First step in converting parser tests to use baselines

- Added the necessary infrastructure to serialize and verify the syntax
tree
- Updated ParserVisitor to be overrideable
- Made CSharpVerbatimBlockTest to use baselines

src/Microsoft.AspNetCore.Razor.Language/Legacy/ParentChunkGenerator.cs

@@ -47,10 +47,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
 
             public void Accept(ParserVisitor visitor, Block block)
             {
-                for (var i = 0; i < block.Children.Count; i++)
+                visitor.VisitDefault(block);
-                {
-                    block.Children[i].Accept(visitor);
-                }
             }
         }
     }

src/Microsoft.AspNetCore.Razor.Language/Legacy/ParserVisitor.cs

@@ -5,7 +5,12 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
 {
     internal abstract class ParserVisitor
     {
-        protected virtual void VisitDefault(Block block)
+        public virtual void Visit(SyntaxTreeNode node)
+        {
+            node.Accept(this);
+        }
+
+        public virtual void VisitDefault(Block block)
         {
             for (var i = 0; i < block.Children.Count; i++)
             {
@@ -13,6 +18,10 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             }
         }
 
+        public virtual void VisitDefault(Span span)
+        {
+        }
+
         public virtual void VisitBlock(Block block)
         {
             if (block.ChunkGenerator != null)
@@ -44,35 +53,6 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             VisitDefault(block);
         }
 
-        public virtual void VisitExpressionSpan(ExpressionChunkGenerator chunkGenerator, Span span)
-        {
-        }
-
-        public virtual void VisitMarkupSpan(MarkupChunkGenerator chunkGenerator, Span span)
-        {
-        }
-
-        public virtual void VisitImportSpan(AddImportChunkGenerator chunkGenerator, Span span)
-        {
-        }
-
-        public virtual void VisitStatementSpan(StatementChunkGenerator chunkGenerator, Span span)
-        {
-        }
-
-        public virtual void VisitLiteralAttributeSpan(LiteralAttributeChunkGenerator chunkGenerator, Span span)
-        {
-        }
-
-        public virtual void VisitDirectiveToken(DirectiveTokenChunkGenerator chunkGenerator, Span block)
-        {
-        }
-
-        public virtual void VisitDirectiveBlock(DirectiveChunkGenerator chunkGenerator, Block block)
-        {
-            VisitDefault(block);
-        }
-
         public virtual void VisitTemplateBlock(TemplateBlockChunkGenerator chunkGenerator, Block block)
         {
             VisitDefault(block);
@@ -88,16 +68,54 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             VisitDefault(block);
         }
 
+        public virtual void VisitDirectiveBlock(DirectiveChunkGenerator chunkGenerator, Block block)
+        {
+            VisitDefault(block);
+        }
+
+        public virtual void VisitExpressionSpan(ExpressionChunkGenerator chunkGenerator, Span span)
+        {
+            VisitDefault(span);
+        }
+
+        public virtual void VisitMarkupSpan(MarkupChunkGenerator chunkGenerator, Span span)
+        {
+            VisitDefault(span);
+        }
+
+        public virtual void VisitImportSpan(AddImportChunkGenerator chunkGenerator, Span span)
+        {
+            VisitDefault(span);
+        }
+
+        public virtual void VisitStatementSpan(StatementChunkGenerator chunkGenerator, Span span)
+        {
+            VisitDefault(span);
+        }
+
+        public virtual void VisitLiteralAttributeSpan(LiteralAttributeChunkGenerator chunkGenerator, Span span)
+        {
+            VisitDefault(span);
+        }
+
+        public virtual void VisitDirectiveToken(DirectiveTokenChunkGenerator chunkGenerator, Span span)
+        {
+            VisitDefault(span);
+        }
+
         public virtual void VisitAddTagHelperSpan(AddTagHelperChunkGenerator chunkGenerator, Span span)
         {
+            VisitDefault(span);
         }
 
         public virtual void VisitRemoveTagHelperSpan(RemoveTagHelperChunkGenerator chunkGenerator, Span span)
         {
+            VisitDefault(span);
         }
 
         public virtual void VisitTagHelperPrefixDirectiveSpan(TagHelperPrefixDirectiveChunkGenerator chunkGenerator, Span span)
         {
+            VisitDefault(span);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Legacy/SpanChunkGenerator.cs

@@ -32,6 +32,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
         {
             public void Accept(ParserVisitor visitor, Span span)
             {
+                visitor.VisitDefault(span);
             }
 
             public void GenerateChunk(Span target, ChunkGeneratorContext context)

test/Microsoft.AspNetCore.Razor.Language.Test/Legacy/CSharpReservedWordsTest.cs

@@ -7,6 +7,11 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
 {
     public class CSharpReservedWordsTest : CsHtmlCodeParserTestBase
     {
+        public CSharpReservedWordsTest()
+        {
+            UseBaselineTests = true;
+        }
+
         [Theory]
         [InlineData("namespace")]
         [InlineData("class")]

test/Microsoft.AspNetCore.Razor.Language.Test/Legacy/CSharpVerbatimBlockTest.cs

@@ -10,125 +10,45 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
     {
         private const string TestExtraKeyword = "model";
 
