Reacting to Razor changes for removing Generate*() method.

src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorHost.cs

@@ -92,15 +92,13 @@ namespace Microsoft.AspNet.Mvc.Razor
                     ScopeManagerBeginMethodName = nameof(TagHelperScopeManager.Begin),
                     ScopeManagerEndMethodName = nameof(TagHelperScopeManager.End),
 
-                    OutputGenerateStartTagMethodName = nameof(TagHelperOutput.GenerateStartTag),
-                    OutputGenerateContentMethodName = nameof(TagHelperOutput.GenerateContent),
-                    OutputGenerateEndTagMethodName = nameof(TagHelperOutput.GenerateEndTag),
-
                     // Can't use nameof because RazorPage is not accessible here.
                     CreateTagHelperMethodName = "CreateTagHelper",
                     StartTagHelperWritingScopeMethodName = "StartTagHelperWritingScope",
                     EndTagHelperWritingScopeMethodName = "EndTagHelperWritingScope",
-                    HtmlEncoderPropertyName = "HtmlEncoder",
+
+                    WriteTagHelperAsyncMethodName = "WriteTagHelperAsync",
+                    WriteTagHelperToAsyncMethodName = "WriteTagHelperToAsync",
                 })
             {
                 ResolveUrlMethodName = "Href",

src/Microsoft.AspNet.Mvc.Razor/RazorPage.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Security.Claims;
@@ -250,25 +251,88 @@ namespace Microsoft.AspNet.Mvc.Razor
         }
 
         /// <summary>
-        /// Writes an <see cref="ITextWriterCopyable"/> to the <see cref="Output"/>.
+        /// Writes the content of a specified <paramref name="tagHelperExecutionContext"/>.
         /// </summary>
-        /// <param name="copyableTextWriter">Contains the data to be written.</param>
+        /// <param name="tagHelperExecutionContext">The execution context containing the content.</param>
-        public void Write(ITextWriterCopyable copyableTextWriter)
+        /// <returns>
+        /// A <see cref="Task"/> that on completion writes the <paramref name="tagHelperExecutionContext"/> content.
+        /// </returns>
+        public async Task WriteTagHelperAsync([NotNull] TagHelperExecutionContext tagHelperExecutionContext)
         {
-            WriteTo(Output, copyableTextWriter);
+            await WriteTagHelperToAsync(Output, tagHelperExecutionContext);
         }
 
         /// <summary>
-        /// Writes an <see cref="ITextWriterCopyable"/> to the <paramref name="writer"/>.
+        /// Writes the content of a specified <paramref name="tagHelperExecutionContext"/> to the specified
+        /// <paramref name="writer"/>.
         /// </summary>
-        /// <param name="writer">The <see cref="TextWriter"/> to which the
+        /// <param name="writer">The <see cref="TextWriter"/> instance to write to.</param>
-        /// <paramref name="copyableTextWriter"/> is written.</param>
+        /// <param name="tagHelperExecutionContext">The execution context containing the content.</param>
-        /// <param name="copyableTextWriter">Contains the data to be written.</param>
+        /// <returns>
-        public void WriteTo([NotNull] TextWriter writer, ITextWriterCopyable copyableTextWriter)
+        /// A <see cref="Task"/> that on completion writes the <paramref name="tagHelperExecutionContext"/> content
+        /// to the <paramref name="writer"/>.
+        /// </returns>
+        public async Task WriteTagHelperToAsync(
+            [NotNull] TextWriter writer,
+            [NotNull] TagHelperExecutionContext tagHelperExecutionContext)
         {
-            if (copyableTextWriter != null)
+            var tagHelperOutput = tagHelperExecutionContext.Output;
+            var isTagNameNullOrWhitespace = string.IsNullOrWhiteSpace(tagHelperOutput.TagName);
+
+            if (!isTagNameNullOrWhitespace)
             {
-                copyableTextWriter.CopyTo(writer);
+                writer.Write('<');
+                writer.Write(tagHelperOutput.TagName);
+
+                foreach (var attribute in tagHelperOutput.Attributes)
+                {
+                    var value = HtmlEncoder.HtmlEncode(attribute.Value);
+                    writer.Write(' ');
+                    writer.Write(attribute.Key);
+                    writer.Write("=\"");
+                    writer.Write(value);
+                    writer.Write('"');
+                }
+
+                if (tagHelperOutput.SelfClosing)
+                {
+                    writer.Write(" /");
+                }
+
+                writer.Write('>');
+            }
+
+            if (isTagNameNullOrWhitespace || !tagHelperOutput.SelfClosing)
+            {
+                WriteTagHelperContentTo(writer, tagHelperOutput.PreContent);
+                if (tagHelperOutput.IsContentModified)
+                {
+                    WriteTagHelperContentTo(writer, tagHelperOutput.Content);
+                }
+                else if (tagHelperExecutionContext.ChildContentRetrieved)
+                {
+                    var childContent = await tagHelperExecutionContext.GetChildContentAsync();
+                    WriteTagHelperContentTo(writer, childContent);
+                }
+                else
+                {
+                    await tagHelperExecutionContext.ExecuteChildContentAsync();
+                }
+
+                WriteTagHelperContentTo(writer, tagHelperOutput.PostContent);
+            }
+
+            if (!isTagNameNullOrWhitespace && !tagHelperOutput.SelfClosing)
+            {
+                writer.Write(string.Format(CultureInfo.InvariantCulture, "</{0}>", tagHelperOutput.TagName));
+            }
+        }
+
+        private void WriteTagHelperContentTo(TextWriter writer, TagHelperContent content)
+        {
+            foreach (var entry in content)
+            {
+                writer.Write(entry);
             }
         }
 
@@ -310,20 +374,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                     }
                     else
                     {
-                        // This path is called when GetChildContentAsync() is called in tag helper
+                        WriteTo(writer, value.ToString());
-                        // and content is not set.
-                        var tagHelperContent = value as TagHelperContent;
-                        if (tagHelperContent != null)
-                        {
-                            foreach (var entry in tagHelperContent)
-                            {
-                                writer.Write(entry);
-                            }
-                        }
-                        else
-                        {
-                            WriteTo(writer, value.ToString());
-                        }
                     }
                 }
             }

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

@@ -85,7 +85,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
 
                     // Select this <option/> element if value attribute or content matches a selected value. Callers
                     // encode values as-needed while executing child content. But TagHelperOutput itself
-                    // encodes attribute values later, when GenerateStartTag() is called.
+                    // encodes attribute values later, when start tag is generated.
                     bool selected;
                     if (Value != null)
                     {

