Add a code action to promote a using directive

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Mvc/MvcImportProjectFeature.cs

@@ -14,7 +14,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions;
 
 internal class MvcImportProjectFeature : RazorProjectEngineFeatureBase, IImportProjectFeature
 {
-    private const string ImportsFileName = "_ViewImports.cshtml";
+    internal const string ImportsFileName = "_ViewImports.cshtml";
 
     public IReadOnlyList<RazorProjectItem> GetImports(RazorProjectItem projectItem)
     {

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Extensions/IServiceCollectionExtensions.cs

@@ -155,6 +155,8 @@ internal static class IServiceCollectionExtensions
         services.AddSingleton<IRazorCodeActionResolver, AddUsingsCodeActionResolver>();
         services.AddSingleton<IRazorCodeActionProvider, GenerateMethodCodeActionProvider>();
         services.AddSingleton<IRazorCodeActionResolver, GenerateMethodCodeActionResolver>();
+        services.AddSingleton<IRazorCodeActionProvider, PromoteUsingCodeActionProvider>();
+        services.AddSingleton<IRazorCodeActionResolver, PromoteUsingCodeActionResolver>();
 
         // Html Code actions
         services.AddSingleton<IHtmlCodeActionProvider, HtmlCodeActionProvider>();

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Models/PromoteToUsingCodeActionParams.cs

@@ -0,0 +1,21 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System.Text.Json.Serialization;
+
+namespace Microsoft.CodeAnalysis.Razor.CodeActions.Models;
+
+internal sealed class PromoteToUsingCodeActionParams
+{
+    [JsonPropertyName("importsFileName")]
+    public required string ImportsFileName { get; init; }
+
+    [JsonPropertyName("usingDirective")]
+    public required string UsingDirective { get; init; }
+
+    [JsonPropertyName("removeStart")]
+    public required int RemoveStart { get; init; }
+
+    [JsonPropertyName("removeEnd")]
+    public required int RemoveEnd { get; init; }
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/PromoteUsingCodeActionProvider.cs

@@ -0,0 +1,72 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.Razor.Extensions;
+using Microsoft.AspNetCore.Razor.Language;
+using Microsoft.AspNetCore.Razor.Language.Components;
+using Microsoft.AspNetCore.Razor.Language.Syntax;
+using Microsoft.AspNetCore.Razor.Threading;
+using Microsoft.CodeAnalysis.Razor.CodeActions.Models;
+using Microsoft.CodeAnalysis.Razor.CodeActions.Razor;
+using Microsoft.CodeAnalysis.Razor.Protocol;
+using Microsoft.CodeAnalysis.Text;
+
+namespace Microsoft.CodeAnalysis.Razor.CodeActions;
+
+internal class PromoteUsingCodeActionProvider : IRazorCodeActionProvider
+{
+    public Task<ImmutableArray<RazorVSInternalCodeAction>> ProvideAsync(RazorCodeActionContext context, CancellationToken cancellationToken)
+    {
+        if (context.HasSelection)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        var syntaxTree = context.CodeDocument.GetSyntaxTree();
+        if (syntaxTree?.Root is null)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        var owner = syntaxTree.Root.FindNode(TextSpan.FromBounds(context.StartAbsoluteIndex, context.EndAbsoluteIndex));
+        if (owner is null)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        if (owner.FirstAncestorOrSelf<RazorDirectiveSyntax>() is not { } directive ||
+            !directive.IsUsingDirective(out _))
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        var importFileName = FileKinds.IsLegacy(context.DocumentSnapshot.FileKind)
+                ? MvcImportProjectFeature.ImportsFileName
+                : ComponentMetadata.ImportsFileName;
+
+        var line = context.CodeDocument.Source.Text.Lines.GetLineFromPosition(context.StartAbsoluteIndex);
+        var data = new PromoteToUsingCodeActionParams
+        {
+            ImportsFileName = importFileName,
+            UsingDirective = directive.GetContent(),
+            RemoveStart = line.Start,
+            RemoveEnd = line.EndIncludingLineBreak
+        };
+
+        var resolutionParams = new RazorCodeActionResolutionParams()
+        {
+            TextDocument = context.Request.TextDocument,
+            Action = LanguageServerConstants.CodeActions.PromoteUsingDirective,
+            Language = RazorLanguageKind.Razor,
+            DelegatedDocumentUri = context.DelegatedDocumentUri,
+            Data = data
+        };
+
+        var action = RazorCodeActionFactory.CreatePromoteUsingDirective(importFileName, resolutionParams);
+
+        return Task.FromResult<ImmutableArray<RazorVSInternalCodeAction>>([action]);
+    }
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/PromoteUsingCodeActionResolver.cs

