Merge pull request #30074 from Neme12/fixInterpolatedVerbatimString

Command handler to replace `@$"` with `$@"` when typing interpolated verbatim string

src/EditorFeatures/CSharp/CSharpEditorResources.Designer.cs

@@ -60,6 +60,15 @@ internal class CSharpEditorResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Fix interpolated verbatim string.
+        /// </summary>
+        internal static string Fix_interpolated_verbatim_string {
+            get {
+                return ResourceManager.GetString("Fix_interpolated_verbatim_string", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to      (Press TAB to insert).
         /// </summary>

src/EditorFeatures/CSharp/CSharpEditorResources.resx

@@ -117,6 +117,9 @@
   <resheader name="writer">
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
+  <data name="Fix_interpolated_verbatim_string" xml:space="preserve">
+    <value>Fix interpolated verbatim string</value>
+  </data>
   <data name="Press_TAB_to_insert" xml:space="preserve">
     <value>     (Press TAB to insert)</value>
   </data>

src/EditorFeatures/CSharp/FixInterpolatedVerbatimString/FixInterpolatedVerbatimStringCommandHandler.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.ComponentModel.Composition;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
+using Microsoft.CodeAnalysis.Text;
+using Microsoft.VisualStudio.Commanding;
+using Microsoft.VisualStudio.Text;
+using Microsoft.VisualStudio.Text.Editor.Commanding.Commands;
+using Microsoft.VisualStudio.Utilities;
+using VSCommanding = Microsoft.VisualStudio.Commanding;
+
+namespace Microsoft.CodeAnalysis.Editor.CSharp.FixInterpolatedVerbatimString
+{
+    /// <summary>
+    /// Replaces <c>@$"</c> with <c>$@"</c>, which is the preferred and until C# 8.0 the only supported form
+    /// of an interpolated verbatim string start token. In C# 8.0 we still auto-correct to this form for consistency.
+    /// </summary>
+    [Export(typeof(VSCommanding.ICommandHandler))]
+    [ContentType(ContentTypeNames.CSharpContentType)]
+    [Name(nameof(FixInterpolatedVerbatimStringCommandHandler))]
+    internal sealed class FixInterpolatedVerbatimStringCommandHandler : IChainedCommandHandler<TypeCharCommandArgs>
+    {
+        public string DisplayName => CSharpEditorResources.Fix_interpolated_verbatim_string;
+
+        public void ExecuteCommand(TypeCharCommandArgs args, Action nextCommandHandler, CommandExecutionContext executionContext)
+        {
+            // We need to check for the token *after* the opening quote is typed, so defer to the editor first
+            nextCommandHandler();
+
+            if (args.TypedChar == '"')
+            {
+                var caret = args.TextView.GetCaretPoint(args.SubjectBuffer);
+                if (caret != null)
+                {
+                    var position = caret.Value.Position;
+                    var snapshot = caret.Value.Snapshot;
+
+                    if (position >= 3 &&
+                        snapshot[position - 1] == '"' &&
+                        snapshot[position - 2] == '$' &&
+                        snapshot[position - 3] == '@')
+                    {
+                        var document = snapshot.GetOpenDocumentInCurrentContextWithChanges();
+                        if (document != null)
+                        {
+                            var root = document.GetSyntaxRootSynchronously(executionContext.OperationContext.UserCancellationToken);
+                            var token = root.FindToken(position - 3);
+                            if (token.IsKind(SyntaxKind.InterpolatedVerbatimStringStartToken))
+                            {
+                                args.SubjectBuffer.Replace(new Span(position - 3, 2), "$@");
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        public VSCommanding.CommandState GetCommandState(TypeCharCommandArgs args, Func<VSCommanding.CommandState> nextCommandHandler)
+            => nextCommandHandler();
+    }
+}

src/EditorFeatures/CSharp/SplitStringLiteral/SplitStringLiteralCommandHandler.cs

-using System.ComponentModel.Composition;
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.ComponentModel.Composition;
 using System.Threading;
 using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
 using Microsoft.CodeAnalysis.Editor.Shared.Utilities;

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.cs.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="cs" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Pro vložení stiskněte TAB.)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.de.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="de" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Zum Einfügen TAB-TASTE drücken)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.es.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="es" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Presione TAB para insertar)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.fr.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="fr" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Appuyez sur TAB pour insérer)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.it.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="it" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Premere TAB per inserire)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.ja.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="ja" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">(Tab キーを押して挿入)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.ko.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="ko" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (삽입하려면 &lt;Tab&gt; 키 누름)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.pl.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="pl" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Naciśnij klawisz TAB, aby wstawić)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.pt-BR.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="pt-BR" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Pressione TAB para inserir)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.ru.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="ru" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Нажмите клавишу TAB для вставки)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.tr.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="tr" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (Eklemek için TAB tuşuna basın)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.zh-Hans.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="zh-Hans" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">(按 Tab 插入)</target>

src/EditorFeatures/CSharp/xlf/CSharpEditorResources.zh-Hant.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="zh-Hant" original="../CSharpEditorResources.resx">
     <body>
+      <trans-unit id="Fix_interpolated_verbatim_string">
+        <source>Fix interpolated verbatim string</source>
+        <target state="new">Fix interpolated verbatim string</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Press_TAB_to_insert">
         <source>     (Press TAB to insert)</source>
         <target state="translated">     (按 TAB 鍵插入)</target>