+        public CSharpVerbatimBlockTest()
+        {
+            UseBaselineTests = true;
+        }
+
         [Fact]
         public void VerbatimBlock()
         {
-            ParseBlockTest("@{ foo(); }",
+            ParseBlockTest("@{ foo(); }");
-                           new StatementBlock(
-                               Factory.CodeTransition(),
-                               Factory.MetaCode("{")
-                                   .Accepts(AcceptedCharactersInternal.None),
-                               Factory.Code(" foo(); ")
-                                   .AsStatement()
-                                   .AutoCompleteWith(autoCompleteString: null),
-                               Factory.MetaCode("}")
-                                   .Accepts(AcceptedCharactersInternal.None)
-                               ));
         }
 
         [Fact]
         public void InnerImplicitExpressionWithOnlySingleAtOutputsZeroLengthCodeSpan()
         {
-            ParseBlockTest("{@}",
+            ParseBlockTest("{@}");
-                           new StatementBlock(
-                               Factory.MetaCode("{").Accepts(AcceptedCharactersInternal.None),
-                               Factory.EmptyCSharp()
-                                   .AsStatement()
-                                   .AutoCompleteWith(autoCompleteString: null),
-                               new ExpressionBlock(
-                                   Factory.CodeTransition(),
-                                   Factory.EmptyCSharp().AsImplicitExpression(KeywordSet, acceptTrailingDot: true).Accepts(AcceptedCharactersInternal.NonWhiteSpace)
-                                   ),
-                               Factory.EmptyCSharp().AsStatement(),
-                               Factory.MetaCode("}").Accepts(AcceptedCharactersInternal.None)),
-                           designTime: true,
-                           expectedErrors: new[]
-                           {
-                               RazorDiagnosticFactory.CreateParsing_UnexpectedCharacterAtStartOfCodeBlock(
-                                new SourceSpan(new SourceLocation(2, 0, 2), contentLength: 1),
-                                "}")
-                           });
         }
 
         [Fact]
         public void InnerImplicitExpressionDoesNotAcceptDotAfterAt()
         {
-            ParseBlockTest("{@.}",
+            ParseBlockTest("{@.}");
-                           new StatementBlock(
-                               Factory.MetaCode("{").Accepts(AcceptedCharactersInternal.None),
-                               Factory.EmptyCSharp()
-                                   .AsStatement()
-                                   .AutoCompleteWith(autoCompleteString: null),
-                               new ExpressionBlock(
-                                   Factory.CodeTransition(),
-                                   Factory.EmptyCSharp().AsImplicitExpression(KeywordSet, acceptTrailingDot: true).Accepts(AcceptedCharactersInternal.NonWhiteSpace)
-                                   ),
-                               Factory.Code(".").AsStatement(),
-                               Factory.MetaCode("}").Accepts(AcceptedCharactersInternal.None)),
-                           designTime: true,
-                           expectedErrors: new[]
-                           {
-                               RazorDiagnosticFactory.CreateParsing_UnexpectedCharacterAtStartOfCodeBlock(
-                                   new SourceSpan(new SourceLocation(2, 0, 2), contentLength: 1),
-                                   ".")
-                           });
         }
 
         [Fact]
         public void InnerImplicitExpressionWithOnlySingleAtAcceptsSingleSpaceOrNewlineAtDesignTime()
         {
-            ParseBlockTest("{" + Environment.NewLine
+            ParseBlockTest("{" + Environment.NewLine + "    @" + Environment.NewLine + "}", designTime: true);
-                         + "    @" + Environment.NewLine
-                         + "}",
-                           new StatementBlock(
-                               Factory.MetaCode("{").Accepts(AcceptedCharactersInternal.None),
-                               Factory.Code(Environment.NewLine + "    ")
-                                   .AsStatement()
-                                   .AutoCompleteWith(autoCompleteString: null),
-                               new ExpressionBlock(
-                                   Factory.CodeTransition(),
-                                   Factory.EmptyCSharp().AsImplicitExpression(KeywordSet, acceptTrailingDot: true).Accepts(AcceptedCharactersInternal.NonWhiteSpace)
-                                   ),
-                               Factory.Code(Environment.NewLine).AsStatement(),
-                               Factory.MetaCode("}").Accepts(AcceptedCharactersInternal.None)),
-                /* designTimeParser */ true,
-                           RazorDiagnosticFactory.CreateParsing_UnexpectedWhiteSpaceAtStartOfCodeBlock(
-                                new SourceSpan(new SourceLocation(6 + Environment.NewLine.Length, 1, 5), Environment.NewLine.Length)));
         }
 
         [Fact]
         public void InnerImplicitExpressionDoesNotAcceptTrailingNewlineInRunTimeMode()
         {
-            ParseBlockTest("{@foo." + Environment.NewLine
+            ParseBlockTest("{@foo." + Environment.NewLine + "}");
-                         + "}",
-                           new StatementBlock(
-                               Factory.MetaCode("{").Accepts(AcceptedCharactersInternal.None),
-                               Factory.EmptyCSharp()
-                                   .AsStatement()
-                                   .AutoCompleteWith(autoCompleteString: null),
-                               new ExpressionBlock(
-                                   Factory.CodeTransition(),
-                                   Factory.Code("foo.").AsImplicitExpression(KeywordSet, acceptTrailingDot: true).Accepts(AcceptedCharactersInternal.NonWhiteSpace)),
-                               Factory.Code(Environment.NewLine).AsStatement(),
-                               Factory.MetaCode("}").Accepts(AcceptedCharactersInternal.None)));
         }
 
