Addressed feedback

Author: ajaybhargavb

src/Microsoft.AspNetCore.Razor.Language/Syntax/MarkupElementRewriter.cs

@@ -5,13 +5,12 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using System.Text;
 
 namespace Microsoft.AspNetCore.Razor.Language.Syntax
 {
     internal static class MarkupElementRewriter
     {
-        public static RazorSyntaxTree AddMarkupElement(RazorSyntaxTree syntaxTree)
+        public static RazorSyntaxTree AddMarkupElements(RazorSyntaxTree syntaxTree)
         {
             var rewriter = new AddMarkupElementRewriter();
             var rewrittenRoot = rewriter.Visit(syntaxTree.Root);
@@ -20,7 +19,7 @@ public static RazorSyntaxTree AddMarkupElement(RazorSyntaxTree syntaxTree)
             return newSyntaxTree;
         }
 
-        public static RazorSyntaxTree RemoveMarkupElement(RazorSyntaxTree syntaxTree)
+        public static RazorSyntaxTree RemoveMarkupElements(RazorSyntaxTree syntaxTree)
         {
             var rewriter = new RemoveMarkupElementRewriter();
             var rewrittenRoot = rewriter.Visit(syntaxTree.Root);
@@ -173,14 +172,17 @@ private void BuildMarkupElement(List<SyntaxNode> rewrittenChildren, MarkupTagBlo
                 // The call to SyntaxNode.ReplaceNodes() later will take care removing the nodes whose replacement is null.
 
                 var body = tagChildren.Where(t => t != null).ToList();
-                var rewritten = SyntaxFactory.MarkupElement(startTag, new SyntaxList<RazorSyntaxNode>(body), endTag: endTag);
+                var rewritten = SyntaxFactory.MarkupElement(startTag, new SyntaxList<RazorSyntaxNode>(body), endTag);
                 if (startTag != null)
                 {
                     // If there was a start tag, that is where we want to put our new element.
                     TrackChild(rewritten, rewrittenChildren);
                 }
 
-                tagChildren.ForEach(c => TrackChild(null, rewrittenChildren));
+                foreach (var child in tagChildren)
+                {
+                    TrackChild(null, rewrittenChildren);
+                }
                 if (endTag != null)
                 {
                     TrackChild(startTag == null ? rewritten : null, rewrittenChildren);

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

@@ -122,13 +122,25 @@ public void Rewrites_MalformedVoidTags_RecoversSuccessfully()
             RewriterTest(content);
         }
 
+        [Fact]
+        public void Rewrites_IncompleteTags()
+        {
+            // Arrange
+            var content = @"
+<<div>>Foo</</div><   >
+";
+
+            // Act & Assert
+            RewriterTest(content);
+        }
+
         private void RewriterTest(string input)
         {
             var syntaxTree = ParseDocument(input, designTime: false);
-            var rewritten = MarkupElementRewriter.AddMarkupElement(syntaxTree);
+            var rewritten = MarkupElementRewriter.AddMarkupElements(syntaxTree);
             BaselineTest(rewritten);
 
-            var unrewritten = MarkupElementRewriter.RemoveMarkupElement(rewritten);
+            var unrewritten = MarkupElementRewriter.RemoveMarkupElements(rewritten);
             Assert.Equal(syntaxTree.Root.SerializedValue, unrewritten.Root.SerializedValue);
         }
     }

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/MarkupElementRewriterTest/Rewrites_IncompleteTags.cspans.txt

@@ -0,0 +1,8 @@
+Markup span at (0:0,0 [2] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [27] )
+Markup span at (2:1,0 [1] ) (Accepts:Any) - Parent: Tag block at (2:1,0 [1] )
+Markup span at (3:1,1 [5] ) (Accepts:Any) - Parent: Tag block at (3:1,1 [5] )
+Markup span at (8:1,6 [4] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [27] )
+Markup span at (12:1,10 [2] ) (Accepts:Any) - Parent: Tag block at (12:1,10 [2] )
+Markup span at (14:1,12 [6] ) (Accepts:Any) - Parent: Tag block at (14:1,12 [6] )
+Markup span at (20:1,18 [5] ) (Accepts:Any) - Parent: Tag block at (20:1,18 [5] )
+Markup span at (25:1,23 [2] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [27] )

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/ParserTests/MarkupElementRewriterTest/Rewrites_IncompleteTags.stree.txt

@@ -0,0 +1,36 @@
+RazorDocument - [0..27)::27 - [LF<<div>>Foo</</div><   >LF]
+    MarkupBlock - [0..27)::27
+        MarkupTextLiteral - [0..2)::2 - [LF] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            NewLine;[LF];
+        MarkupElement - [2..3)::1
+            MarkupTagBlock - [2..3)::1 - [<]
+                MarkupTextLiteral - [2..3)::1 - [<] - Gen<Markup> - SpanEditHandler;Accepts:Any
+                    OpenAngle;[<];
+        MarkupElement - [3..20)::17
+            MarkupTagBlock - [3..8)::5 - [<div>]
+                MarkupTextLiteral - [3..8)::5 - [<div>] - Gen<Markup> - SpanEditHandler;Accepts:Any
+                    OpenAngle;[<];
+                    Text;[div];
+                    CloseAngle;[>];
+            MarkupTextLiteral - [8..12)::4 - [>Foo] - Gen<Markup> - SpanEditHandler;Accepts:Any
+                CloseAngle;[>];
+                Text;[Foo];
+            MarkupElement - [12..14)::2
+                MarkupTagBlock - [12..14)::2 - [</]
+                    MarkupTextLiteral - [12..14)::2 - [</] - Gen<Markup> - SpanEditHandler;Accepts:Any
+                        OpenAngle;[<];
+                        ForwardSlash;[/];
+            MarkupTagBlock - [14..20)::6 - [</div>]
+                MarkupTextLiteral - [14..20)::6 - [</div>] - Gen<Markup> - SpanEditHandler;Accepts:Any
+                    OpenAngle;[<];
+                    ForwardSlash;[/];
+                    Text;[div];
+                    CloseAngle;[>];
+        MarkupElement - [20..25)::5
+            MarkupTagBlock - [20..25)::5 - [<   >]
+                MarkupTextLiteral - [20..25)::5 - [<   >] - Gen<Markup> - SpanEditHandler;Accepts:Any
+                    OpenAngle;[<];
+                    Whitespace;[   ];
+                    CloseAngle;[>];
+        MarkupTextLiteral - [25..27)::2 - [LF] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            NewLine;[LF];