Don't show HTML snippets in style, script, or html comment blocks (#12021)

* Don't show HTML snippets in style, script, or html comment blocks

* CR feedback - optimize tree walk looking for script, style and html comments

Author: alexgav

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Completion/Delegation/DelegatedCompletionHelper.cs

@@ -230,6 +230,12 @@ public static bool ShouldIncludeSnippets(RazorCodeDocument razorCodeDocument, in
 
         if (startOrEndTag is null)
         {
+            if (IsInScriptOrStyleOrHtmlComment(node))
+            {
+                // If we're in a style, script, or HTML comment block, we don't want to include HTML snippets.
+                return false;
+            }
+
             return token.Kind is not (SyntaxKind.OpenAngle or SyntaxKind.CloseAngle);
         }
 
@@ -241,6 +247,29 @@ public static bool ShouldIncludeSnippets(RazorCodeDocument razorCodeDocument, in
         }
 
         return !startOrEndTag.Span.Contains(absoluteIndex);
+
+        static bool IsInScriptOrStyleOrHtmlComment(AspNetCore.Razor.Language.Syntax.SyntaxNode? initialNode)
+        {
+            for (var node = initialNode; node != null; node = node.Parent)
+            {
+                if (node is MarkupElementSyntax elementNode)
+                {
+                    if (RazorSyntaxFacts.IsStyleBlock(elementNode) || RazorSyntaxFacts.IsScriptBlock(elementNode))
+                    {
+                        return true;
+                    }
+
+                    // If we're in an element but it's not a script or style block, stop looking
+                    break;
+                }
+                else if (node is MarkupCommentBlockSyntax commentNode)
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
     }
 
     public static object? GetOriginalCompletionItemData(

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

@@ -207,4 +207,19 @@ internal static bool IsInUsingDirective(RazorSyntaxNode node)
 
         return false;
     }
+
+    internal static bool IsElementWithName(MarkupElementSyntax? element, string name)
+    {
+        return string.Equals(element?.StartTag.Name.Content, name, StringComparison.OrdinalIgnoreCase);
+    }
+
+    internal static bool IsStyleBlock(MarkupElementSyntax? node)
+    {
+        return IsElementWithName(node, "style");
+    }
+
+    internal static bool IsScriptBlock(MarkupElementSyntax? node)
+    {
+        return IsElementWithName(node, "script");
+    }
 }

src/Razor/test/Microsoft.VisualStudio.Razor.IntegrationTests/CompletionIntegrationTests.cs

@@ -438,14 +438,28 @@ await TestServices.SolutionExplorer.AddFileAsync(
     [InlineData("</PageTitle")]
     [InlineData("<div")]
     [InlineData("</div")]
+    [InlineData("// script block ")]
+    [InlineData("/* style block ")]
+    [InlineData("<!-- comment block ")]
     [WorkItem("https://github.com/dotnet/razor/issues/9427")]
-    public async Task Snippets_DoNotTrigger_InsideTag(string tag)
+    // Do not trigger snippets in start tags, end tags, script blocks, style blocks, or comments
+    public async Task Snippets_DoNotTrigger_InDisallowedContext(string tag)
     {
         await TestServices.SolutionExplorer.AddFileAsync(
             RazorProjectConstants.BlazorProjectName,
             "Test.razor",
             """
-            @page "Test"
+            @page "/Test"
+
+            <script>
+                // script block 
+            </script>
+
+            <style>
+                /* style block  */
+            </style>
+
+            <!-- comment block  -->
 
             <PageTitle>Test</PageTitle>