Update `TagHelperDirectiveSpanVisitor` to properly capture TagHelper directive text.

- Added a test with optional quotes for each of the `TagHelperDirectiveDescriptor`s, add, remove and prefix.

#744

src/Microsoft.AspNetCore.Razor/Chunks/Generators/AddTagHelperChunkGenerator.cs

@@ -12,8 +12,6 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
     /// </summary>
     public class AddTagHelperChunkGenerator : SpanChunkGenerator
     {
-        private readonly string _lookupText;
-
         /// <summary>
         /// Initializes a new instance of <see cref="AddTagHelperChunkGenerator"/>.
         /// </summary>
@@ -22,9 +20,14 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         /// </param>
         public AddTagHelperChunkGenerator(string lookupText)
         {
-            _lookupText = lookupText;
+            LookupText = lookupText;
         }
 
+        /// <summary>
+        /// Gets the text used to look up <see cref="Compilation.TagHelpers.TagHelperDescriptor"/>s that should be added.
+        /// </summary>
+        public string LookupText { get; }
+
         /// <summary>
         /// Generates <see cref="AddTagHelperChunk"/>s.
         /// </summary>
@@ -35,7 +38,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         /// the current chunk generation process.</param>
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
-            context.ChunkTreeBuilder.AddAddTagHelperChunk(_lookupText, target);
+            context.ChunkTreeBuilder.AddAddTagHelperChunk(LookupText, target);
         }
 
         /// <inheritdoc />
@@ -43,7 +46,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         {
             var other = obj as AddTagHelperChunkGenerator;
             return base.Equals(other) &&
-                string.Equals(_lookupText, other._lookupText, StringComparison.Ordinal);
+                string.Equals(LookupText, other.LookupText, StringComparison.Ordinal);
         }
 
         /// <inheritdoc />
@@ -51,7 +54,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         {
             var combiner = HashCodeCombiner.Start();
             combiner.Add(base.GetHashCode());
-            combiner.Add(_lookupText, StringComparer.Ordinal);
+            combiner.Add(LookupText, StringComparer.Ordinal);
 
             return combiner.CombinedHash;
         }

src/Microsoft.AspNetCore.Razor/Chunks/Generators/RemoveTagHelperChunkGenerator.cs

@@ -12,8 +12,6 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
     /// </summary>
     public class RemoveTagHelperChunkGenerator : SpanChunkGenerator
     {
-        private readonly string _lookupText;
-
         /// <summary>
         /// Initializes a new instance of <see cref="RemoveTagHelperChunkGenerator"/>.
         /// </summary>
@@ -22,9 +20,14 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         /// </param>
         public RemoveTagHelperChunkGenerator(string lookupText)
         {
-            _lookupText = lookupText;
+            LookupText = lookupText;
         }
 
+        /// <summary>
+        /// Text used to look up <see cref="Compilation.TagHelpers.TagHelperDescriptor"/>s that should be removed.
+        /// </summary>
+        public string LookupText { get; }
+
         /// <summary>
         /// Generates <see cref="RemoveTagHelperChunk"/>s.
         /// </summary>
@@ -35,7 +38,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         /// the current chunk generation process.</param>
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
-            context.ChunkTreeBuilder.AddRemoveTagHelperChunk(_lookupText, target);
+            context.ChunkTreeBuilder.AddRemoveTagHelperChunk(LookupText, target);
         }
 
         /// <inheritdoc />
@@ -43,7 +46,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         {
             var other = obj as RemoveTagHelperChunkGenerator;
             return base.Equals(other) &&
-                string.Equals(_lookupText, other._lookupText, StringComparison.Ordinal);
+                string.Equals(LookupText, other.LookupText, StringComparison.Ordinal);
         }
 
         /// <inheritdoc />
@@ -51,7 +54,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         {
             var combiner = HashCodeCombiner.Start();
             combiner.Add(base.GetHashCode());
-            combiner.Add(_lookupText, StringComparer.Ordinal);
+            combiner.Add(LookupText, StringComparer.Ordinal);
 
             return combiner.CombinedHash;
         }

src/Microsoft.AspNetCore.Razor/Chunks/Generators/TagHelperPrefixDirectiveChunkGenerator.cs