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/Runtime/ModelExpressionTagHelper.cs

@@ -42,7 +42,7 @@ namespace Asp
         #pragma warning disable 1998
         public override async Task ExecuteAsync()
         {
-            __tagHelperRunner = __tagHelperRunner ?? new Microsoft.AspNet.Razor.Runtime.TagHelpers.TagHelperRunner(HtmlEncoder);
+            __tagHelperRunner = __tagHelperRunner ?? new Microsoft.AspNet.Razor.Runtime.TagHelpers.TagHelperRunner();
             BeginContext(120, 2, true);
             WriteLiteral("\r\n");
             EndContext();
@@ -58,22 +58,7 @@ __Microsoft_AspNet_Mvc_Razor_InputTestTagHelper.For = CreateModelExpression(__mo
 #line hidden
             __tagHelperExecutionContext.AddTagHelperAttribute("for", __Microsoft_AspNet_Mvc_Razor_InputTestTagHelper.For);
             __tagHelperExecutionContext.Output = __tagHelperRunner.RunAsync(__tagHelperExecutionContext).Result;
-            WriteLiteral(__tagHelperExecutionContext.Output.GenerateStartTag());
+            WriteTagHelperAsync(__tagHelperExecutionContext).Wait();
-            Write(__tagHelperExecutionContext.Output.GeneratePreContent());
-            if (__tagHelperExecutionContext.Output.IsContentModified)
-            {
-                Write(__tagHelperExecutionContext.Output.GenerateContent());
-            }
-            else if (__tagHelperExecutionContext.ChildContentRetrieved)
-            {
-                Write(__tagHelperExecutionContext.GetChildContentAsync().Result);
-            }
-            else
-            {
-                __tagHelperExecutionContext.ExecuteChildContentAsync().Wait();
-            }
-            Write(__tagHelperExecutionContext.Output.GeneratePostContent());
-            WriteLiteral(__tagHelperExecutionContext.Output.GenerateEndTag());
             __tagHelperExecutionContext = __tagHelperScopeManager.End();
             BeginContext(146, 2, true);
             WriteLiteral("\r\n");
@@ -90,22 +75,7 @@ __Microsoft_AspNet_Mvc_Razor_InputTestTagHelper.For = CreateModelExpression(__mo
 #line hidden
             __tagHelperExecutionContext.AddTagHelperAttribute("for", __Microsoft_AspNet_Mvc_Razor_InputTestTagHelper.For);
             __tagHelperExecutionContext.Output = __tagHelperRunner.RunAsync(__tagHelperExecutionContext).Result;
-            WriteLiteral(__tagHelperExecutionContext.Output.GenerateStartTag());
+            WriteTagHelperAsync(__tagHelperExecutionContext).Wait();
-            Write(__tagHelperExecutionContext.Output.GeneratePreContent());
-            if (__tagHelperExecutionContext.Output.IsContentModified)
-            {
-                Write(__tagHelperExecutionContext.Output.GenerateContent());
-            }
-            else if (__tagHelperExecutionContext.ChildContentRetrieved)
-            {
-                Write(__tagHelperExecutionContext.GetChildContentAsync().Result);
-            }
-            else
-            {
-                __tagHelperExecutionContext.ExecuteChildContentAsync().Wait();
-            }
-            Write(__tagHelperExecutionContext.Output.GeneratePostContent());
-            WriteLiteral(__tagHelperExecutionContext.Output.GenerateEndTag());
             __tagHelperExecutionContext = __tagHelperScopeManager.End();
         }
         #pragma warning restore 1998

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

@@ -687,96 +687,245 @@ namespace Microsoft.AspNet.Mvc.Razor
             Assert.Same(stringCollectionWriter.Buffer.BufferEntries, buffer.BufferEntries[1]);
         }
 
-        [Fact]
+        public static TheoryData<TagHelperOutput, string> WriteTagHelper_InputData
-        public async Task Write_ITextWriterCopyable_WritesContent()
+        {
+            get
+            {
+                // parameters: TagHelperOutput, expectedOutput
+                return new TheoryData<TagHelperOutput, string>
+                {
+                    {
+                        // parameters: TagName, Attributes, SelfClosing, PreContent, Content, PostContent
+                        GetTagHelperOutput("div", new Dictionary<string, string>(), false, null, "Hello World!", null),
+                        "<div>Hello World!</div>"
+                    },
+                    {
+                        GetTagHelperOutput(null, new Dictionary<string, string>(), false, null, "Hello World!", null),
+                        "Hello World!"
+                    },
+                    {
+                        GetTagHelperOutput("  ", new Dictionary<string, string>(), false, null, "Hello World!", null),
+                        "Hello World!"
+                    },
+                    {
+                        GetTagHelperOutput(
+                            "p",
+                            new Dictionary<string, string>() { { "test", "testVal" } },
+                            false,
+                            null,
+                            "Hello World!",
+                            null),
+                        "<p test=\"testVal\">Hello World!</p>"
+                    },
+                    {
+                        GetTagHelperOutput(
+                            "p",
+                            new Dictionary<string, string>() { { "test", "testVal" }, { "something", "  spaced  " } },
+                            false,
+                            null,
+                            "Hello World!",
+                            null),
+                        "<p test=\"testVal\" something=\"  spaced  \">Hello World!</p>"
+                    },
+                    {
+                        GetTagHelperOutput(
+                            "p",
+                            new Dictionary<string, string>() { { "test", "testVal" } },
+                            true,
+                            null,
+                            "Hello World!",
+                            null),
+                        "<p test=\"testVal\" />"
+                    },
+                    {
+                        GetTagHelperOutput(
+                            "p",
+                            new Dictionary<string, string>() { { "test", "testVal" }, { "something", "  spaced  " } },
+                            true,
+                            null,
+                            "Hello World!",
+                            null),
+                        "<p test=\"testVal\" something=\"  spaced  \" />"
+                    },
+                    {
+                        GetTagHelperOutput("p", new Dictionary<string, string>(), false, "Hello World!", null, null),
+                        "<p>Hello World!</p>"
+                    },
+                    {
+                        GetTagHelperOutput("p", new Dictionary<string, string>(), false, null, "Hello World!", null),
+                        "<p>Hello World!</p>"
+                    },
+                    {
+                        GetTagHelperOutput("p", new Dictionary<string, string>(), false, null, null, "Hello World!"),
+                        "<p>Hello World!</p>"
+                    },
+                    {
+                        GetTagHelperOutput("p", new Dictionary<string, string>(), false, "Hello", "Test", "World!"),
+                        "<p>HelloTestWorld!</p>"
+                    },
+                    {
+                        GetTagHelperOutput("p", new Dictionary<string, string>(), true, "Hello", "Test", "World!"),
+                        "<p />"
+                    },
+                    {
+                        GetTagHelperOutput("custom", new Dictionary<string, string>(), false, "Hello", "Test", "World!"),
+                        "<custom>HelloTestWorld!</custom>"
+                    },
+                    {
+                        GetTagHelperOutput("random", new Dictionary<string, string>(), true, "Hello", "Test", "World!"),
+                        "<random />"
+                    }
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(WriteTagHelper_InputData))]
+        public async Task WriteTagHelperAsync_WritesFormattedTagHelper(TagHelperOutput output, string expected)
         {
             // Arrange
-            // This writer uses BufferEntryCollection underneath and so can copy the buffer.
             var writer = new StringCollectionTextWriter(Encoding.UTF8);
             var context = CreateViewContext(writer);
-            var expectedContent = "Hello World!";
+            var tagHelperExecutionContext = new TagHelperExecutionContext(
-            var contentToBeCopied = new DefaultTagHelperContent().SetContent("Hello ").Append("World!");
+                tagName: output.TagName,
+                selfClosing: output.SelfClosing,
+                items: new Dictionary<object, object>(),
+                uniqueId: string.Empty,
+                executeChildContentAsync: () => Task.FromResult(result: true),
+                startTagHelperWritingScope: () => { },
+                endTagHelperWritingScope: () => new DefaultTagHelperContent());
+            tagHelperExecutionContext.Output = output;
 
