Fixes for excerpt service

We had a bug where were not returning the correct span for highlighting.
Fixed this.

Also we have a problem here, we're using types in our tests that are
coming from Roslyn - however we're not getting IVT for our test
assemblies. So some additional pain is required.

src/Microsoft.CodeAnalysis.Razor.Workspaces/RazorDocumentExcerptService.cs

@@ -37,6 +37,16 @@ namespace Microsoft.CodeAnalysis.Razor
             ExcerptMode mode,
             CancellationToken cancellationToken)
         {
+            var result = await TryGetExcerptInternalAsync(document, span, (ExcerptModeInternal)mode, cancellationToken).ConfigureAwait(false);
+            return result?.ToExcerptResult();
+        }
+
+        public async Task<ExcerptResultInternal?> TryGetExcerptInternalAsync(
+            Document document,
+            TextSpan span,
+            ExcerptModeInternal mode,
+            CancellationToken cancellationToken)
+        { 
             if (_document == null)
             {
                 return null;
@@ -78,7 +88,8 @@ namespace Microsoft.CodeAnalysis.Razor
             // Now translate everything to be relative to the excerpt
             var offset = 0 - excerptSpan.Start;
             var excerptText = primaryText.GetSubText(excerptSpan);
-            excerptSpan = new TextSpan(excerptSpan.Start + offset, excerptSpan.Length);
+            excerptSpan = new TextSpan(0, excerptSpan.Length);
+            primarySpan = new TextSpan(primarySpan.Start + offset, primarySpan.Length);
 
             for (var i = 0; i < classifiedSpans.Count; i++)
             {
@@ -89,24 +100,26 @@ namespace Microsoft.CodeAnalysis.Razor
                 classifiedSpans[i] = new ClassifiedSpan(classifiedSpan.ClassificationType, updated);
             }
 
-            return new ExcerptResult(excerptText, excerptSpan, classifiedSpans.ToImmutable(), document, span);
+            return new ExcerptResultInternal(excerptText, primarySpan, classifiedSpans.ToImmutable(), document, span);
         }
-
+        
-        private TextSpan ChooseExcerptSpan(SourceText primaryText, TextSpan primarySpan, ExcerptMode mode)
+        private TextSpan ChooseExcerptSpan(SourceText primaryText, TextSpan primarySpan, ExcerptModeInternal mode)
         {
             var startLine = primaryText.Lines.GetLineFromPosition(primarySpan.Start);
             var endLine = primaryText.Lines.GetLineFromPosition(primarySpan.End);
 
-            // If we're showing a single line then this will do. Otherwise expand the range by 1 in
+            // If we're showing a single line then this will do. Otherwise expand the range by 3 in
             // each direction (if possible).
-            if (mode == ExcerptMode.Tooltip && startLine.LineNumber > 0)
+            if (mode == ExcerptModeInternal.Tooltip)
             {
-                startLine = primaryText.Lines[startLine.LineNumber - 1];
+                var index = Math.Max(startLine.LineNumber - 3, 0);
+                startLine = primaryText.Lines[index];
             }
 
-            if (mode == ExcerptMode.Tooltip && endLine.LineNumber < primaryText.Lines.Count - 1)
+            if (mode == ExcerptModeInternal.Tooltip)
             {
-                endLine = primaryText.Lines[endLine.LineNumber + 1];
+                var index = Math.Min(endLine.LineNumber + 3, primaryText.Lines.Count - 1);
+                endLine = primaryText.Lines[index];
             }
 
             return new TextSpan(startLine.Start, endLine.End - startLine.Start);
@@ -188,5 +201,45 @@ namespace Microsoft.CodeAnalysis.Razor
 
             return builder;
         }
+
+        // We have IVT access to the Roslyn APIs for product code, but not for testing.
+        public enum ExcerptModeInternal
+        {
+            SingleLine = ExcerptMode.SingleLine,
+            Tooltip = ExcerptMode.Tooltip,
+        }
+
+        // We have IVT access to the Roslyn APIs for product code, but not for testing.
+        public readonly struct ExcerptResultInternal
+        {
+            public readonly SourceText Content;
+
+            public readonly TextSpan MappedSpan;
+
+            public readonly ImmutableArray<ClassifiedSpan> ClassifiedSpans;
+
+            public readonly Document Document;
+
+            public readonly TextSpan Span;
+
+            public ExcerptResultInternal(
+                SourceText content,
+                TextSpan mappedSpan,
+                ImmutableArray<ClassifiedSpan> classifiedSpans,
+                Document document,
+                TextSpan span)
+            {
+                Content = content;
+                MappedSpan = mappedSpan;
+                ClassifiedSpans = classifiedSpans;
+                Document = document;
+                Span = span;
+            }
+
+            public ExcerptResult ToExcerptResult()
+            {
+                return new ExcerptResult(Content, MappedSpan, ClassifiedSpans, Document, Span);
+            }
+        }
     }
 }

test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/RazorExcerptServiceTest.cs

