Prereq for converting tag helper tests

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

@@ -68,6 +68,12 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                 .OrderBy(error => error.Span.AbsoluteIndex)
                 .ToList();
 
+            if (UseBaselineTests && !IsTheory)
+            {
+                BaselineTest(actualTree, verifySyntaxTree: false, actualErrors.ToArray());
+                return;
+            }
+
             EvaluateRazorErrors(actualErrors, expectedErrors.ToList());
             EvaluateParseTree(actualTree, expectedOutput);
         }

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

@@ -162,16 +162,24 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             return Regex.Replace(content, "(?<!\r)\n", "\r\n", RegexOptions.None, TimeSpan.FromSeconds(10));
         }
 
-        internal virtual void BaselineTest(RazorSyntaxTree syntaxTree)
+        internal virtual void BaselineTest(RazorSyntaxTree syntaxTree, bool verifySyntaxTree = true)
         {
-            SyntaxTreeVerifier.Verify(syntaxTree);
+            if (verifySyntaxTree)
+            {
+                SyntaxTreeVerifier.Verify(syntaxTree);
+            }
+
             AssertSyntaxTreeNodeMatchesBaseline(syntaxTree);
         }
 
-        internal virtual void BaselineTest(Block root)
+        internal virtual void BaselineTest(Block root, bool verifySyntaxTree = true, params RazorDiagnostic[] diagnostics)
         {
-            SyntaxTreeVerifier.Verify(root);
+            if (verifySyntaxTree)
-            AssertSyntaxTreeNodeMatchesBaseline(root);
+            {
+                SyntaxTreeVerifier.Verify(root);
+            }
+
+            AssertSyntaxTreeNodeMatchesBaseline(root, diagnostics);
         }
 
         internal RazorSyntaxTree ParseBlock(string document, bool designTime)

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

@@ -35,11 +35,11 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             
             if (block is TagHelperBlock tagHelperBlock)
             {
+                // Write tag name
                 WriteSeparator();
                 Write(tagHelperBlock.TagName);
-                WriteSeparator();
-                Write(tagHelperBlock.TagMode);
 
+                // Write descriptors
                 foreach (var descriptor in tagHelperBlock.Binding.Descriptors)
                 {
                     WriteSeparator();
@@ -48,6 +48,36 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                     var typeName = descriptor.Name.Substring(descriptor.Name.LastIndexOf('.') + 1);
                     Write(typeName);
                 }
+
+                // Write tag mode, start tag and end tag
+                Depth++;
+                WriteNewLine();
+                WriteIndent();
+                Write(tagHelperBlock.TagMode);
+                WriteSeparator();
+                Write(GetNodeContent(tagHelperBlock.SourceStartTag));
+                if (tagHelperBlock.SourceEndTag != null)
+                {
+                    Write(" ... ");
+                    Write(GetNodeContent(tagHelperBlock.SourceEndTag));
+                }
+
+                // Write attributes
+                foreach (var attribute in tagHelperBlock.Attributes)
+                {
+                    WriteNewLine();
+                    WriteIndent();
+                    Write(attribute.Name);
+                    WriteSeparator();
+                    Write(attribute.AttributeStructure);
+
+                    Depth++;
+                    WriteNewLine();
+                    // Recursively render attribute value
+                    VisitNode(attribute.Value);
+                    Depth--;
+                }
+                Depth--;
             }
         }
 
@@ -226,5 +256,41 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
 
             _writer.Write(value);
         }
+
+        private string GetNodeContent(SyntaxTreeNode node)
+        {
+            if (node is Span span)
+            {
+                return span.Content;
+            }
+            else if (node is Block block)
+            {
+                var content = string.Empty;
+                foreach (var child in block.Children)
+                {
+                    content += GetNodeContent(child);
+                }
+
+                return content;
+            }
+
+            return string.Empty;
+        }
+
+        private void VisitNode(SyntaxTreeNode node)
+        {
+            Visit(node);
+
+            if (node is Block block)
+            {
+                Depth++;
+                foreach (var child in block.Children)
+                {
+                    WriteNewLine();
+                    VisitNode(child);
+                }
+                Depth--;
+            }
+        }
     }
 }