             // Act
             var page = CreatePage(p =>
             {
-                p.Write((ITextWriterCopyable)contentToBeCopied);
+                p.HtmlEncoder = new HtmlEncoder();
+                p.WriteTagHelperAsync(tagHelperExecutionContext).Wait();
             }, context);
             await page.ExecuteAsync();
 
             // Assert
-            Assert.Equal(expectedContent, writer.ToString());
+            Assert.Equal(expected, writer.ToString());
-            Assert.Equal(2, writer.Buffer.BufferEntries.Count);
-            var expectedList = new List<object>();
-            expectedList.Add("Hello ");
-            expectedList.Add("World!");
-            Assert.Equal(expectedList, writer.Buffer.BufferEntries);
         }
 
-        [Fact]
+        [Theory]
-        public async Task Write_ITextWriterCopyable_WritesContent_AsString()
+        // This is a scenario where GetChildContentAsync is called.
+        [InlineData(true, "HelloWorld!", "<p>HelloWorld!</p>")]
+        // This is a scenario where ExecuteChildContentAsync is called.
+        [InlineData(false, "HelloWorld!", "<p></p>")]
+        public async Task WriteTagHelperAsync_WritesContentAppropriately(
+            bool childContentRetrieved, string input, string expected)
         {
             // Arrange
-            // This writer stores the data as a string.
+            var defaultTagHelperContent = new DefaultTagHelperContent();
-            var writer = new StringWriter();
-            var context = CreateViewContext(writer);
-            var expectedContent = "Hello World!";
-            var contentToBeCopied = new DefaultTagHelperContent().SetContent("Hello ").Append("World!");
-
-            // Act
-            var page = CreatePage(p =>
-            {
-                p.Write((ITextWriterCopyable)contentToBeCopied);
-            }, context);
-            await page.ExecuteAsync();
-
-            // Assert
-            Assert.Equal(expectedContent, writer.ToString());
-        }
-
-        [Fact]
-        public async Task WriteTo_ITextWriterCopyable_WritesContent_ToSpecifiedWriter()
-        {
-            // Arrange
-            var writer = new StringWriter();
-            var expectedContent = "Hello World!";
-            var contentToBeCopied = new DefaultTagHelperContent().SetContent("Hello ").Append("World!");
-
-            // Act
-            var page = CreatePage(p =>
-            {
-                p.WriteTo(writer, (ITextWriterCopyable)contentToBeCopied);
-            });
-            await page.ExecuteAsync();
-
-            // Assert
-            Assert.Equal(expectedContent, writer.ToString());
-        }
-
-        [Fact]
-        public async Task Write_TagHelperContent_WritesContent()
-        {
-            // Arrange
-            // This writer uses BufferEntryCollection underneath and so can copy the buffer.
             var writer = new StringCollectionTextWriter(Encoding.UTF8);
             var context = CreateViewContext(writer);
-            var expectedContent = "Hello World!";
+            var tagHelperExecutionContext = new TagHelperExecutionContext(
-            var contentToBeCopied = new DefaultTagHelperContent().SetContent("Hello ").Append("World!");
+                tagName: "p",
+                selfClosing: false,
+                items: new Dictionary<object, object>(),
+                uniqueId: string.Empty,
+                executeChildContentAsync: () => {
+                    defaultTagHelperContent.SetContent(input);
+                    return Task.FromResult(result: true);
+                },
+                startTagHelperWritingScope: () => { },
+                endTagHelperWritingScope: () => defaultTagHelperContent);
+            tagHelperExecutionContext.Output =
+                new TagHelperOutput("p", new Dictionary<string, string>());
+            if (childContentRetrieved)
+            {
+                await tagHelperExecutionContext.GetChildContentAsync();
+            }
 
             // Act
             var page = CreatePage(p =>
             {
-                p.Write(contentToBeCopied);
+                p.HtmlEncoder = new HtmlEncoder();
+                p.WriteTagHelperAsync(tagHelperExecutionContext).Wait();
             }, context);
             await page.ExecuteAsync();
 