         [Fact]
         public void InnerImplicitExpressionAcceptsTrailingNewlineInDesignTimeMode()
         {
-            ParseBlockTest("{@foo." + Environment.NewLine
+            ParseBlockTest("{@foo." + Environment.NewLine + "}", designTime: true);
-                         + "}",
-                           new StatementBlock(
-                               Factory.MetaCode("{").Accepts(AcceptedCharactersInternal.None),
-                               Factory.EmptyCSharp()
-                                   .AsStatement()
-                                   .AutoCompleteWith(autoCompleteString: null),
-                               new ExpressionBlock(
-                                   Factory.CodeTransition(),
-                                   Factory.Code("foo.").AsImplicitExpression(KeywordSet, acceptTrailingDot: true).Accepts(AcceptedCharactersInternal.NonWhiteSpace)),
-                               Factory.Code(Environment.NewLine).AsStatement(),
-                               Factory.MetaCode("}").Accepts(AcceptedCharactersInternal.None)),
-                           designTime: true);
         }
     }
 }

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExpressionAcceptsTrailingNewlineInDesignTimeMode.syntaxtree.txt

@@ -0,0 +1,8 @@
+Statement block - NullParentChunkGenerator - 9 - (0:0,0)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - { - (0:0,0)
+    Code span - StatementChunkGenerator - AutoCompleteEditHandler;Accepts:Any,AutoComplete:[<null>];AtEOL -  - (1:0,1)
+    Expression block - ExpressionChunkGenerator - 5 - (1:0,1)
+        Transition span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - @ - (1:0,1)
+        Code span - ExpressionChunkGenerator - ImplicitExpressionEditHandler;Accepts:NonWhiteSpace;ImplicitExpression[ATD];K14 - foo. - (2:0,2)
+    Code span - StatementChunkGenerator - SpanEditHandler;Accepts:Any - LF - (6:0,6)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - } - (8:1,0)

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExpressionDoesNotAcceptDotAfterAt.diagnostics.txt

@@ -0,0 +1 @@
+(1,3): Error RZ1005: "." is not valid at the start of a code block.  Only identifiers, keywords, comments, "(" and "{" are valid.

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExpressionDoesNotAcceptDotAfterAt.syntaxtree.txt

@@ -0,0 +1,8 @@
+Statement block - NullParentChunkGenerator - 4 - (0:0,0)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - { - (0:0,0)
+    Code span - StatementChunkGenerator - AutoCompleteEditHandler;Accepts:Any,AutoComplete:[<null>];AtEOL -  - (1:0,1)
+    Expression block - ExpressionChunkGenerator - 1 - (1:0,1)
+        Transition span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - @ - (1:0,1)
+        Code span - ExpressionChunkGenerator - ImplicitExpressionEditHandler;Accepts:NonWhiteSpace;ImplicitExpression[ATD];K14 -  - (2:0,2)
+    Code span - StatementChunkGenerator - SpanEditHandler;Accepts:Any - . - (2:0,2)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - } - (3:0,3)

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExpressionDoesNotAcceptTrailingNewlineInRunTimeMode.syntaxtree.txt

@@ -0,0 +1,8 @@
+Statement block - NullParentChunkGenerator - 9 - (0:0,0)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - { - (0:0,0)
+    Code span - StatementChunkGenerator - AutoCompleteEditHandler;Accepts:Any,AutoComplete:[<null>];AtEOL -  - (1:0,1)
+    Expression block - ExpressionChunkGenerator - 5 - (1:0,1)
+        Transition span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - @ - (1:0,1)
+        Code span - ExpressionChunkGenerator - ImplicitExpressionEditHandler;Accepts:NonWhiteSpace;ImplicitExpression[ATD];K14 - foo. - (2:0,2)
+    Code span - StatementChunkGenerator - SpanEditHandler;Accepts:Any - LF - (6:0,6)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - } - (8:1,0)

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExpressionWithOnlySingleAtAcceptsSingleSpaceOrNewlineAtDesignTime.diagnostics.txt

@@ -0,0 +1 @@
+(2,6): Error RZ1003: A space or line break was encountered after the "@" character.  Only valid identifiers, keywords, comments, "(" and "{" are valid at the start of a code block and they must occur immediately following "@" with no space in between.

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExpressionWithOnlySingleAtAcceptsSingleSpaceOrNewlineAtDesignTime.syntaxtree.txt

@@ -0,0 +1,8 @@
+Statement block - NullParentChunkGenerator - 11 - (0:0,0)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - { - (0:0,0)
+    Code span - StatementChunkGenerator - AutoCompleteEditHandler;Accepts:Any,AutoComplete:[<null>];AtEOL - LF     - (1:0,1)
+    Expression block - ExpressionChunkGenerator - 1 - (7:1,4)
+        Transition span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - @ - (7:1,4)
+        Code span - ExpressionChunkGenerator - ImplicitExpressionEditHandler;Accepts:NonWhiteSpace;ImplicitExpression[ATD];K14 -  - (8:1,5)
+    Code span - StatementChunkGenerator - SpanEditHandler;Accepts:Any - LF - (8:1,5)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - } - (10:2,0)

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExpressionWithOnlySingleAtOutputsZeroLengthCodeSpan.diagnostics.txt

@@ -0,0 +1 @@
+(1,3): Error RZ1005: "}" is not valid at the start of a code block.  Only identifiers, keywords, comments, "(" and "{" are valid.

