diff --git a/src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Completion/Delegation/DelegatedCompletionListProvider.cs b/src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Completion/Delegation/DelegatedCompletionListProvider.cs
index 35ffb1fba6a..900b1fcc39b 100644
--- a/src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Completion/Delegation/DelegatedCompletionListProvider.cs
+++ b/src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Completion/Delegation/DelegatedCompletionListProvider.cs
@@ -39,7 +39,7 @@ public DelegatedCompletionListProvider(
         IClientConnection clientConnection,
         CompletionListCache completionListCache)
     {
-        _responseRewriters = responseRewriters.OrderBy(rewriter => rewriter.Order).ToImmutableArray();
+        _responseRewriters = responseRewriters.OrderByAsArray(static x => x.Order);
         _documentMappingService = documentMappingService;
         _clientConnection = clientConnection;
         _completionListCache = completionListCache;
@@ -57,7 +57,9 @@ public DelegatedCompletionListProvider(
         Guid correlationId,
         CancellationToken cancellationToken)
     {
-        var positionInfo = await _documentMappingService.GetPositionInfoAsync(documentContext, absoluteIndex, cancellationToken).ConfigureAwait(false);
+        var positionInfo = await _documentMappingService
+            .GetPositionInfoAsync(documentContext, absoluteIndex, cancellationToken)
+            .ConfigureAwait(false);
 
         if (positionInfo.LanguageKind == RazorLanguageKind.Razor)
         {
diff --git a/src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Completion/Delegation/DelegatedCompletionListProviderTest.cs b/src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Completion/Delegation/DelegatedCompletionListProviderTest.cs
index faf9392f1f1..20845191b36 100644
--- a/src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Completion/Delegation/DelegatedCompletionListProviderTest.cs
+++ b/src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Completion/Delegation/DelegatedCompletionListProviderTest.cs
@@ -9,12 +9,15 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.LanguageServer.Hosting;
+using Microsoft.AspNetCore.Razor.Test.Common;
 using Microsoft.AspNetCore.Razor.Test.Common.LanguageServer;
+using Microsoft.CodeAnalysis.Razor.DocumentMapping;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Razor.Protocol;
 using Microsoft.CodeAnalysis.Testing;
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.LanguageServer.Protocol;
+using Moq;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -284,15 +287,16 @@ public async Task ShouldIncludeSnippets(string input, bool shouldIncludeSnippets
         var codeDocument = CreateCodeDocument(code);
         var documentContext = TestDocumentContext.From("C:/path/to/file.cshtml", codeDocument, hostDocumentVersion: 1337);
 
-        var documentMappingService = new TestDocumentMappingService()
-        {
-            LanguageKind = RazorLanguageKind.Html,
-            GeneratedPosition = new LinePosition(0, cursorPosition)
-        };
+        var generatedPosition = new LinePosition(0, cursorPosition);
+
+        var documentMappingServiceMock = new StrictMock<IDocumentMappingService>();
+        documentMappingServiceMock
+            .Setup(x => x.TryMapToGeneratedDocumentPosition(It.IsAny<IRazorGeneratedDocument>(), It.IsAny<int>(), out generatedPosition, out It.Ref<int>.IsAny))
+            .Returns(true);
 
         var completionProvider = new DelegatedCompletionListProvider(
-            Array.Empty<DelegatedCompletionResponseRewriter>(),
-            documentMappingService,
+            responseRewriters: [],
+            documentMappingServiceMock.Object,
             clientConnection,
             new CompletionListCache());
 
diff --git a/src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Completion/TestDocumentMappingService.cs b/src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Completion/TestDocumentMappingService.cs
deleted file mode 100644
index 2dd5836ce16..00000000000
--- a/src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Completion/TestDocumentMappingService.cs
+++ /dev/null
@@ -1,66 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-using System;
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using System.Threading;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore.Razor.Language;
-using Microsoft.CodeAnalysis.Razor.DocumentMapping;
-using Microsoft.CodeAnalysis.Razor.Protocol;
-using Microsoft.CodeAnalysis.Text;
-
-namespace Microsoft.AspNetCore.Razor.LanguageServer.Completion;
-
-internal class TestDocumentMappingService : IDocumentMappingService
-{
-    public RazorLanguageKind LanguageKind { get; set; }
-    public LinePosition? GeneratedPosition { get; set; }
-    public int GeneratedIndex { get; set; }
-
-    public IEnumerable<TextChange> GetHostDocumentEdits(IRazorGeneratedDocument generatedDocument, ImmutableArray<TextChange> generatedDocumentEdits)
-        => [];
-
-    public RazorLanguageKind GetLanguageKind(RazorCodeDocument codeDocument, int hostDocumentIndex, bool rightAssociative)
-        => LanguageKind;
-
-    public Task<(Uri MappedDocumentUri, LinePositionSpan MappedRange)> MapToHostDocumentUriAndRangeAsync(Uri generatedDocumentUri, LinePositionSpan generatedDocumentRange, CancellationToken cancellationToken)
-    {
-        throw new NotImplementedException();
-    }
-
-    public bool TryMapToGeneratedDocumentOrNextCSharpPosition(IRazorGeneratedDocument generatedDocument, int hostDocumentIndex, out LinePosition generatedPosition, out int generatedIndex)
-    {
-        throw new NotImplementedException();
-    }
-
-    public bool TryMapToGeneratedDocumentPosition(IRazorGeneratedDocument generatedDocument, int hostDocumentIndex, out LinePosition generatedPosition, out int generatedIndex)
-    {
-        if (GeneratedPosition is null)
-        {
-            generatedPosition = default;
-            generatedIndex = default;
-            return false;
-        }
-
-        generatedPosition = GeneratedPosition.Value;
-        generatedIndex = GeneratedIndex;
-        return true;
-    }
-
-    public bool TryMapToGeneratedDocumentRange(IRazorGeneratedDocument generatedDocument, LinePositionSpan hostDocumentRange, out LinePositionSpan generatedDocumentRange)
-    {
-        throw new NotImplementedException();
-    }
-
-    public bool TryMapToHostDocumentPosition(IRazorGeneratedDocument generatedDocument, int generatedDocumentIndex, out LinePosition hostDocumentPosition, out int hostDocumentIndex)
-    {
-        throw new NotImplementedException();
-    }
-
-    public bool TryMapToHostDocumentRange(IRazorGeneratedDocument generatedDocument, LinePositionSpan generatedDocumentRange, MappingBehavior mappingBehavior, out LinePositionSpan hostDocumentRange)
-    {
-        throw new NotImplementedException();
-    }
-}