             // Assert
-            Assert.Equal(expectedContent, writer.ToString());
+            Assert.Equal(expected, writer.ToString());
-            Assert.Equal(2, writer.Buffer.BufferEntries.Count);
+        }
-            var expectedList = new List<object>();
+
-            expectedList.Add("Hello ");
+        [Fact]
-            expectedList.Add("World!");
+        public async Task WriteTagHelperToAsync_WritesToSpecifiedWriter()
-            Assert.Equal(expectedList, writer.Buffer.BufferEntries);
+        {
+            // Arrange
+            var writer = new StringCollectionTextWriter(Encoding.UTF8);
+            var context = CreateViewContext(new StringWriter());
+            var tagHelperExecutionContext = new TagHelperExecutionContext(
+                tagName: "p",
+                selfClosing: false,
+                items: new Dictionary<object, object>(),
+                uniqueId: string.Empty,
+                executeChildContentAsync: () => { return Task.FromResult(result: true); },
+                startTagHelperWritingScope: () => { },
+                endTagHelperWritingScope: () => new DefaultTagHelperContent());
+            tagHelperExecutionContext.Output =
+                new TagHelperOutput("p", new Dictionary<string, string>());
+            tagHelperExecutionContext.Output.Content.SetContent("Hello World!");
+
+            // Act
+            var page = CreatePage(p =>
+            {
+                p.WriteTagHelperToAsync(writer, tagHelperExecutionContext).Wait();
+            }, context);
+            await page.ExecuteAsync();
+
+            // Assert
+            Assert.Equal("<p>Hello World!</p>", writer.ToString());
+        }
+
+        [Theory]
+        [MemberData(nameof(WriteTagHelper_InputData))]
+        public async Task WriteTagHelperToAsync_WritesFormattedTagHelper(TagHelperOutput output, string expected)
+        {
+            // Arrange
+            var writer = new StringCollectionTextWriter(Encoding.UTF8);
+            var context = CreateViewContext(new StringWriter());
+            var tagHelperExecutionContext = new TagHelperExecutionContext(
+                tagName: output.TagName,
+                selfClosing: output.SelfClosing,
+                items: new Dictionary<object, object>(),
+                uniqueId: string.Empty,
+                executeChildContentAsync: () => Task.FromResult(result: true),
+                startTagHelperWritingScope: () => { },
+                endTagHelperWritingScope: () => new DefaultTagHelperContent());
+            tagHelperExecutionContext.Output = output;
+
+            // Act
+            var page = CreatePage(p =>
+            {
+                p.HtmlEncoder = new HtmlEncoder();
+                p.WriteTagHelperToAsync(writer, tagHelperExecutionContext).Wait();
+            }, context);
+            await page.ExecuteAsync();
+
+            // Assert
+            Assert.Equal(expected, writer.ToString());
+        }
+
+        private static TagHelperOutput GetTagHelperOutput(
+            string tagName,
+            IDictionary<string, string> attributes,
+            bool selfClosing,
+            string preContent,
+            string content,
+            string postContent)
+        {
+            var output = new TagHelperOutput(tagName, attributes)
+            {
+                SelfClosing = selfClosing
+            };
+
+            output.PreContent.SetContent(preContent);
+            output.Content.SetContent(content);
+            output.PostContent.SetContent(postContent);
+
+            return output;
         }
 
         private static TestableRazorPage CreatePage(Action<TestableRazorPage> executeAction,

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

@@ -47,8 +47,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 {
                     { "id", "myanchor" },
                     { "asp-route-foo", "bar" },
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             output.Content.SetContent("Something");
 
             var urlHelper = new Mock<IUrlHelper>();
@@ -98,8 +97,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 });
             var output = new TagHelperOutput(
                 "a",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.Content.SetContent(string.Empty);
 
             var generator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
@@ -141,8 +139,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 });
             var output = new TagHelperOutput(
                 "a",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.Content.SetContent(string.Empty);
 
             var generator = new Mock<IHtmlGenerator>();
@@ -186,8 +183,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 attributes: new Dictionary<string, string>()
                 {
                     { "href", "http://www.contoso.com" }
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             if (propertyName == "asp-route-")
             {
                 output.Attributes.Add("asp-route-foo", "bar");
@@ -222,8 +218,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             typeof(AnchorTagHelper).GetProperty(propertyName).SetValue(anchorTagHelper, "Home");
             var output = new TagHelperOutput(
                 "a",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             var expectedErrorMessage = "Cannot determine an 'href' attribute for <a>. An <a> with a specified " +
                 "'asp-route' must not have an 'asp-action' or 'asp-controller' attribute.";
 

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

@@ -245,7 +245,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var childContent = "original-child-content";
             var cache = new MemoryCache(new MemoryCacheOptions());
             var tagHelperContext1 = GetTagHelperContext(id, childContent);
-            var tagHelperOutput1 = new TagHelperOutput("cache", new Dictionary<string, string>(), new HtmlEncoder());
+            var tagHelperOutput1 = new TagHelperOutput("cache", new Dictionary<string, string>());
             var cacheTagHelper1 = new CacheTagHelper
             {
                 VaryByQuery = "key1,key2",
@@ -266,7 +266,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
 