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExpressionWithOnlySingleAtOutputsZeroLengthCodeSpan.syntaxtree.txt

@@ -0,0 +1,8 @@
+Statement block - NullParentChunkGenerator - 3 - (0:0,0)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - { - (0:0,0)
+    Code span - StatementChunkGenerator - AutoCompleteEditHandler;Accepts:Any,AutoComplete:[<null>];AtEOL -  - (1:0,1)
+    Expression block - ExpressionChunkGenerator - 1 - (1:0,1)
+        Transition span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - @ - (1:0,1)
+        Code span - ExpressionChunkGenerator - ImplicitExpressionEditHandler;Accepts:NonWhiteSpace;ImplicitExpression[ATD];K14 -  - (2:0,2)
+    Code span - StatementChunkGenerator - SpanEditHandler;Accepts:Any -  - (2:0,2)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - } - (2:0,2)

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/CSharpVerbatimBlockTest/VerbatimBlock.syntaxtree.txt

@@ -0,0 +1,5 @@
+Statement block - NullParentChunkGenerator - 11 - (0:0,0)
+    Transition span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - @ - (0:0,0)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - { - (1:0,1)
+    Code span - StatementChunkGenerator - AutoCompleteEditHandler;Accepts:Any,AutoComplete:[<null>];AtEOL -  foo();  - (2:0,2)
+    MetaCode span - NullSpanChunkGenerator - SpanEditHandler;Accepts:None - } - (10:0,10)

test/Microsoft.AspNetCore.Razor.Test.Common/Language/Legacy/IntializeTestFileAttribute.cs

@@ -0,0 +1,36 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Reflection;
+using Xunit;
+using Xunit.Sdk;
+
+namespace Microsoft.AspNetCore.Razor.Language.Legacy
+{
+    public class IntializeTestFileAttribute : BeforeAfterTestAttribute
+    {
+        public override void Before(MethodInfo methodUnderTest)
+        {
+            if (typeof(ParserTestBase).GetTypeInfo().IsAssignableFrom(methodUnderTest.DeclaringType.GetTypeInfo()))
+            {
+                var typeName = methodUnderTest.DeclaringType.Name;
+                ParserTestBase.FileName = $"TestFiles/ParserTests/{typeName}/{methodUnderTest.Name}";
+                ParserTestBase.IsTheory = false;
+
+                if (methodUnderTest.GetCustomAttributes(typeof(TheoryAttribute), inherit: false).Length > 0)
+                {
+                    ParserTestBase.IsTheory = true;
+                }
+            }
+        }
+
+        public override void After(MethodInfo methodUnderTest)
+        {
+            if (typeof(ParserTestBase).GetTypeInfo().IsAssignableFrom(methodUnderTest.DeclaringType.GetTypeInfo()))
+            {
+                ParserTestBase.FileName = null;
+                ParserTestBase.IsTheory = false;
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Razor.Test.Common/Language/Legacy/ParserTestBase.cs

@@ -4,20 +4,36 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.IO;
 using System.Linq;
+using System.Reflection;
+#if NET46
+using System.Runtime.Remoting;
+using System.Runtime.Remoting.Messaging;
+#else
+using System.Threading;
+#endif
 using System.Text;
 using Xunit;
+using Xunit.Sdk;
 
 namespace Microsoft.AspNetCore.Razor.Language.Legacy
 {
+    [IntializeTestFile]
     public abstract class ParserTestBase
     {
+#if !NET46
+        private static readonly AsyncLocal<string> _fileName = new AsyncLocal<string>();
+        private static readonly AsyncLocal<bool> _isTheory = new AsyncLocal<bool>();
+#endif
+
         internal static Block IgnoreOutput = new IgnoreOutputBlock();
 
         internal ParserTestBase()
         {
             Factory = CreateSpanFactory();
             BlockFactory = CreateBlockFactory();
+            TestProjectRoot = TestProject.GetProjectDirectory(GetType());
         }
 
         /// <summary>
@@ -30,6 +46,105 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
 