@@ -13,8 +13,6 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
     /// </summary>
     public class TagHelperPrefixDirectiveChunkGenerator : SpanChunkGenerator
     {
-        private readonly string _prefix;
-
         /// <summary>
         /// Initializes a new instance of <see cref="TagHelperPrefixDirectiveChunkGenerator"/>.
         /// </summary>
@@ -23,9 +21,14 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         /// </param>
         public TagHelperPrefixDirectiveChunkGenerator(string prefix)
         {
-            _prefix = prefix;
+            Prefix = prefix;
         }
 
+        /// <summary>
+        /// Text used as a required prefix when matching HTML.
+        /// </summary>
+        public string Prefix { get; }
+
         /// <summary>
         /// Generates <see cref="TagHelperPrefixDirectiveChunk"/>s.
         /// </summary>
@@ -36,7 +39,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         /// the current chunk generation process.</param>
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
-            context.ChunkTreeBuilder.AddTagHelperPrefixDirectiveChunk(_prefix, target);
+            context.ChunkTreeBuilder.AddTagHelperPrefixDirectiveChunk(Prefix, target);
         }
 
         /// <inheritdoc />
@@ -44,7 +47,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         {
             var other = obj as TagHelperPrefixDirectiveChunkGenerator;
             return base.Equals(other) &&
-                string.Equals(_prefix, other._prefix, StringComparison.Ordinal);
+                string.Equals(Prefix, other.Prefix, StringComparison.Ordinal);
         }
 
         /// <inheritdoc />
@@ -52,7 +55,7 @@ namespace Microsoft.AspNetCore.Razor.Chunks.Generators
         {
             var combiner = HashCodeCombiner.Start();
             combiner.Add(base.GetHashCode());
-            combiner.Add(_prefix, StringComparer.Ordinal);
+            combiner.Add(Prefix, StringComparer.Ordinal);
 
             return combiner.CombinedHash;
         }

src/Microsoft.AspNetCore.Razor/Parser/TagHelpers/TagHelperDirectiveSpanVisitor.cs

@@ -87,18 +87,27 @@ namespace Microsoft.AspNetCore.Razor.Parser.TagHelpers
                 throw new ArgumentNullException(nameof(span));
             }
 
+            string directiveText;
             TagHelperDirectiveType directiveType;
-            if (span.ChunkGenerator is AddTagHelperChunkGenerator)
+
+            var addTagHelperChunkGenerator = span.ChunkGenerator as AddTagHelperChunkGenerator;
+            var removeTagHelperChunkGenerator = span.ChunkGenerator as RemoveTagHelperChunkGenerator;
+            var tagHelperPrefixChunkGenerator = span.ChunkGenerator as TagHelperPrefixDirectiveChunkGenerator;
+
+            if (addTagHelperChunkGenerator != null)
             {
                 directiveType = TagHelperDirectiveType.AddTagHelper;
+                directiveText = addTagHelperChunkGenerator.LookupText;
             }
-            else if (span.ChunkGenerator is RemoveTagHelperChunkGenerator)
+            else if (removeTagHelperChunkGenerator != null)
             {
                 directiveType = TagHelperDirectiveType.RemoveTagHelper;
+                directiveText = removeTagHelperChunkGenerator.LookupText;
             }
-            else if (span.ChunkGenerator is TagHelperPrefixDirectiveChunkGenerator)
+            else if (tagHelperPrefixChunkGenerator != null)
             {
                 directiveType = TagHelperDirectiveType.TagHelperPrefix;
+                directiveText = tagHelperPrefixChunkGenerator.Prefix;
             }
             else
             {
@@ -106,7 +115,7 @@ namespace Microsoft.AspNetCore.Razor.Parser.TagHelpers
                 return;
             }
 
-            var directiveText = span.Content.Trim();
+            directiveText = directiveText.Trim();
             var startOffset = span.Content.IndexOf(directiveText, StringComparison.Ordinal);
             var offsetContent = span.Content.Substring(0, startOffset);
             var offsetTextLocation = SourceLocation.Advance(span.Start, offsetContent);

test/Microsoft.AspNetCore.Razor.Test/TagHelpers/TagHelperDirectiveSpanVisitorTest.cs