             // Arrange - 2
             var tagHelperContext2 = GetTagHelperContext(id, "different-content");
-            var tagHelperOutput2 = new TagHelperOutput("cache", new Dictionary<string, string>(), new HtmlEncoder());
+            var tagHelperOutput2 = new TagHelperOutput("cache", new Dictionary<string, string>());
             var cacheTagHelper2 = new CacheTagHelper
             {
                 VaryByQuery = "key1,key2",
@@ -295,8 +295,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var cache = new MemoryCache(new MemoryCacheOptions());
             var tagHelperContext1 = GetTagHelperContext(id, childContent1);
             var tagHelperOutput1 = new TagHelperOutput("cache",
-                                                       new Dictionary<string, string> { { "attr", "value" } },
+                                                       new Dictionary<string, string> { { "attr", "value" } });
-                                                       new HtmlEncoder());
             tagHelperOutput1.PreContent.Append("<cache>");
             tagHelperOutput1.PostContent.SetContent("</cache>");
             var cacheTagHelper1 = new CacheTagHelper
@@ -321,8 +320,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var tagHelperContext2 = GetTagHelperContext(id, childContent2);
             var tagHelperOutput2 = new TagHelperOutput(
                 "cache",
-                new Dictionary<string, string> { { "attr", "value" } },
+                new Dictionary<string, string> { { "attr", "value" } });
-                new HtmlEncoder());
             tagHelperOutput2.PreContent.SetContent("<cache>");
             tagHelperOutput2.PostContent.SetContent("</cache>");
             var cacheTagHelper2 = new CacheTagHelper
@@ -532,8 +530,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var cache = new MemoryCache(new MemoryCacheOptions { Clock = clock.Object });
             var tagHelperContext1 = GetTagHelperContext(id, childContent1);
             var tagHelperOutput1 = new TagHelperOutput("cache",
-                                                       new Dictionary<string, string> { { "attr", "value" } },
+                                                       new Dictionary<string, string> { { "attr", "value" } });
-                                                       new HtmlEncoder());
             tagHelperOutput1.PreContent.SetContent("<cache>");
             tagHelperOutput1.PostContent.SetContent("</cache>");
             var cacheTagHelper1 = new CacheTagHelper
@@ -556,8 +553,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var childContent2 = "different-content";
             var tagHelperContext2 = GetTagHelperContext(id, childContent2);
             var tagHelperOutput2 = new TagHelperOutput("cache",
-                                                       new Dictionary<string, string> { { "attr", "value" } },
+                                                       new Dictionary<string, string> { { "attr", "value" } });
-                                                       new HtmlEncoder());
             tagHelperOutput2.PreContent.SetContent("<cache>");
             tagHelperOutput2.PostContent.SetContent("</cache>");
             var cacheTagHelper2 = new CacheTagHelper
@@ -591,8 +587,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var cache = new MemoryCache(new MemoryCacheOptions { Clock = clock.Object });
             var tagHelperContext1 = GetTagHelperContext(id, childContent1);
             var tagHelperOutput1 = new TagHelperOutput("cache",
-                                                       new Dictionary<string, string> { { "attr", "value" } },
+                                                       new Dictionary<string, string> { { "attr", "value" } });
-                                                       new HtmlEncoder());
             tagHelperOutput1.PreContent.SetContent("<cache>");
             tagHelperOutput1.PostContent.SetContent("</cache>");
             var cacheTagHelper1 = new CacheTagHelper
@@ -616,8 +611,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var childContent2 = "different-content";
             var tagHelperContext2 = GetTagHelperContext(id, childContent2);
             var tagHelperOutput2 = new TagHelperOutput("cache",
-                                                       new Dictionary<string, string> { { "attr", "value" } },
+                                                       new Dictionary<string, string> { { "attr", "value" } });
-                                                       new HtmlEncoder());
             tagHelperOutput2.PreContent.SetContent("<cache>");
             tagHelperOutput2.PostContent.SetContent("</cache>");
             var cacheTagHelper2 = new CacheTagHelper
@@ -650,8 +644,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var cache = new MemoryCache(new MemoryCacheOptions { Clock = clock.Object });
             var tagHelperContext1 = GetTagHelperContext(id, childContent1);
             var tagHelperOutput1 = new TagHelperOutput("cache",
-                                                       new Dictionary<string, string> { { "attr", "value" } },
+                                                       new Dictionary<string, string> { { "attr", "value" } });
-                                                       new HtmlEncoder());
             tagHelperOutput1.PreContent.SetContent("<cache>");
             tagHelperOutput1.PostContent.SetContent("</cache>");
             var cacheTagHelper1 = new CacheTagHelper
@@ -675,8 +668,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var childContent2 = "different-content";
             var tagHelperContext2 = GetTagHelperContext(id, childContent2);
             var tagHelperOutput2 = new TagHelperOutput("cache",
-                                                       new Dictionary<string, string> { { "attr", "value" } },
+                                                       new Dictionary<string, string> { { "attr", "value" } });
-                                                       new HtmlEncoder());
             tagHelperOutput2.PreContent.SetContent("<cache>");
             tagHelperOutput2.PostContent.SetContent("</cache>");
             var cacheTagHelper2 = new CacheTagHelper
@@ -720,8 +712,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     return Task.FromResult<TagHelperContent>(expectedContent);
                 });
             var tagHelperOutput = new TagHelperOutput("cache",
-                                                       new Dictionary<string, string> { { "attr", "value" } },
+                                                       new Dictionary<string, string> { { "attr", "value" } });
-                                                       new HtmlEncoder());
             tagHelperOutput.PreContent.SetContent("<cache>");
             tagHelperOutput.PostContent.SetContent("</cache>");
             var cacheTagHelper = new CacheTagHelper

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

@@ -151,7 +151,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers.Test
         {
             attributes = attributes ?? new Dictionary<string, string>();
 
-            return new TagHelperOutput(tagName, attributes, new HtmlEncoder());
+            return new TagHelperOutput(tagName, attributes);
         }
     }
 }

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

@@ -49,8 +49,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 {
                     { "id", "myform" },
                     { "asp-route-foo", "bar" },
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             output.PostContent.SetContent("Something");
             var urlHelper = new Mock<IUrlHelper>();
             urlHelper
@@ -111,8 +110,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 });
             var output = new TagHelperOutput(
                 "form",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             var generator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             generator
                 .Setup(mock => mock.GenerateForm(
@@ -168,8 +166,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 {
                     { "asp-route-val", "hello" },
                     { "asp-roUte--Foo", "bar" }
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             output.Attributes.Add(expectedAttribute);
 
             var generator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
@@ -235,8 +232,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 });
             var output = new TagHelperOutput(
                 "form",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             var generator = new Mock<IHtmlGenerator>(MockBehavior.Strict);
             generator
                 .Setup(mock => mock.GenerateForm(viewContext, "Index", "Home", null, "POST", null))
@@ -279,8 +275,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                                              attributes: new Dictionary<string, string>
                                              {
                                                  { "aCTiON", htmlAction },
-                                             },
+                                             });
-                                             htmlEncoder: new HtmlEncoder());
 
             var context = new TagHelperContext(
                 allAttributes: new Dictionary<string, object>()
@@ -336,8 +331,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                                              attributes: new Dictionary<string, string>
                                              {
                                                  { "aCTiON", "my-action" },
-                                             },
+                                             });
-                                             htmlEncoder: new HtmlEncoder());
             var context = new TagHelperContext(
                 allAttributes: new Dictionary<string, object>(),
                 items: new Dictionary<object, object>(),
@@ -379,8 +373,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 attributes: new Dictionary<string, string>
                 {
                     { "action", "my-action" },
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             if (propertyName == "asp-route-")
             {
                 tagHelperOutput.Attributes.Add("asp-route-foo", "bar");

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

@@ -109,7 +109,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             {
                 { "class", "form-control" },
             };
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, originalAttributes)
             {
                 SelfClosing = false,
             };
@@ -170,7 +170,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             {
                 { "class", "form-control" },
             };
-            var output = new TagHelperOutput(originalTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(originalTagName, originalAttributes)
             {
                 SelfClosing = true,
             };
@@ -266,7 +266,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             {
                 { "class", "form-control" },
             };
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, originalAttributes)
             {
                 SelfClosing = false,
             };
@@ -365,7 +365,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             {
                 { "class", "form-control" },
             };
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, originalAttributes)
             {
                 SelfClosing = false,
             };
@@ -461,7 +461,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             {
                 { "class", "form-control" },
             };
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, originalAttributes)
             {
                 SelfClosing = false,
             };
@@ -566,7 +566,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             {
                 { "class", "form-control" },
             };
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, originalAttributes)
             {
                 SelfClosing = false,
             };
@@ -643,7 +643,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
 