@@ -0,0 +1,93 @@
+// 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.IO;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor;
+using Microsoft.AspNetCore.Razor.Language;
+using Microsoft.AspNetCore.Razor.PooledObjects;
+using Microsoft.AspNetCore.Razor.Utilities;
+using Microsoft.CodeAnalysis.Razor.CodeActions.Models;
+using Microsoft.CodeAnalysis.Razor.Formatting;
+using Microsoft.CodeAnalysis.Razor.ProjectSystem;
+using Microsoft.CodeAnalysis.Razor.Protocol;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
+using Microsoft.CodeAnalysis.Text;
+using Microsoft.VisualStudio.LanguageServer.Protocol;
+
+namespace Microsoft.CodeAnalysis.Razor.CodeActions;
+
+internal class PromoteUsingCodeActionResolver(IFileSystem fileSystem) : IRazorCodeActionResolver
+{
+    private readonly IFileSystem _fileSystem = fileSystem;
+
+    public string Action => LanguageServerConstants.CodeActions.PromoteUsingDirective;
+
+    public async Task<WorkspaceEdit?> ResolveAsync(DocumentContext documentContext, JsonElement data, RazorFormattingOptions options, CancellationToken cancellationToken)
+    {
+        var actionParams = data.Deserialize<PromoteToUsingCodeActionParams>();
+        if (actionParams is null)
+        {
+            return null;
+        }
+
+        var codeDocument = await documentContext.GetCodeDocumentAsync(cancellationToken).ConfigureAwait(false);
+        if (codeDocument.IsUnsupported())
+        {
+            return null;
+        }
+
+        var file = FilePathNormalizer.Normalize(documentContext.Uri.GetAbsoluteOrUNCPath());
+        var folder = Path.GetDirectoryName(file).AssumeNotNull();
+        var importsFile = Path.GetFullPath(Path.Combine(folder, "..", actionParams.ImportsFileName));
+        var importFileUri = new UriBuilder
+        {
+            Scheme = Uri.UriSchemeFile,
+            Path = importsFile,
+            Host = string.Empty,
+        }.Uri;
+
+        using var edits = new PooledArrayBuilder<SumType<TextDocumentEdit, CreateFile, RenameFile, DeleteFile>>();
+
+        var textToInsert = actionParams.UsingDirective;
+        var insertLocation = new LinePosition(0, 0);
+        if (!_fileSystem.FileExists(importsFile))
+        {
+            edits.Add(new CreateFile() { Uri = importFileUri });
+        }
+        else
+        {
+            var st = SourceText.From(_fileSystem.ReadFile(importsFile));
+            var lastLine = st.Lines[st.Lines.Count - 1];
+            insertLocation = new LinePosition(lastLine.LineNumber, 0);
+            if (lastLine.GetFirstNonWhitespaceOffset() is { } nonWhiteSpaceOffset)
+            {
+                // Last line isn't blank, so add a newline, and insert at the end
+                textToInsert = Environment.NewLine + textToInsert;
+                insertLocation = new LinePosition(insertLocation.Line, lastLine.SpanIncludingLineBreak.Length);
+            }
+        }
+
+        edits.Add(new TextDocumentEdit
+        {
+            TextDocument = new OptionalVersionedTextDocumentIdentifier() { Uri = importFileUri },
+            Edits = [VsLspFactory.CreateTextEdit(insertLocation, textToInsert)]
+        });
+
+        var removeRange = codeDocument.Source.Text.GetRange(actionParams.RemoveStart, actionParams.RemoveEnd);
+
+        edits.Add(new TextDocumentEdit
+        {
+            TextDocument = new OptionalVersionedTextDocumentIdentifier() { Uri = documentContext.Uri },
+            Edits = [VsLspFactory.CreateTextEdit(removeRange, string.Empty)]
+        });
+
+        return new WorkspaceEdit
+        {
+            DocumentChanges = edits.ToArray()
+        };
+    }
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/RazorCodeActionFactory.cs