         internal BlockFactory BlockFactory { get; private set; }
 
+#if GENERATE_BASELINES
+        protected bool GenerateBaselines { get; set; } = true;
+#else
+        protected bool GenerateBaselines { get; set; } = false;
+#endif
+
+        protected string TestProjectRoot { get; }
+
+        protected bool UseBaselineTests { get; set; }
+
+        // Used by the test framework to set the 'base' name for test files.
+        public static string FileName
+        {
+#if NET46
+            get
+            {
+                var handle = (ObjectHandle)CallContext.LogicalGetData("ParserTestBase_FileName");
+                return (string)handle.Unwrap();
+            }
+            set
+            {
+                CallContext.LogicalSetData("ParserTestBase_FileName", new ObjectHandle(value));
+            }
+#elif NETCOREAPP2_2
+            get { return _fileName.Value; }
+            set { _fileName.Value = value; }
+#endif
+        }
+
+        public static bool IsTheory
+        {
+#if NET46
+            get
+            {
+                var handle = (ObjectHandle)CallContext.LogicalGetData("ParserTestBase_IsTheory");
+                return (bool)handle.Unwrap();
+            }
+            set
+            {
+                CallContext.LogicalSetData("ParserTestBase_IsTheory", new ObjectHandle(value));
+            }
+#elif NETCOREAPP2_2
+            get { return _isTheory.Value; }
+            set { _isTheory.Value = value; }
+#endif
+        }
+
+        internal void AssertSyntaxTreeNodeMatchesBaseline(RazorSyntaxTree syntaxTree)
+        {
+            if (FileName == null)
+            {
+                var message = $"{nameof(AssertSyntaxTreeNodeMatchesBaseline)} should only be called from a parser test ({nameof(FileName)} is null).";
+                throw new InvalidOperationException(message);
+            }
+
+            var baselineFileName = Path.ChangeExtension(FileName, ".syntaxtree.txt");
+            var baselineDiagnosticsFileName = Path.ChangeExtension(FileName, ".diagnostics.txt");
+
+            var root = syntaxTree.Root;
+            var diagnostics = syntaxTree.Diagnostics;
+            if (GenerateBaselines)
+            {
+                var baselineFullPath = Path.Combine(TestProjectRoot, baselineFileName);
+                File.WriteAllText(baselineFullPath, SyntaxTreeNodeSerializer.Serialize(root));
+
+                var baselineDiagnosticsFullPath = Path.Combine(TestProjectRoot, baselineDiagnosticsFileName);
+                var lines = diagnostics.Select(RazorDiagnosticSerializer.Serialize).ToArray();
+                if (lines.Any())
+                {
+                    File.WriteAllLines(baselineDiagnosticsFullPath, lines);
+                }
+                else if (File.Exists(baselineDiagnosticsFullPath))
+                {
+                    File.Delete(baselineDiagnosticsFullPath);
+                }
+
+                return;
+            }
+
+            var stFile = TestFile.Create(baselineFileName, GetType().GetTypeInfo().Assembly);
+            if (!stFile.Exists())
+            {
+                throw new XunitException($"The resource {baselineFileName} was not found.");
+            }
+
+            var baseline = stFile.ReadAllText().Split(new char[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
+            SyntaxTreeNodeVerifier.Verify(root, baseline);
+
+            var baselineDiagnostics = string.Empty;
+            var diagnosticsFile = TestFile.Create(baselineDiagnosticsFileName, GetType().GetTypeInfo().Assembly);
+            if (diagnosticsFile.Exists())
+            {
+                baselineDiagnostics = diagnosticsFile.ReadAllText();
+            }
+
+            var actualDiagnostics = string.Concat(diagnostics.Select(d => RazorDiagnosticSerializer.Serialize(d) + "\r\n"));
+            Assert.Equal(baselineDiagnostics, actualDiagnostics);
+        }
+
         internal RazorSyntaxTree ParseBlock(string document, bool designTime)
         {
             return ParseBlock(RazorLanguageVersion.Latest, document, designTime);
@@ -128,7 +243,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
         {
             directives = directives ?? Array.Empty<DirectiveDescriptor>();
 
-            var source = TestRazorSourceDocument.Create(document, filePath: null);
+            var source = TestRazorSourceDocument.Create(document, filePath: null, normalizeNewLines: UseBaselineTests);
             var options = CreateParserOptions(version, directives, designTime);
             var context = new ParserContext(source, options);
 
@@ -222,6 +337,12 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
         {
             var result = ParseBlock(version, document, directives, designTime);
 
+            if (UseBaselineTests && !IsTheory)
+            {
+                AssertSyntaxTreeNodeMatchesBaseline(result);
+                return;
+            }
+
             if (FixupSpans)
             {
                 SpancestryCorrector.Correct(expected);

test/Microsoft.AspNetCore.Razor.Test.Common/Language/Legacy/SyntaxTreeNodeSerializer.cs

@@ -0,0 +1,48 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.IO;
+
+namespace Microsoft.AspNetCore.Razor.Language.Legacy
+{
+    public static class SyntaxTreeNodeSerializer
+    {
+        internal static string Serialize(SyntaxTreeNode node)
+        {
+            using (var writer = new StringWriter())
+            {
+                var walker = new Walker(writer);
+                walker.Visit(node);
+
+                return writer.ToString();
+            }
+        }
+
+        private class Walker : SyntaxTreeNodeWalker
+        {
+            private readonly SyntaxTreeNodeWriter _visitor;
+            private readonly TextWriter _writer;
+
+            public Walker(TextWriter writer)
+            {
+                _visitor = new SyntaxTreeNodeWriter(writer);
+                _writer = writer;
+            }
+
+            public TextWriter Writer { get; }
+
+            public override void Visit(SyntaxTreeNode node)
+            {
+                _visitor.Visit(node);
+                _writer.WriteLine();
+
+                if (node is Block block)
+                {
+                    _visitor.Depth++;
+                    base.VisitDefault(block);
+                    _visitor.Depth--;
+                }
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Razor.Test.Common/Language/Legacy/SyntaxTreeNodeVerifier.cs