-            var output = new TagHelperOutput(expectedTagName, expectedAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, expectedAttributes)
             {
                 SelfClosing = false,
             };
@@ -709,7 +709,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent("Something");
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder());
+            var output = new TagHelperOutput(expectedTagName, originalAttributes);
             var tagHelper = new InputTagHelper
             {
                 Format = "{0}",

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

@@ -200,7 +200,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             {
                 { "class", "form-control" },
             };
-            var output = new TagHelperOutput(expectedTagName, htmlAttributes, new HtmlEncoder());
+            var output = new TagHelperOutput(expectedTagName, htmlAttributes);
             output.PreContent.SetContent(expectedPreContent);
             output.PostContent.SetContent(expectedPostContent);
 
@@ -259,7 +259,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent("Something");
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(expectedTagName, expectedAttributes, new HtmlEncoder());
+            var output = new TagHelperOutput(expectedTagName, expectedAttributes);
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent(expectedPostContent);

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

@@ -403,7 +403,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
         {
             attributes = attributes ?? new Dictionary<string, string>();
 
-            return new TagHelperOutput(tagName, attributes, new HtmlEncoder());
+            return new TagHelperOutput(tagName, attributes);
         }
 
         private static IHostingEnvironment MakeHostingEnvironment()

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

@@ -6,7 +6,6 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
-using Microsoft.Framework.WebEncoders;
 using Xunit;
 
 namespace Microsoft.AspNet.Mvc.TagHelpers
@@ -14,80 +13,337 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
     public class OptionTagHelperTest
     {
         // Original content, selected attribute, value attribute, selected values (to place in FormContext.FormData)
-        // and expected output (concatenation of TagHelperOutput generations).
+        // and expected tag helper output.
-        public static TheoryData<string, string, string, ICollection<string>, string> GeneratesExpectedDataSet
+        public static TheoryData<string, string, string, IEnumerable<string>, TagHelperOutput> GeneratesExpectedDataSet
         {
             get
             {
-                return new TheoryData<string, string, string, ICollection<string>, string>
+                return new TheoryData<string, string, string, IEnumerable<string>, TagHelperOutput>
                 {
-                    { null, null, null, null,
+                    // original content, selected, value, selected values,
-                        "<not-option label=\"my-label\"></not-option>" },
+                    // expected tag helper output - attributes, content
-                    { null, string.Empty, "value", null,
+                    {
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"\"></not-option>" },
+                        null, null, null, null,
-                    { null, "selected", "value", null,
+                        GetTagHelperOutput(
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"selected\"></not-option>" },
+                            "not-option",
-                    { null, null, "value", new string[0],
+                            new Dictionary<string, string>
-                        "<not-option label=\"my-label\" value=\"value\"></not-option>" },
+                            {
-                    { null, null, "value", new [] { string.Empty, },
+                                { "label", "my-label" }
-                        "<not-option label=\"my-label\" value=\"value\"></not-option>" },
+                            },
-                    { null, string.Empty, "value", new [] { string.Empty, },
+                            "")
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"\"></not-option>" },
+                    },
-                    { null, null, "value", new [] { "value", },
+                    {
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"selected\"></not-option>" },
+                        null, string.Empty, "value", null,
-                    { null, null, "value", new [] { string.Empty, "value", },
+                        GetTagHelperOutput(
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"selected\"></not-option>" },
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "" }
+                            },
+                            "")
+                    },
+                    {
+                        null, "selected", "value", null,
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "selected" }
+                            },
+                            "")
+                    },
+                    {
+                        null, null, "value", Enumerable.Empty<string>(),
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }
+                            },
+                            "")
+                    },
+                    {
+                        null, null, "value", new [] { string.Empty, },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }
+                            },
+                            "")
+                    },
+                    {
+                        null, string.Empty, "value", new [] { string.Empty, },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "" }
+                            },
+                            "")
+                    },
+                    {
+                        null, null, "value", new [] { "value", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "selected" }
+                            },
+                            "")
+                    },
+                    {
+                        null, null, "value", new [] { string.Empty, "value", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "selected" }
+                            },
+                            "")
+                    },
+                    {
+                        string.Empty, null, null, null,
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }
+                            },
+                        "")
+                    },
+                    {
+                        string.Empty, string.Empty, null, null,
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "" }
+                            },
+                            "")
+                    },
+                    {
+                        string.Empty, "selected", null, null,
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "selected" }
+                            },
+                            "")
+                    },
+                    {
+                        string.Empty, null, null, Enumerable.Empty<string>(),
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }
+                            },
+                            "")
+                    },
+                    {
+                        string.Empty, null, null, new [] { string.Empty, },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "selected" }
+                            },
+                            "")
+                    },
+                    {
+                        string.Empty, string.Empty, null, new [] { string.Empty, },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "" }
+                            },
+                            "")
+                    },
+                    {
+                        string.Empty, null, null, new [] { "text", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }
+                            },
+                            "")
+                    },
+                    {
+                        string.Empty, null, null, new [] { string.Empty, "text", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "selected" }
+                            },
+                            "")
+                    },
 
-                    { string.Empty, null, null, null,
+                    {
-                        "<not-option label=\"my-label\"></not-option>" },
+                        "text", null, null, null,
-                    { string.Empty, string.Empty, null, null,
+                        GetTagHelperOutput(
-                        "<not-option label=\"my-label\" selected=\"\"></not-option>" },
+                            "not-option",
-                    { string.Empty, "selected", null, null,
+                            new Dictionary<string, string>
-                        "<not-option label=\"my-label\" selected=\"selected\"></not-option>" },
+                            {
-                    { string.Empty, null, null, new string[0],
+                                { "label", "my-label" }
-                        "<not-option label=\"my-label\"></not-option>" },
+                            },
-                    { string.Empty, null, null, new [] { string.Empty, },
+                            "text")
-                        "<not-option label=\"my-label\" selected=\"selected\"></not-option>" },
+                    },
-                    { string.Empty, string.Empty, null, new [] { string.Empty, },
+                    {
-                        "<not-option label=\"my-label\" selected=\"\"></not-option>" },
+                        "text", string.Empty, null, null,
-                    { string.Empty, null, null, new [] { "text", },
+                        GetTagHelperOutput(
-                        "<not-option label=\"my-label\"></not-option>" },
+                            "not-option",
-                    { string.Empty, null, null, new [] { string.Empty, "text", },
+                            new Dictionary<string, string>
-                        "<not-option label=\"my-label\" selected=\"selected\"></not-option>" },
+                            {
+                                { "label", "my-label" }, { "selected", "" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", "selected", null, null,
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "selected" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", null, null, Enumerable.Empty<string>(),
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", null, null, new [] { string.Empty, },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", null, null, new [] { "text", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "selected" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", string.Empty, null, new [] { "text", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", null, null, new [] { string.Empty, "text", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "selected", "selected" }
+                            },
+                            "text")
+                    },
 