@@ -8,6 +8,7 @@ using Microsoft.AspNetCore.Razor.Parser;
 using Microsoft.AspNetCore.Razor.Parser.SyntaxTree;
 using Microsoft.AspNetCore.Razor.Parser.TagHelpers;
 using Microsoft.AspNetCore.Razor.Test.Framework;
+using Microsoft.AspNetCore.Razor.Tokenizer;
 using Microsoft.Extensions.Internal;
 using Moq;
 using Xunit;
@@ -18,6 +19,109 @@ namespace Microsoft.AspNetCore.Razor.Compilation.TagHelpers
     {
         private static readonly SpanFactory Factory = SpanFactory.CreateCsHtml();
 
+        public static TheoryData QuotedTagHelperDirectivesData
+        {
+            get
+            {
+                var factory = new SpanFactory
+                {
+                    MarkupTokenizerFactory = doc => new HtmlTokenizer(doc),
+                    CodeTokenizerFactory = doc => new CSharpTokenizer(doc),
+                };
+
+                // document, expectedDescriptors
+                return new TheoryData<MarkupBlock, IEnumerable<TagHelperDirectiveDescriptor>>
+                {
+                    {
+                        new MarkupBlock(factory.Code("\"*, someAssembly\"").AsAddTagHelper("*, someAssembly")),
+                        new[]
+                        {
+                            new TagHelperDirectiveDescriptor
+                            {
+                                DirectiveText = "*, someAssembly",
+                                DirectiveType = TagHelperDirectiveType.AddTagHelper
+                            },
+                        }
+                    },
+                    {
+                        new MarkupBlock(factory.Code("\"*, someAssembly\"").AsRemoveTagHelper("*, someAssembly")),
+                        new[]
+                        {
+                            new TagHelperDirectiveDescriptor
+                            {
+                                DirectiveText = "*, someAssembly",
+                                DirectiveType = TagHelperDirectiveType.RemoveTagHelper
+                            },
+                        }
+                    },
+                    {
+                        new MarkupBlock(factory.Code("\"th:\"").AsTagHelperPrefixDirective("th:")),
+                        new[]
+                        {
+                            new TagHelperDirectiveDescriptor
+                            {
+                                DirectiveText = "th:",
+                                DirectiveType = TagHelperDirectiveType.TagHelperPrefix
+                            },
+                        }
+                    },
+                    {
+                        new MarkupBlock(factory.Code("   \"*, someAssembly  \"  ").AsAddTagHelper("*, someAssembly  ")),
+                        new[]
+                        {
+                            new TagHelperDirectiveDescriptor
+                            {
+                                DirectiveText = "*, someAssembly",
+                                DirectiveType = TagHelperDirectiveType.AddTagHelper
+                            },
+                        }
+                    },
+                    {
+                        new MarkupBlock(factory.Code("   \"*, someAssembly  \"  ").AsRemoveTagHelper("*, someAssembly  ")),
+                        new[]
+                        {
+                            new TagHelperDirectiveDescriptor
+                            {
+                                DirectiveText = "*, someAssembly",
+                                DirectiveType = TagHelperDirectiveType.RemoveTagHelper
+                            },
+                        }
+                    },
+                    {
+                        new MarkupBlock(factory.Code("   \"  th  :\"").AsTagHelperPrefixDirective(" th  :")),
+                        new[]
+                        {
+                            new TagHelperDirectiveDescriptor
+                            {
+                                DirectiveText = "th  :",
+                                DirectiveType = TagHelperDirectiveType.TagHelperPrefix
+                            },
+                        }
+                    },
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(QuotedTagHelperDirectivesData))]
+        public void GetDescriptors_LocatesQuotedTagHelperDirectives_CreatesDirectiveDescriptors(
+            MarkupBlock document,
+            IEnumerable<TagHelperDirectiveDescriptor> expectedDescriptors)
+        {
+            // Arrange
+            var resolver = new TestTagHelperDescriptorResolver();
+            var tagHelperDirectiveSpanVisitor = new TagHelperDirectiveSpanVisitor(resolver, new ErrorSink());
+
+            // Act
+            tagHelperDirectiveSpanVisitor.GetDescriptors(document);
+
+            // Assert
+            Assert.Equal(
+                expectedDescriptors,
+                resolver.DirectiveDescriptors,
+                TagHelperDirectiveDescriptorComparer.Default);
+        }
+
         [Fact]
         public void GetDescriptors_InvokesResolveOnceForAllDirectives()
         {