@@ -0,0 +1,276 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using Xunit;
+using Xunit.Sdk;
+
+namespace Microsoft.AspNetCore.Razor.Language.Legacy
+{
+    public static class SyntaxTreeNodeVerifier
+    {
+        internal static void Verify(SyntaxTreeNode node, string[] baseline)
+        {
+            var walker = new Walker(baseline);
+            walker.Visit(node);
+            walker.AssertReachedEndOfBaseline();
+        }
+
+        private class Walker : SyntaxTreeNodeWalker
+        {
+            private readonly string[] _baseline;
+            private readonly SyntaxTreeNodeWriter _visitor;
+            private readonly StringWriter _writer;
+
+            private int _index;
+
+            public Walker(string[] baseline)
+            {
+                _writer = new StringWriter();
+
+                _visitor = new SyntaxTreeNodeWriter(_writer);
+                _baseline = baseline;
+            }
+
+            public TextWriter Writer { get; }
+
+            public override void Visit(SyntaxTreeNode node)
+            {
+                var expected = _index < _baseline.Length ? _baseline[_index++] : null;
+
+                // Write the node as text for comparison
+                _writer.GetStringBuilder().Clear();
+                _visitor.Visit(node);
+                var actual = _writer.GetStringBuilder().ToString();
+
+                AssertNodeEquals(node, Ancestors, expected, actual);
+
+                if (node is Block block)
+                {
+                    _visitor.Depth++;
+                    base.VisitDefault(block);
+                    _visitor.Depth--;
+                }
+            }
+
+            public void AssertReachedEndOfBaseline()
+            {
+                // Since we're walking the nodes of our generated code there's the chance that our baseline is longer.
+                Assert.True(_baseline.Length == _index, "Not all lines of the baseline were visited!");
+            }
+
+            private void AssertNodeEquals(SyntaxTreeNode node, IEnumerable<SyntaxTreeNode> ancestors, string expected, string actual)
+            {
+                if (string.Equals(expected, actual))
+                {
+                    // YAY!!! everything is great.
+                    return;
+                }
+
+                if (expected == null)
+                {
+                    var message = "The node is missing from baseline.";
+                    throw new SyntaxTreeNodeBaselineException(node, Ancestors.ToArray(), expected, actual, message);
+                }
+
+                int charsVerified = 0;
+                AssertNestingEqual(node, ancestors, expected, actual, ref charsVerified);
+                AssertNameEqual(node, ancestors, expected, actual, ref charsVerified);
+                AssertDelimiter(node, expected, actual, true, ref charsVerified);
+                AssertLocationEqual(node, ancestors, expected, actual, ref charsVerified);
+                AssertDelimiter(node, expected, actual, false, ref charsVerified);
+                AssertContentEqual(node, ancestors, expected, actual, ref charsVerified);
+
+                throw new InvalidOperationException("We can't figure out HOW these two things are different. This is a bug.");
+            }
+
+            private void AssertNestingEqual(SyntaxTreeNode node, IEnumerable<SyntaxTreeNode> ancestors, string expected, string actual, ref int charsVerified)
+            {
+                var i = 0;
+                for (; i < expected.Length; i++)
+                {
+                    if (expected[i] != ' ')
+                    {
+                        break;
+                    }
+                }
+
+                var failed = false;
+                var j = 0;
+                for (; j < i; j++)
+                {
+                    if (actual.Length <= j || actual[j] != ' ')
+                    {
+                        failed = true;
+                        break;
+                    }
+                }
+
+                if (actual.Length <= j + 1 || actual[j] == ' ')
+                {
+                    failed = true;
+                }
+
+                if (failed)
+                {
+                    var message = "The node is at the wrong level of nesting. This usually means a child is missing.";
+                    throw new SyntaxTreeNodeBaselineException(node, ancestors.ToArray(), expected, actual, message);
+                }
+
+                charsVerified = j;
+            }
+
+            private void AssertNameEqual(SyntaxTreeNode node, IEnumerable<SyntaxTreeNode> ancestors, string expected, string actual, ref int charsVerified)
+            {
+                var expectedName = GetName(expected, charsVerified);
+                var actualName = GetName(actual, charsVerified);
+
+                if (!string.Equals(expectedName, actualName))
+                {
+                    var message = $"Node names are not equal.";
+                    throw new SyntaxTreeNodeBaselineException(node, ancestors.ToArray(), expected, actual, message);
+                }
+
+                charsVerified += expectedName.Length;
+            }
+
+            // Either both strings need to have a delimiter next or neither should.
+            private void AssertDelimiter(SyntaxTreeNode node, string expected, string actual, bool required, ref int charsVerified)
+            {