-                    { "text", null, null, null,
+                    {
-                        "<not-option label=\"my-label\">text</not-option>" },
+                        "text", string.Empty, "value", null,
-                    { "text", string.Empty, null, null,
+                        GetTagHelperOutput(
-                        "<not-option label=\"my-label\" selected=\"\">text</not-option>" },
+                            "not-option",
-                    { "text", "selected", null, null,
+                            new Dictionary<string, string>
-                        "<not-option label=\"my-label\" selected=\"selected\">text</not-option>" },
+                            {
-                    { "text", null, null, new string[0],
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "" }
-                        "<not-option label=\"my-label\">text</not-option>" },
+                            },
-                    { "text", null, null, new [] { string.Empty, },
+                            "text")
-                        "<not-option label=\"my-label\">text</not-option>" },
+                    },
-                    { "text", null, null, new [] { "text", },
+                    {
-                        "<not-option label=\"my-label\" selected=\"selected\">text</not-option>" },
+                        "text", "selected", "value", null,
-                    { "text", string.Empty, null, new [] { "text", },
+                        GetTagHelperOutput(
-                        "<not-option label=\"my-label\" selected=\"\">text</not-option>" },
+                            "not-option",
-                    { "text", null, null, new [] { string.Empty, "text", },
+                            new Dictionary<string, string>
-                        "<not-option label=\"my-label\" selected=\"selected\">text</not-option>" },
+                            {
-
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "selected" }
-                    { "text", string.Empty, "value", null,
+                            },
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"\">text</not-option>" },
+                            "text")
-                    { "text", "selected", "value", null,
+                    },
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"selected\">text</not-option>" },
+                    {
-                    { "text", null, "value", new string[0],
+                        "text", null, "value", Enumerable.Empty<string>(),
-                        "<not-option label=\"my-label\" value=\"value\">text</not-option>" },
+                        GetTagHelperOutput(
-                    { "text", null, "value", new [] { string.Empty, },
+                            "not-option",
-                        "<not-option label=\"my-label\" value=\"value\">text</not-option>" },
+                            new Dictionary<string, string>
-                    { "text", string.Empty, "value", new [] { string.Empty, },
+                            {
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"\">text</not-option>" },
+                                { "label", "my-label" }, { "value", "value" }
-                    { "text", null, "value", new [] { "text", },
+                            },
-                        "<not-option label=\"my-label\" value=\"value\">text</not-option>" },
+                            "text")
-                    { "text", null, "value", new [] { "value", },
+                    },
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"selected\">text</not-option>" },
+                    {
-                    { "text", null, "value", new [] { string.Empty, "value", },
+                        "text", null, "value", new [] { string.Empty, },
-                        "<not-option label=\"my-label\" value=\"value\" selected=\"selected\">text</not-option>" },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", string.Empty, "value", new [] { string.Empty, },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", null, "value", new [] { "text", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", null, "value", new [] { "value", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "selected" }
+                            },
+                            "text")
+                    },
+                    {
+                        "text", null, "value", new [] { string.Empty, "value", },
+                        GetTagHelperOutput(
+                            "not-option",
+                            new Dictionary<string, string>
+                            {
+                                { "label", "my-label" }, { "value", "value" }, { "selected", "selected" }
+                            },
+                            "text")
+                    }
                 };
             }
         }
@@ -121,15 +377,14 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             string originalContent,
             string selected,
             string value,
-            ICollection<string> selectedValues,
+            IEnumerable<string> selectedValues,
-            string expectedOutput)
+            TagHelperOutput expectedTagHelperOutput)
         {
             // Arrange
             var originalAttributes = new Dictionary<string, string>
             {
                 { "label", "my-label" },
             };
-            var expectedTagName = "not-option";
 
             var contextAttributes = new Dictionary<string, object>
             {
@@ -147,7 +402,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent(originalContent);
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagHelperOutput.TagName, originalAttributes)
             {
                 SelfClosing = false,
             };
@@ -172,11 +427,13 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             await tagHelper.ProcessAsync(tagHelperContext, output);
 
             // Assert
-            Assert.Equal(
+            Assert.Equal(expectedTagHelperOutput.TagName, output.TagName);
-                expectedOutput,
+            Assert.Equal(expectedTagHelperOutput.Content.GetContent(), output.Content.GetContent());
-                output.GenerateStartTag() +
+            Assert.Equal(expectedTagHelperOutput.Attributes.Count, output.Attributes.Count);
-                (output.GenerateContent() as TagHelperContent).GetContent() +
+            foreach (var attribute in output.Attributes)
-                output.GenerateEndTag());
+            {
+                Assert.Contains(attribute, expectedTagHelperOutput.Attributes);
+            }
         }
 
         [Theory]
@@ -185,8 +442,8 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             string originalContent,
             string selected,
             string value,
-            ICollection<string> selectedValues,
+            IEnumerable<string> selectedValues,
-            string ignored)
+            TagHelperOutput ignored)
         {
             // Arrange
             var originalAttributes = new Dictionary<string, string>
@@ -213,7 +470,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent(originalContent);
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(originalTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(originalTagName, originalAttributes)
             {
                 SelfClosing = false,
             };
@@ -246,8 +503,8 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             string originalContent,
             string selected,
             string value,
-            ICollection<string> ignoredValues,
+            IEnumerable<string> ignoredValues,
-            string ignoredOutput)
+            TagHelperOutput ignoredOutput)
         {
             // Arrange
             var originalAttributes = new Dictionary<string, string>
@@ -274,7 +531,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent(originalContent);
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(originalTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(originalTagName, originalAttributes)
             {
                 SelfClosing = false,
             };
@@ -292,5 +549,14 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Tag helper would throw an NRE if it used ViewContext or Generator values.
             await tagHelper.ProcessAsync(tagHelperContext, output);
         }
+
+        private static TagHelperOutput GetTagHelperOutput(
+            string tagName, IDictionary<string, string> attributes, string content)
+        {
+            var tagHelperOutput = new TagHelperOutput(tagName, attributes);
+            tagHelperOutput.Content.SetContent(content);
+
+            return tagHelperOutput;
+        }
     }
 }

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

@@ -476,7 +476,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
         {
             attributes = attributes ?? new Dictionary<string, string>();
 
