write(">");
-                    content.Append(InnerHtml);
+                    InnerHtml.WriteTo(writer, encoder);
-                    content.Append("</");
+                    writer.Write("</");
-                    content.Append(TagName);
+                    writer.Write(TagName);
-                    content.Append(">");
+                    writer.Write(">");
                     break;
             }
-
-            return content;
         }
 
         private static class Html401IdUtil

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

@@ -9,8 +9,10 @@ using System.Threading.Tasks;
 using Microsoft.AspNet.Http.Internal;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
 using Microsoft.AspNet.Routing;
+using Microsoft.Framework.WebEncoders.Testing;
 using Moq;
 using Xunit;
 
@@ -57,7 +59,10 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var viewContext = TestableHtmlGenerator.GetViewContext(model: null,
                                                                    htmlGenerator: htmlGenerator,
                                                                    metadataProvider: metadataProvider);
-            var expectedPostContent = "Something" + htmlGenerator.GenerateAntiforgery(viewContext);
+            var expectedPostContent = "Something" +
+                HtmlContentUtilities.HtmlContentToString(
+                    htmlGenerator.GenerateAntiforgery(viewContext),
+                    new NullTestEncoder());
             var formTagHelper = new FormTagHelper(htmlGenerator)
             {
                 Action = "index",

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

@@ -282,6 +282,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 {
                     { "class", "form-control" },
                 },
+                TagRenderMode = TagRenderMode.SelfClosing
             };
             htmlGenerator
                 .Setup(mock => mock.GenerateCheckBox(
@@ -297,7 +298,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelper.ViewContext,
                     tagHelper.For.ModelExplorer,
                     tagHelper.For.Name))
-                .Returns(new TagBuilder("hidden"))
+                .Returns(new TagBuilder("hidden") { TagRenderMode = TagRenderMode.SelfClosing })
                 .Verifiable();
 
             // Act

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

@@ -83,7 +83,8 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 },
             };
 
-            return tagBuilder.ToHtmlContent(TagRenderMode.SelfClosing);
+            tagBuilder.TagRenderMode = TagRenderMode.SelfClosing;
+            return tagBuilder;
         }
 
         protected override IDictionary<string, object> GetValidationAttributes(

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/Rendering/TagBuilderTest.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 System.IO;
 using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.AspNet.Mvc.TestCommon;
 using Microsoft.Framework.WebEncoders.Testing;
@@ -73,36 +74,22 @@ namespace Microsoft.AspNet.Mvc.Core.Rendering
 
         [Theory]
         [MemberData(nameof(RenderingTestingData))]
-        public void ToString_IgnoresIdAttributeCase(TagRenderMode renderingMode, string expectedOutput)
+        public void WriteTo_IgnoresIdAttributeCase(TagRenderMode renderingMode, string expectedOutput)
         {
             // Arrange
             var tagBuilder = new TagBuilder("p");
-
             // An empty value id attribute should not be rendered via ToString.
             tagBuilder.Attributes.Add("ID", string.Empty);
+            tagBuilder.TagRenderMode = renderingMode;
 
             // Act
-            var value = tagBuilder.ToHtmlContent(renderingMode);
+            using (var writer = new StringWriter())
+            {
+                tagBuilder.WriteTo(writer, new NullTestEncoder());
 
-            // Assert
+                // Assert
-            Assert.Equal(expectedOutput, HtmlContentUtilities.HtmlContentToString(value, new NullTestEncoder()));
+                Assert.Equal(expectedOutput, writer.ToString());
-        }
+            }
-
-        [Theory]
-        [MemberData(nameof(RenderingTestingData))]
-        public void ToHtmlString_IgnoresIdAttributeCase(TagRenderMode renderingMode, string expectedOutput)
-        {
-            // Arrange
-            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.ToHtmlContent(renderingMode);
-
-            // Assert
-            Assert.Equal(expectedOutput, HtmlContentUtilities.HtmlContentToString(value, new NullTestEncoder()));
         }
 
         [Fact]

test/WebSites/ActivatorWebSite/TagHelpers/HiddenTagHelper.cs

@@ -30,7 +30,7 @@ namespace ActivatorWebSite.TagHelpers
 
             var content = await context.GetChildContentAsync();
 
-            output.Content.SetContent(HtmlHelper.Hidden(Name, content).ToString());
+            output.Content.SetContent(HtmlHelper.Hidden(Name, content));
         }
     }
 }

test/WebSites/ActivatorWebSite/TagHelpers/TitleTagHelper.cs

@@ -28,7 +28,7 @@ namespace ActivatorWebSite.TagHelpers
             var builder = new TagBuilder("h2");
             var title = ViewContext.ViewBag.Title;
             builder.SetInnerText(title);
-            output.PreContent.SetContent(builder.ToHtmlContent(TagRenderMode.Normal));
+            output.PreContent.SetContent(builder);
         }
     }
 }