@@ -18,6 +18,16 @@ internal static class RazorCodeActionFactory
     private readonly static Guid s_createExtractToComponentTelemetryId = new("af67b0a3-f84b-4808-97a7-b53e85b22c64");
     private readonly static Guid s_generateMethodTelemetryId = new("c14fa003-c752-45fc-bb29-3a123ae5ecef");
     private readonly static Guid s_generateAsyncMethodTelemetryId = new("9058ca47-98e2-4f11-bf7c-a16a444dd939");
+    private readonly static Guid s_promoteUsingDirectiveTelemetryId = new("751f9012-e37b-444a-9211-b4ebce91d96e");
+
+    public static RazorVSInternalCodeAction CreatePromoteUsingDirective(string importsFileName, RazorCodeActionResolutionParams resolutionParams)
+        => new RazorVSInternalCodeAction
+        {
+            Title = SR.FormatPromote_using_directive_to(importsFileName),
+            Data = JsonSerializer.SerializeToElement(resolutionParams),
+            TelemetryId = s_promoteUsingDirectiveTelemetryId,
+            Name = LanguageServerConstants.CodeActions.PromoteUsingDirective,
+        };
 
     public static RazorVSInternalCodeAction CreateAddComponentUsing(string @namespace, string? newTagName, RazorCodeActionResolutionParams resolutionParams)
     {

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Protocol/LanguageServerConstants.cs

@@ -45,6 +45,8 @@ internal static class LanguageServerConstants
 
         public const string AddUsing = "AddUsing";
 
+        public const string PromoteUsingDirective = "PromoteUsingDirective";
+
         public const string CodeActionFromVSCode = "CodeActionFromVSCode";
 
         /// <summary>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/SR.resx

@@ -196,4 +196,7 @@
   <data name="Statement" xml:space="preserve">
     <value>statement</value>
   </data>
+  <data name="Promote_using_directive_to" xml:space="preserve">
+    <value>Promote using directive to {0}</value>
+  </data>
 </root>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.cs.xlf

@@ -104,6 +104,11 @@
         <target state="translated">Proběhl dotaz na řádek {0} mimo rozsah {1} {2}. Dokument nemusí být aktuální.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">příkaz</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.de.xlf

@@ -104,6 +104,11 @@
         <target state="translated">Die Zeile "{0}" außerhalb des {1} Bereichs von "{2}" wurde abgefragt. Das Dokument ist möglicherweise nicht auf dem neuesten Stand.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">Anweisung</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.es.xlf

@@ -104,6 +104,11 @@
         <target state="translated">La línea '{0}' se consultó fuera del {1} rango de '{2}'. Es posible que el documento no esté actualizado.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">instrucción</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.fr.xlf

@@ -104,6 +104,11 @@
         <target state="translated">La ligne «{0}» en dehors de la plage{1} de «{2}» a été interrogée. Le document n’est peut-être pas à jour.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">déclaration</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.it.xlf

@@ -104,6 +104,11 @@
         <target state="translated">È stata eseguita una query sulla riga '{0}' non compresa nell'intervallo {1} di '{2}'. Il documento potrebbe non essere aggiornato.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">istruzione</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.ja.xlf

@@ -104,6 +104,11 @@
         <target state="translated">'{2}' の {1} 範囲外の行 '{0}' がクエリされました。ドキュメントが最新ではない可能性があります。</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">ステートメント</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.ko.xlf

@@ -104,6 +104,11 @@
         <target state="translated">'{2}'의 {1} 범위를 벗어나는 줄 '{0}'을(를) 쿼리했습니다. 문서가 최신이 아닐 수 있습니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">문</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.pl.xlf

@@ -104,6 +104,11 @@
         <target state="translated">Wykonano zapytanie wiersza "{0}" poza zakresem {1} "{2}". Dokument może być nieaktualny.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">instrukcja</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.pt-BR.xlf

@@ -104,6 +104,11 @@
         <target state="translated">A linha '{0}' fora do intervalo {1} de '{2}' foi consultada. O documento pode não estar atualizado.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">instrução</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.ru.xlf

@@ -104,6 +104,11 @@
         <target state="translated">Запрошена строка "{0}" за пределами диапазона {1} "{2}". Возможно, документ не обновлен.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">инструкция</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.tr.xlf