@@ -13,6 +13,7 @@ using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Text;
 using Xunit;
+using static Microsoft.CodeAnalysis.Razor.RazorDocumentExcerptService;
 
 namespace Microsoft.CodeAnalysis.Razor
 {
@@ -33,7 +34,7 @@ namespace Microsoft.CodeAnalysis.Razor
         }
 
         [Fact]
-        public async Task TryExcerptAsync_SingleLine_CanClassifyCSharp()
+        public async Task TryGetExcerptInternalAsync_SingleLine_CanClassifyCSharp()
         {
             // Arrange
             var (sourceText, primarySpan) = CreateText(
@@ -53,13 +54,19 @@ namespace Microsoft.CodeAnalysis.Razor
             var secondarySpan = await GetSecondarySpanAsync(primary, primarySpan, secondary);
             
             // Act
-            var result = await service.TryExcerptAsync(secondary, secondarySpan, ExcerptMode.SingleLine, CancellationToken.None);
+            var result = await service.TryGetExcerptInternalAsync(secondary, secondarySpan, ExcerptModeInternal.SingleLine, CancellationToken.None);
 
             // Assert
             Assert.NotNull(result);
             Assert.Equal(secondarySpan, result.Value.Span);
             Assert.Same(secondary, result.Value.Document);
 
+            // Verifies that the right part of the primary document will be highlighted.
+            Assert.Equal(
+                (await secondary.GetTextAsync()).GetSubText(secondarySpan).ToString(),
+                result.Value.Content.GetSubText(result.Value.MappedSpan).ToString(),
+                ignoreLineEndingDifferences: true);
+
             Assert.Equal(@"    var foo = ""Hello, World!"";", result.Value.Content.ToString(), ignoreLineEndingDifferences: true);
             Assert.Collection(
                 result.Value.ClassifiedSpans,
@@ -91,7 +98,7 @@ namespace Microsoft.CodeAnalysis.Razor
         }
 
         [Fact]
-        public async Task TryExcerptAsync_SingleLine_CanClassifyCSharp_ImplicitExpression()
+        public async Task TryGetExcerptInternalAsync_SingleLine_CanClassifyCSharp_ImplicitExpression()
         {
             // Arrange
             var (sourceText, primarySpan) = CreateText(
@@ -111,13 +118,19 @@ namespace Microsoft.CodeAnalysis.Razor
             var secondarySpan = await GetSecondarySpanAsync(primary, primarySpan, secondary);
 
             // Act
-            var result = await service.TryExcerptAsync(secondary, secondarySpan, ExcerptMode.SingleLine, CancellationToken.None);
+            var result = await service.TryGetExcerptInternalAsync(secondary, secondarySpan, ExcerptModeInternal.SingleLine, CancellationToken.None);
 
             // Assert
             Assert.NotNull(result);
             Assert.Equal(secondarySpan, result.Value.Span);
             Assert.Same(secondary, result.Value.Document);
 
+            // Verifies that the right part of the primary document will be highlighted.
+            Assert.Equal(
+                (await secondary.GetTextAsync()).GetSubText(secondarySpan).ToString(),
+                result.Value.Content.GetSubText(result.Value.MappedSpan).ToString(),
+                ignoreLineEndingDifferences: true);
+
             Assert.Equal(@"  <body>@foo</body>", result.Value.Content.ToString(), ignoreLineEndingDifferences: true);
             Assert.Collection(
                 result.Value.ClassifiedSpans,
@@ -139,7 +152,7 @@ namespace Microsoft.CodeAnalysis.Razor
         }
 
         [Fact]
-        public async Task TryExcerptAsync_SingleLine_CanClassifyCSharp_ComplexLine()
+        public async Task TryGetExcerptInternalAsync_SingleLine_CanClassifyCSharp_ComplexLine()
         {
             // Arrange
             var (sourceText, primarySpan) = CreateText(
@@ -159,13 +172,19 @@ namespace Microsoft.CodeAnalysis.Razor
             var secondarySpan = await GetSecondarySpanAsync(primary, primarySpan, secondary);
 
             // Act
-            var result = await service.TryExcerptAsync(secondary, secondarySpan, ExcerptMode.SingleLine, CancellationToken.None);
+            var result = await service.TryGetExcerptInternalAsync(secondary, secondarySpan, ExcerptModeInternal.SingleLine, CancellationToken.None);
 
             // Assert
             Assert.NotNull(result);
             Assert.Equal(secondarySpan, result.Value.Span);
             Assert.Same(secondary, result.Value.Document);
 