+                if (charsVerified == expected.Length && required)
+                {
+                    throw new InvalidOperationException($"Baseline text is not well-formed: '{expected}'.");
+                }
+
+                if (charsVerified == actual.Length && required)
+                {
+                    throw new InvalidOperationException($"Baseline text is not well-formed: '{actual}'.");
+                }
+
+                if (charsVerified == expected.Length && charsVerified == actual.Length)
+                {
+                    return;
+                }
+
+                var expectedDelimiter = expected.IndexOf(" - ", charsVerified);
+                if (expectedDelimiter != charsVerified && expectedDelimiter != -1)
+                {
+                    throw new InvalidOperationException($"Baseline text is not well-formed: '{actual}'.");
+                }
+
+                var actualDelimiter = actual.IndexOf(" - ", charsVerified);
+                if (actualDelimiter != charsVerified && actualDelimiter != -1)
+                {
+                    throw new InvalidOperationException($"Baseline text is not well-formed: '{actual}'.");
+                }
+
+                Assert.Equal(expectedDelimiter, actualDelimiter);
+
+                charsVerified += 3;
+            }
+
+            private void AssertLocationEqual(SyntaxTreeNode node, IEnumerable<SyntaxTreeNode> ancestors, string expected, string actual, ref int charsVerified)
+            {
+                var expectedLocation = GetLocation(expected, charsVerified);
+                var actualLocation = GetLocation(actual, charsVerified);
+
+                if (!string.Equals(expectedLocation, actualLocation))
+                {
+                    var message = $"Locations are not equal.";
+                    throw new SyntaxTreeNodeBaselineException(node, ancestors.ToArray(), expected, actual, message);
+                }
+
+                charsVerified += expectedLocation.Length;
+            }
+
+            private void AssertContentEqual(SyntaxTreeNode node, IEnumerable<SyntaxTreeNode> ancestors, string expected, string actual, ref int charsVerified)
+            {
+                var expectedContent = GetContent(expected, charsVerified);
+                var actualContent = GetContent(actual, charsVerified);
+
+                if (!string.Equals(expectedContent, actualContent))
+                {
+                    var message = $"Contents are not equal.";
+                    throw new SyntaxTreeNodeBaselineException(node, ancestors.ToArray(), expected, actual, message);
+                }
+
+                charsVerified += expectedContent.Length;
+            }
+
+            private string GetName(string text, int start)
+            {
+                var delimiter = text.IndexOf(" - ", start);
+                if (delimiter == -1)
+                {
+                    throw new InvalidOperationException($"Baseline text is not well-formed: '{text}'.");
+                }
+
+                return text.Substring(start, delimiter - start);
+            }
+
+            private string GetLocation(string text, int start)
+            {
+                var delimiter = text.IndexOf(" - ", start);
+                return delimiter == -1 ? text.Substring(start) : text.Substring(start, delimiter - start);
+            }
+
+            private string GetContent(string text, int start)
+            {
+                return start == text.Length ? string.Empty : text.Substring(start);
+            }
+
+            private class SyntaxTreeNodeBaselineException : XunitException
+            {
+                public SyntaxTreeNodeBaselineException(SyntaxTreeNode node, SyntaxTreeNode[] ancestors, string expected, string actual, string userMessage)
+                    : base(Format(node, ancestors, expected, actual, userMessage))
+                {
+                    Node = node;
+                    Expected = expected;
+                    Actual = actual;
+                }
+
+                public SyntaxTreeNode Node { get; }
+
+                public string Actual { get; }
+
+                public string Expected { get; }
+
+                private static string Format(SyntaxTreeNode node, SyntaxTreeNode[] ancestors, string expected, string actual, string userMessage)
+                {
+                    var builder = new StringBuilder();
+                    builder.AppendLine(userMessage);
+                    builder.AppendLine();
+
+                    if (expected != null)
+                    {
+                        builder.Append("Expected: ");
+                        builder.AppendLine(expected);
+                    }
+
+                    if (actual != null)
+                    {
+                        builder.Append("Actual: ");
+                        builder.AppendLine(actual);
+                    }
+
+                    if (ancestors != null)
+                    {
+                        builder.AppendLine();
+                        builder.AppendLine("Path:");
+
+                        foreach (var ancestor in ancestors)
+                        {
+                            builder.AppendLine(ancestor.ToString());
+                        }
+                    }
+
+                    return builder.ToString();
+                }
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Razor.Test.Common/Language/Legacy/SyntaxTreeNodeWalker.cs