@@ -104,6 +104,11 @@
         <target state="translated">{1} / '{2}' aralığının dışındaki '{0}' satırı sorgulandı. Belge güncel olmayabilir.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">deyim</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.zh-Hans.xlf

@@ -104,6 +104,11 @@
         <target state="translated">查询了 "{0}" 的 {1} 范围外的行 "{2}"。文档可能不是最新的。</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">语句</target>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Resources/xlf/SR.zh-Hant.xlf

@@ -104,6 +104,11 @@
         <target state="translated">已查詢 '{2}' 之 {1} 範圍以外的行 '{0}'。文件可能不是最新狀態。</target>
         <note />
       </trans-unit>
+      <trans-unit id="Promote_using_directive_to">
+        <source>Promote using directive to {0}</source>
+        <target state="new">Promote using directive to {0}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Statement">
         <source>statement</source>
         <target state="translated">陳述式</target>

src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/CodeActions/RemoteServices.cs

@@ -49,6 +49,9 @@ internal sealed class OOPComponentAccessibilityCodeActionProvider(IFileSystem fi
 [Export(typeof(IRazorCodeActionProvider)), Shared]
 internal sealed class OOPGenerateMethodCodeActionProvider : GenerateMethodCodeActionProvider;
 
+[Export(typeof(IRazorCodeActionProvider)), Shared]
+internal sealed class OOPPromoteUsingDirectiveCodeActionProvider : PromoteUsingCodeActionProvider;
+
 [Export(typeof(ICSharpCodeActionProvider)), Shared]
 internal sealed class OOPTypeAccessibilityCodeActionProvider : TypeAccessibilityCodeActionProvider;
 
@@ -89,6 +92,10 @@ internal sealed class OOPGenerateMethodCodeActionResolver(
     IFileSystem fileSystem)
     : GenerateMethodCodeActionResolver(roslynCodeActionHelpers, documentMappingService, razorFormattingService, fileSystem);
 
+[Export(typeof(IRazorCodeActionResolver)), Shared]
+[method: ImportingConstructor]
+internal sealed class OOPPromoteUsingDirectiveCodeActionResolver(IFileSystem fileSystem) : PromoteUsingCodeActionResolver(fileSystem);
+
 [Export(typeof(ICSharpCodeActionResolver)), Shared]
 [method: ImportingConstructor]
 internal sealed class OOPCSharpCodeActionResolver(IRazorFormattingService razorFormattingService) : CSharpCodeActionResolver(razorFormattingService);

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

@@ -7,6 +7,7 @@ using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor;
+using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.PooledObjects;
 using Microsoft.AspNetCore.Razor.Telemetry;
 using Microsoft.AspNetCore.Razor.Test.Common;
@@ -15,6 +16,7 @@ using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.ExternalAccess.Razor;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.CodeActions.Models;
+using Microsoft.CodeAnalysis.Razor.Protocol;
 using Microsoft.CodeAnalysis.Razor.Protocol.CodeActions;
 using Microsoft.CodeAnalysis.Razor.Workspaces;
 using Microsoft.CodeAnalysis.Remote.Razor;
@@ -24,8 +26,8 @@ using Microsoft.VisualStudio.Razor.Settings;
 using Roslyn.Test.Utilities;
 using Xunit;
 using Xunit.Abstractions;
-using WorkspacesSR = Microsoft.CodeAnalysis.Razor.Workspaces.Resources.SR;
 using LspDiagnostic = Microsoft.VisualStudio.LanguageServer.Protocol.Diagnostic;
+using WorkspacesSR = Microsoft.CodeAnalysis.Razor.Workspaces.Resources.SR;
 
 namespace Microsoft.VisualStudio.Razor.LanguageClient.Cohost;
 
@@ -870,6 +872,150 @@ public class CohostCodeActionsEndpointTest(ITestOutputHelper testOutputHelper) :
                     """)]);
     }
 