+            // Verifies that the right part of the primary document will be highlighted.
+            Assert.Equal(
+                (await secondary.GetTextAsync()).GetSubText(secondarySpan).ToString(),
+                result.Value.Content.GetSubText(result.Value.MappedSpan).ToString(),
+                ignoreLineEndingDifferences: true);
+
             Assert.Equal(@"  <div>@(3 + 4)</div><div>@(foo + foo)</div>", result.Value.Content.ToString(), ignoreLineEndingDifferences: true);
             Assert.Collection(
                 result.Value.ClassifiedSpans,
@@ -217,7 +236,7 @@ namespace Microsoft.CodeAnalysis.Razor
         }
 
         [Fact]
-        public async Task TryExcerptAsync_MultiLine_CanClassifyCSharp()
+        public async Task TryGetExcerptInternalAsync_MultiLine_CanClassifyCSharp()
         {
             // Arrange
             var (sourceText, primarySpan) = CreateText(
@@ -226,8 +245,8 @@ namespace Microsoft.CodeAnalysis.Razor
 @{
     var |foo| = ""Hello, World!"";
 }
-  <body>@foo</body>
+  <body></body>
-  <div>@(3 + 4)</div><div>@(foo + foo)</div>
+  <div></div>
 </html>
 ");
 
@@ -237,17 +256,27 @@ namespace Microsoft.CodeAnalysis.Razor
             var secondarySpan = await GetSecondarySpanAsync(primary, primarySpan, secondary);
 
             // Act
-            var result = await service.TryExcerptAsync(secondary, secondarySpan, ExcerptMode.Tooltip, CancellationToken.None);
+            var result = await service.TryGetExcerptInternalAsync(secondary, secondarySpan, ExcerptModeInternal.Tooltip, CancellationToken.None);
 
             // Assert
             Assert.NotNull(result);
             Assert.Equal(secondarySpan, result.Value.Span);
             Assert.Same(secondary, result.Value.Document);
 
+            // Verifies that the right part of the primary document will be highlighted.
             Assert.Equal(
-@"@{
+                (await secondary.GetTextAsync()).GetSubText(secondarySpan).ToString(),
+                result.Value.Content.GetSubText(result.Value.MappedSpan).ToString(),
+                ignoreLineEndingDifferences: true);
+
+            Assert.Equal(
+@"
+<html>
+@{
     var foo = ""Hello, World!"";
-}", 
+}
+  <body></body>
+  <div></div>", 
                 result.Value.Content.ToString(), ignoreLineEndingDifferences: true);
 
             Assert.Collection(
@@ -255,7 +284,12 @@ namespace Microsoft.CodeAnalysis.Razor
                 c =>
                 {
                     Assert.Equal(ClassificationTypeNames.Text, c.ClassificationType);
-                    Assert.Equal("@{", result.Value.Content.GetSubText(c.TextSpan).ToString());
+                    Assert.Equal(
+@"
+<html>
+@{", 
+                            result.Value.Content.GetSubText(c.TextSpan).ToString(),
+                            ignoreLineEndingDifferences: true);
                 },
                 c =>
                 {
@@ -285,12 +319,17 @@ namespace Microsoft.CodeAnalysis.Razor
                 c =>
                 {
                     Assert.Equal(ClassificationTypeNames.Text, c.ClassificationType);
-                    Assert.Equal("}", result.Value.Content.GetSubText(c.TextSpan).ToString());
+                    Assert.Equal(
+@"}
+  <body></body>
+  <div></div>", 
+                        result.Value.Content.GetSubText(c.TextSpan).ToString(), 
+                        ignoreLineEndingDifferences: true);
                 });
         }
 
         [Fact]
-        public async Task TryExcerptAsync_MultiLine_Boundaries_CanClassifyCSharp()
+        public async Task TryGetExcerptInternalAsync_MultiLine_Boundaries_CanClassifyCSharp()
         {
             // Arrange
             var (sourceText, primarySpan) = CreateText(@"@{ var |foo| = ""Hello, World!""; }");
@@ -301,13 +340,19 @@ namespace Microsoft.CodeAnalysis.Razor
             var secondarySpan = await GetSecondarySpanAsync(primary, primarySpan, secondary);
 
             // Act
-            var result = await service.TryExcerptAsync(secondary, secondarySpan, ExcerptMode.Tooltip, CancellationToken.None);
+            var result = await service.TryGetExcerptInternalAsync(secondary, secondarySpan, ExcerptModeInternal.Tooltip, CancellationToken.None);
 
             // Assert
             Assert.NotNull(result);
             Assert.Equal(secondarySpan, result.Value.Span);
             Assert.Same(secondary, result.Value.Document);
 
+            // Verifies that the right part of the primary document will be highlighted.
+            Assert.Equal(
+                (await secondary.GetTextAsync()).GetSubText(secondarySpan).ToString(),
+                result.Value.Content.GetSubText(result.Value.MappedSpan).ToString(),
+                ignoreLineEndingDifferences: true);
+
             Assert.Equal(
 @"@{ var foo = ""Hello, World!""; }",
                 result.Value.Content.ToString(), ignoreLineEndingDifferences: true);