@@ -0,0 +1,40 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace Microsoft.AspNetCore.Razor.Language.Legacy
+{
+    internal class SyntaxTreeNodeWalker : ParserVisitor
+    {
+        private readonly List<SyntaxTreeNode> _ancestors = new List<SyntaxTreeNode>();
+
+        protected IReadOnlyList<SyntaxTreeNode> Ancestors => _ancestors;
+
+        protected SyntaxTreeNode Parent => _ancestors.Count > 0 ? _ancestors[0] : null;
+
+        public override void VisitDefault(Block block)
+        {
+            var children = block.Children;
+            if (block.Children.Count == 0)
+            {
+                return;
+            }
+
+            _ancestors.Insert(0, block);
+
+            try
+            {
+                for (var i = 0; i < block.Children.Count; i++)
+                {
+                    var child = children[i];
+                    Visit(child);
+                }
+            }
+            finally
+            {
+                _ancestors.RemoveAt(0);
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Razor.Test.Common/Language/Legacy/SyntaxTreeNodeWriter.cs

@@ -0,0 +1,244 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.IO;
+
+namespace Microsoft.AspNetCore.Razor.Language.Legacy
+{
+    internal class SyntaxTreeNodeWriter : ParserVisitor
+    {
+        private readonly TextWriter _writer;
+
+        public int Depth { get; set; }
+
+        public SyntaxTreeNodeWriter(TextWriter writer)
+        {
+            _writer = writer;
+        }
+
+        public override void VisitDefault(Block block)
+        {
+            WriteBlock(block);
+        }
+
+        public override void VisitDefault(Span span)
+        {
+            WriteSpan(span);
+        }
+
+        public override void VisitTagHelperBlock(TagHelperChunkGenerator chunkGenerator, Block block)
+        {
+            WriteBlock(block);
+            
+            if (block is TagHelperBlock tagHelperBlock)
+            {
+                WriteSeparator();
+                Write(tagHelperBlock.TagName);
+                WriteSeparator();
+                Write(tagHelperBlock.TagMode);
+
+                foreach (var descriptor in tagHelperBlock.Binding.Descriptors)
+                {
+                    WriteSeparator();
+
+                    // Get the type name without the namespace.
+                    var typeName = descriptor.Name.Substring(descriptor.Name.LastIndexOf('.') + 1);
+                    Write(typeName);
+                }
+            }
+        }
+
+        public override void VisitAttributeBlock(AttributeBlockChunkGenerator chunkGenerator, Block block)
+        {
+            WriteBlock(block);
+            WriteSeparator();
+            Write(chunkGenerator.Name);
+            WriteSeparator();
+            WriteLocationTaggedString(chunkGenerator.Prefix);
+            WriteSeparator();
+            WriteLocationTaggedString(chunkGenerator.Suffix);
+        }
+
+        public override void VisitCommentBlock(RazorCommentChunkGenerator chunkGenerator, Block block)
+        {
+            WriteBlock(block);
+        }
+
+        public override void VisitDirectiveBlock(DirectiveChunkGenerator chunkGenerator, Block block)
+        {
+            WriteBlock(block);
+            WriteSeparator();
+            Write(chunkGenerator.Descriptor.Directive);
+            WriteSeparator();
+            Write(chunkGenerator.Descriptor.Kind);
+            WriteSeparator();
+            Write(chunkGenerator.Descriptor.Usage);
+        }
+
+        public override void VisitDynamicAttributeBlock(DynamicAttributeBlockChunkGenerator chunkGenerator, Block block)
+        {
+            WriteBlock(block);
+            WriteSeparator();
+            WriteLocationTaggedString(chunkGenerator.Prefix);
+            WriteSeparator();
+            WriteSourceLocation(chunkGenerator.ValueStart);
+        }
+
+        public override void VisitExpressionBlock(ExpressionChunkGenerator chunkGenerator, Block block)
+        {
+            WriteBlock(block);
+        }
+
+        public override void VisitTemplateBlock(TemplateBlockChunkGenerator chunkGenerator, Block block)
+        {
+            WriteBlock(block);
+        }
+
+        public override void VisitMarkupSpan(MarkupChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+        }
+
+        public override void VisitAddTagHelperSpan(AddTagHelperChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+            WriteSeparator();
+            Write(chunkGenerator.LookupText);
+            WriteSeparator();
+            Write(chunkGenerator.DirectiveText);
+            WriteSeparator();
+            Write(chunkGenerator.TypePattern);
+            WriteSeparator();
+            Write(chunkGenerator.AssemblyName);
+        }
+
+        public override void VisitExpressionSpan(ExpressionChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+        }
+
+        public override void VisitImportSpan(AddImportChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+            WriteSeparator();
+            Write(chunkGenerator.Namespace);
+        }
+
+        public override void VisitLiteralAttributeSpan(LiteralAttributeChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+            WriteSeparator();
+            WriteLocationTaggedString(chunkGenerator.Prefix);
+            WriteSeparator();
+            WriteLocationTaggedString(chunkGenerator.Value);
+        }
+
+        public override void VisitRemoveTagHelperSpan(RemoveTagHelperChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+            WriteSeparator();
+            Write(chunkGenerator.LookupText);
+            WriteSeparator();
+            Write(chunkGenerator.DirectiveText);
+            WriteSeparator();
+            Write(chunkGenerator.TypePattern);
+            WriteSeparator();
+            Write(chunkGenerator.AssemblyName);
+        }
+
+        public override void VisitTagHelperPrefixDirectiveSpan(TagHelperPrefixDirectiveChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+            WriteSeparator();
+            Write(chunkGenerator.Prefix);
+            WriteSeparator();
+            Write(chunkGenerator.DirectiveText);
+        }
+
+        public override void VisitStatementSpan(StatementChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+        }
+
+        public override void VisitDirectiveToken(DirectiveTokenChunkGenerator chunkGenerator, Span span)
+        {
+            WriteSpan(span);
+            WriteSeparator();
+            Write(chunkGenerator.Descriptor.Kind);
+            WriteSeparator();
+            Write(chunkGenerator.Descriptor.Name);
+            WriteSeparator();
+            Write($"Optional: {chunkGenerator.Descriptor.Optional}");
+        }
+
+        protected void WriteBlock(Block block)
+        {
+            WriteIndent();
+            Write($"{block.Type} block");
+            WriteSeparator();
+            Write(block.ChunkGenerator.GetType().Name);
+            WriteSeparator();
+            Write(block.Length);
+            WriteSeparator();
+            WriteSourceLocation(block.Start);
+        }
+
+        protected void WriteSpan(Span span)
+        {
+            WriteIndent();
+            Write($"{span.Kind} span");
+            WriteSeparator();
+            Write(span.ChunkGenerator.GetType().Name);
+            WriteSeparator();
+            Write(span.EditHandler);
+            WriteSeparator();
+            Write(span.Content);
+            WriteSeparator();
+            WriteSourceLocation(span.Start);
+        }
+
+        protected void WriteSourceLocation(SourceLocation location)
+        {
+            Write(location);
+        }
+
+        protected void WriteLocationTaggedString(LocationTagged<string> item)
+        {
+            Write(item.ToString("F", null));
+        }
+
+        protected void WriteIndent()
+        {
+            for (var i = 0; i < Depth; i++)
+            {
+                for (var j = 0; j < 4; j++)
+                {
+                    Write(' ');
+                }
+            }
+        }
+
+        protected void WriteSeparator()
+        {
+            Write(" - ");
+        }
+
+        protected void WriteNewLine()
+        {
+            _writer.WriteLine();
+        }
+
+        protected void Write(object value)
+        {
+            if (value is string stringValue)
+            {
+                stringValue = stringValue.Replace("\r\n", "LF");
+                _writer.Write(stringValue);
+                return;
+            }
+
+            _writer.Write(value);
+        }
+    }
+}