Add comprehensive tests for CohostWrapWithTagEndpoint

Co-authored-by: davidwengier <754264+davidwengier@users.noreply.github.com>

Author: Copilot

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/Cohost/CohostWrapWithTagEndpointTest.cs

@@ -0,0 +1,118 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Razor.Protocol;
+using Microsoft.CodeAnalysis.Testing;
+using Microsoft.VisualStudio.Razor.LanguageClient.WrapWithTag;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Microsoft.VisualStudio.Razor.LanguageClient.Cohost;
+
+public class CohostWrapWithTagEndpointTest(ITestOutputHelper testOutputHelper) : CohostEndpointTestBase(testOutputHelper)
+{
+    [Fact]
+    public async Task ValidHtmlLocation_ReturnsResult()
+    {
+        await VerifyWrapWithTagAsync(
+            input: """
+                <div>
+                    [||]
+                </div>
+                """,
+            htmlResponse: new VSInternalWrapWithTagResponse(
+                LspFactory.CreateSingleLineRange(start: (0, 0), length: 10),
+                [LspFactory.CreateTextEdit(position: (0, 0), "<p></p>")]
+            ),
+            expected: new VSInternalWrapWithTagResponse(
+                LspFactory.CreateSingleLineRange(start: (0, 0), length: 10),
+                [LspFactory.CreateTextEdit(position: (0, 0), "<p></p>")]
+            ));
+    }
+
+    [Fact]
+    public async Task CSharpLocation_ReturnsNull()
+    {
+        await VerifyWrapWithTagAsync(
+            input: """
+                @code {
+                    [||]
+                }
+                """,
+            htmlResponse: null,
+            expected: null);
+    }
+
+    [Fact]
+    public async Task ImplicitExpression_ReturnsResult()
+    {
+        await VerifyWrapWithTagAsync(
+            input: """
+                <div>
+                    @[||]currentCount
+                </div>
+                """,
+            htmlResponse: new VSInternalWrapWithTagResponse(
+                LspFactory.CreateSingleLineRange(start: (1, 4), length: 16),
+                [LspFactory.CreateTextEdit(position: (1, 4), "<span>@currentCount</span>")]
+            ),
+            expected: new VSInternalWrapWithTagResponse(
+                LspFactory.CreateSingleLineRange(start: (1, 4), length: 16),
+                [LspFactory.CreateTextEdit(position: (1, 4), "<span>@currentCount</span>")]
+            ));
+    }
+
+    [Fact]
+    public async Task HtmlWithTildes_FixesTextEdits()
+    {
+        await VerifyWrapWithTagAsync(
+            input: """
+                <div>
+                    [||]
+                </div>
+                """,
+            htmlResponse: new VSInternalWrapWithTagResponse(
+                LspFactory.CreateSingleLineRange(start: (0, 0), length: 10),
+                [LspFactory.CreateTextEdit(position: (0, 0), "~~~<p>~~~~</p>~~~")]
+            ),
+            expected: new VSInternalWrapWithTagResponse(
+                LspFactory.CreateSingleLineRange(start: (0, 0), length: 10),
+                [LspFactory.CreateTextEdit(position: (0, 0), "<p></p>")]
+            ));
+    }
+
+    private async Task VerifyWrapWithTagAsync(string input, VSInternalWrapWithTagResponse? htmlResponse, VSInternalWrapWithTagResponse? expected)
+    {
+        TestFileMarkupParser.GetSpan(input, out input, out var span);
+        var document = CreateProjectAndRazorDocument(input);
+        var sourceText = await document.GetTextAsync(DisposalToken);
+
+        var requestInvoker = new TestHtmlRequestInvoker([(LanguageServerConstants.RazorWrapWithTagEndpoint, htmlResponse)]);
+
+        var endpoint = new CohostWrapWithTagEndpoint(RemoteServiceInvoker, FilePathService, requestInvoker);
+
+        var request = new VSInternalWrapWithTagParams(
+            sourceText.GetRange(span),
+            "div",
+            new FormattingOptions(),
+            new VersionedTextDocumentIdentifier()
+            {
+                DocumentUri = new(document.CreateUri())
+            });
+
+        var result = await endpoint.GetTestAccessor().HandleRequestAsync(request, document, DisposalToken);
+
+        if (expected is null)
+        {
+            Assert.Null(result);
+        }
+        else
+        {
+            Assert.NotNull(result);
+            Assert.Equal(expected.TagRange, result.TagRange);
+            Assert.Equal(expected.TextEdits, result.TextEdits);
+        }
+    }
+}