+    [Fact]
+    public async Task PromoteUsingDirective()
+    {
+        await VerifyCodeActionAsync(
+            input: """
+                @using [||]System
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            expected: """
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            codeActionName: LanguageServerConstants.CodeActions.PromoteUsingDirective,
+            additionalExpectedFiles: [
+                (FileUri(@"..\_Imports.razor"), """
+                    @using System
+                    """)]);
+    }
+
+    [Fact]
+    public async Task PromoteUsingDirective_Mvc()
+    {
+        await VerifyCodeActionAsync(
+            input: """
+                @using [||]System
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            expected: """
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            codeActionName: LanguageServerConstants.CodeActions.PromoteUsingDirective,
+            fileKind: FileKinds.Legacy,
+            additionalExpectedFiles: [
+                (FileUri(@"..\_ViewImports.cshtml"), """
+                    @using System
+                    """)]);
+    }
+
+    [Fact]
+    public async Task PromoteUsingDirective_ExistingImports()
+    {
+        await VerifyCodeActionAsync(
+            input: """
+                @using [||]System
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            additionalFiles: [
+                (FilePath(@"..\_Imports.razor"), """
+                    @using System.Text
+                    @using Foo.Bar
+                    """)],
+            expected: """
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            codeActionName: LanguageServerConstants.CodeActions.PromoteUsingDirective,
+            additionalExpectedFiles: [
+                (FileUri(@"..\_Imports.razor"), """
+                    @using System.Text
+                    @using Foo.Bar
+                    @using System
+                    """)]);
+    }
+
+    [Fact]
+    public async Task PromoteUsingDirective_ExistingImports_BlankLineAtEnd()
+    {
+        await VerifyCodeActionAsync(
+            input: """
+                @using [||]System
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            additionalFiles: [
+                (FilePath(@"..\_Imports.razor"), """
+                    @using System.Text
+                    @using Foo.Bar
+                    
+                    """)],
+            expected: """
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            codeActionName: LanguageServerConstants.CodeActions.PromoteUsingDirective,
+            additionalExpectedFiles: [
+                (FileUri(@"..\_Imports.razor"), """
+                    @using System.Text
+                    @using Foo.Bar
+                    @using System
+                    """)]);
+    }
+
+    [Fact]
+    public async Task PromoteUsingDirective_ExistingImports_WhitespaceLineAtEnd()
+    {
+        await VerifyCodeActionAsync(
+            input: """
+                @using [||]System
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            additionalFiles: [
+                (FilePath(@"..\_Imports.razor"), """
+                    @using System.Text
+                    @using Foo.Bar
+                        
+                    """)],
+            expected: """
+
+                <div>
+                    Hello World
+                </div>
+                """,
+            codeActionName: LanguageServerConstants.CodeActions.PromoteUsingDirective,
+            additionalExpectedFiles: [
+                (FileUri(@"..\_Imports.razor"), """
+                    @using System.Text
+                    @using Foo.Bar
+                    @using System    
+                    """)]);
+    }
+
     private async Task VerifyCodeActionAsync(TestCode input, string? expected, string codeActionName, int childActionIndex = 0, string? fileKind = null, (string filePath, string contents)[]? additionalFiles = null, (Uri fileUri, string contents)[]? additionalExpectedFiles = null)
     {
         var fileSystem = (RemoteFileSystem)OOPExportProvider.GetExportedValue<IFileSystem>();
@@ -905,7 +1051,7 @@ public class CohostCodeActionsEndpointTest(ITestOutputHelper testOutputHelper) :
         await VerifyCodeActionResultAsync(document, workspaceEdit, expected, additionalExpectedFiles);
     }
 
-    private async Task<CodeAction?> VerifyCodeActionRequestAsync(CodeAnalysis.TextDocument document, TestCode input, string codeActionName, int childActionIndex)
+    private async Task<CodeAction?> VerifyCodeActionRequestAsync(TextDocument document, TestCode input, string codeActionName, int childActionIndex)
     {
         var requestInvoker = new TestLSPRequestInvoker();
         var endpoint = new CohostCodeActionsEndpoint(RemoteServiceInvoker, ClientCapabilitiesService, TestHtmlDocumentSynchronizer.Instance, requestInvoker, NoOpTelemetryReporter.Instance);

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

@@ -272,5 +272,5 @@ public abstract class CohostEndpointTestBase(ITestOutputHelper testOutputHelper)
         => new(FilePath(projectRelativeFileName));
 
     protected static string FilePath(string projectRelativeFileName)
-        => Path.Combine(TestProjectData.SomeProjectPath, projectRelativeFileName);
+        => Path.GetFullPath(Path.Combine(TestProjectData.SomeProjectPath, projectRelativeFileName));
 }