-            return new TagHelperOutput(tagName, attributes, new HtmlEncoder());
+            return new TagHelperOutput(tagName, attributes);
         }
 
         private TagHelperLogger<ScriptTagHelper> CreateLogger()

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

@@ -208,7 +208,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent("Something");
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, originalAttributes)
             {
                 SelfClosing = true,
             };
@@ -298,7 +298,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent("Something");
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, originalAttributes)
             {
                 SelfClosing = true,
             };
@@ -402,7 +402,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent("Something");
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, originalAttributes)
             {
                 SelfClosing = true
             };
@@ -492,7 +492,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
 
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder());
+            var output = new TagHelperOutput(expectedTagName, originalAttributes);
             var metadataProvider = new EmptyModelMetadataProvider();
             string model = null;
             var modelExplorer = metadataProvider.GetModelExplorerForType(typeof(string), model);
@@ -562,7 +562,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent("Something");
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(tagName, originalAttributes, new HtmlEncoder());
+            var output = new TagHelperOutput(tagName, originalAttributes);
             var metadataProvider = new EmptyModelMetadataProvider();
             var modelExplorer = metadataProvider.GetModelExplorerForType(modelType, model);
             var modelExpression = new ModelExpression(propertyName, modelExplorer);
@@ -622,7 +622,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent("Something");
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(expectedTagName, originalAttributes, new HtmlEncoder());
+            var output = new TagHelperOutput(expectedTagName, originalAttributes);
             var tagHelper = new SelectTagHelper
             {
                 Items = Enumerable.Empty<SelectListItem>(),

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

@@ -21,8 +21,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput(
                 "p",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             var tagHelperContext = new TagHelperContext(
                 allAttributes: new Dictionary<string, object>(StringComparer.Ordinal)
                 {
@@ -56,8 +55,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 attributes: new Dictionary<string, string>()
                 {
                     { attributeName, "world2" }
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             var expectedAttribute = new KeyValuePair<string, string>(attributeName, "world2");
             var tagHelperContext = new TagHelperContext(
                 allAttributes: new Dictionary<string, object>(StringComparer.Ordinal)
@@ -91,8 +89,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 {
                     { "route-Hello", "World" },
                     { "Route-I", "Am" }
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             var expectedAttribute = new KeyValuePair<string, string>("type", "btn");
             tagHelperOutput.Attributes.Add(expectedAttribute);
             var attributes = tagHelperOutput.FindPrefixedAttributes("route-");
@@ -115,8 +112,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 {
                     { "routeHello", "World" },
                     { "Routee-I", "Am" }
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
 
             // Act
             var attributes = tagHelperOutput.FindPrefixedAttributes("route-");
@@ -135,8 +131,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput(
                 "p",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             var expectedAttribute = new KeyValuePair<string, string>("type", "btn");
             tagHelperOutput.Attributes.Add(expectedAttribute);
 
@@ -157,8 +152,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput(
                 "p",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             tagHelperOutput.Attributes.Add("class", "Hello");
 
             var tagBuilder = new TagBuilder("p", new HtmlEncoder());
@@ -184,8 +178,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput(
                 "p",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             tagHelperOutput.Attributes.Add(originalName, "Hello");
 
             var tagBuilder = new TagBuilder("p", new HtmlEncoder());
@@ -205,8 +198,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput(
                 "p",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
 
             var tagBuilder = new TagBuilder("p", new HtmlEncoder());
             var expectedAttribute = new KeyValuePair<string, string>("visible", "val < 3");
@@ -226,8 +218,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput(
                 "p",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
 
             var tagBuilder = new TagBuilder("p", new HtmlEncoder());
             var expectedAttribute1 = new KeyValuePair<string, string>("class", "btn");
@@ -252,8 +243,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput(
                 "p",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             var expectedAttribute = new KeyValuePair<string, string>("class", "btn");
             tagHelperOutput.Attributes.Add(expectedAttribute);
 
@@ -273,8 +263,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             // Arrange
             var tagHelperOutput = new TagHelperOutput(
                 "p",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             var expectedOutputAttribute = new KeyValuePair<string, string>("class", "btn");
             tagHelperOutput.Attributes.Add(expectedOutputAttribute);
 

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

@@ -127,7 +127,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             {
                 { "class", "form-control" },
             };
-            var output = new TagHelperOutput(expectedTagName, htmlAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, htmlAttributes)
             {
                 SelfClosing = true,
             };
@@ -185,7 +185,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                     tagHelperContent.SetContent("Something");
                     return Task.FromResult<TagHelperContent>(tagHelperContent);
                 });
-            var output = new TagHelperOutput(expectedTagName, expectedAttributes, new HtmlEncoder())
+            var output = new TagHelperOutput(expectedTagName, expectedAttributes)
             {
                 SelfClosing = true,
             };

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

@@ -52,8 +52,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 attributes: new Dictionary<string, string>
                 {
                     { "id", "myvalidationmessage" }
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent(expectedPostContent);
@@ -106,8 +105,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 });
             var output = new TagHelperOutput(
                 "span",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent(expectedPostContent);
@@ -147,8 +145,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             };
             var output = new TagHelperOutput(
                 "span",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.Content.SetContent(outputContent);
 
             var context = new TagHelperContext(
@@ -207,8 +204,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             };
             var output = new TagHelperOutput(
                 "span",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
 
             var context = new TagHelperContext(
                 allAttributes: new Dictionary<string, object>(),
@@ -263,8 +259,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var expectedPostContent = "original post-content";
             var output = new TagHelperOutput(
                 "span",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent(expectedPostContent);

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

@@ -58,8 +58,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
                 attributes: new Dictionary<string, string>
                 {
                     { "class", "form-control" }
-                },
+                });
-                htmlEncoder: new HtmlEncoder());
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent("Custom Content");
@@ -103,8 +102,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var expectedPostContent = "original post-content";
             var output = new TagHelperOutput(
                 "div",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent(expectedPostContent);
@@ -146,8 +144,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var expectedContent = "original content";
             var output = new TagHelperOutput(
                 "div",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent("Content of validation summary");
@@ -204,8 +201,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var expectedPostContent = "original post-content";
             var output = new TagHelperOutput(
                 "div",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent(expectedPostContent);
@@ -240,8 +236,7 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
             var expectedContent = "original content";
             var output = new TagHelperOutput(
                 "div",
-                attributes: new Dictionary<string, string>(),
+                attributes: new Dictionary<string, string>());
-                htmlEncoder: new HtmlEncoder());
             output.PreContent.SetContent(expectedPreContent);
             output.Content.SetContent(expectedContent);
             output.PostContent.SetContent("Content of validation message");