src/EditorFeatures/CSharpTest/FixInterpolatedVerbatimString/FixInterpolatedVerbatimStringCommandHandlerTests.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Immutable;
+using System.Linq;
+using Microsoft.CodeAnalysis.Editor.CSharp.FixInterpolatedVerbatimString;
+using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
+using Microsoft.CodeAnalysis.Editor.UnitTests.Utilities;
+using Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces;
+using Microsoft.CodeAnalysis.Test.Utilities;
+using Microsoft.CodeAnalysis.Text;
+using Microsoft.CodeAnalysis.Text.Shared.Extensions;
+using Microsoft.VisualStudio.Text.Editor.Commanding.Commands;
+using Microsoft.VisualStudio.Text.Operations;
+using Roslyn.Test.Utilities;
+using Xunit;
+
+namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.FixInterpolatedVerbatimString
+{
+    [UseExportProvider]
+    public class FixInterpolatedVerbatimStringCommandHandlerTests
+    {
+        private static TestWorkspace CreateTestWorkspace(string inputMarkup)
+        {
+            var workspace = TestWorkspace.CreateCSharp(inputMarkup);
+            var document = workspace.Documents.Single();
+            var view = document.GetTextView();
+            view.SetSelection(document.SelectedSpans.Single().ToSnapshotSpan(view.TextBuffer.CurrentSnapshot));
+            return workspace;
+        }
+
+        private static (string quoteCharSnapshotText, int quoteCharCaretPosition) TypeQuoteChar(TestWorkspace workspace)
+        {
+            var view = workspace.Documents.Single().GetTextView();
+            var commandHandler = new FixInterpolatedVerbatimStringCommandHandler();
+
+            string quoteCharSnapshotText = default;
+            int quoteCharCaretPosition = default;
+
+            commandHandler.ExecuteCommand(new TypeCharCommandArgs(view, view.TextBuffer, '"'),
+                () =>
+                {
+                    var editorOperations = workspace.GetService<IEditorOperationsFactoryService>().GetEditorOperations(view);
+                    editorOperations.InsertText("\"");
+
+                    quoteCharSnapshotText = view.TextBuffer.CurrentSnapshot.GetText();
+                    quoteCharCaretPosition = view.Caret.Position.BufferPosition.Position;
+
+                }, TestCommandExecutionContext.Create());
+
+            return (quoteCharSnapshotText, quoteCharCaretPosition);
+        }
+
+        private static void TestHandled(string inputMarkup, string expectedOutputMarkup)
+        {
+            using (var workspace = CreateTestWorkspace(inputMarkup))
+            {
+                var (quoteCharSnapshotText, quoteCharCaretPosition) = TypeQuoteChar(workspace);
+                var view = workspace.Documents.Single().GetTextView();
+
+                MarkupTestFile.GetSpans(expectedOutputMarkup,
+                    out var expectedOutput, out ImmutableArray<TextSpan> expectedSpans);
+
+                Assert.Equal(expectedOutput, view.TextBuffer.CurrentSnapshot.GetText());
+                Assert.Equal(expectedSpans.Single().Start, view.Caret.Position.BufferPosition.Position);
+ 
+                var history = workspace.GetService<ITextUndoHistoryRegistry>().GetHistory(view.TextBuffer);
+                history.Undo(count: 1);
+
+                // Ensure that after undo, the ordering fix is undone but the quote remains inserted
+                Assert.Equal(quoteCharSnapshotText, view.TextBuffer.CurrentSnapshot.GetText());
+                Assert.Equal(quoteCharCaretPosition, view.Caret.Position.BufferPosition.Position);
+            }
+        }
+
+        private static void TestNotHandled(string inputMarkup)
+        {
+            using (var workspace = CreateTestWorkspace(inputMarkup))
+            {
+                var originalView = workspace.Documents.Single().GetTextView();
+                var originalSnapshotText = originalView.TextBuffer.CurrentSnapshot.GetText();
+                var originalCaretPosition = originalView.Caret.Position.BufferPosition.Position;
+
+                var (quoteCharSnapshotText, quoteCharCaretPosition) = TypeQuoteChar(workspace);
+                var view = workspace.Documents.Single().GetTextView();
+
+                Assert.Equal(quoteCharSnapshotText, view.TextBuffer.CurrentSnapshot.GetText());
+                Assert.Equal(quoteCharCaretPosition, view.Caret.Position.BufferPosition.Position);
+
+                var history = workspace.GetService<ITextUndoHistoryRegistry>().GetHistory(view.TextBuffer);
+                history.Undo(count: 1);
+
+                // Ensure that after undo, the quote is removed because the command made no changes
+                Assert.Equal(originalSnapshotText, view.TextBuffer.CurrentSnapshot.GetText());
+                Assert.Equal(originalCaretPosition, view.Caret.Position.BufferPosition.Position);
+            }
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestAfterAtSignDollarSign()
+        {
+            TestHandled(
+@"class C
+{
+    void M()
+    {
+        var v = @$[||]
+    }
+}",
+@"class C
+{
+    void M()
+    {
+        var v = $@""[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingAfterDollarSignAtSign()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = $@[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingAfterAtSign()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = @[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingAfterDollarSign()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = $[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInEmptyFileAfterAtSignDollarSign()
+        {
+            TestNotHandled(@"@$[||]");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInEmptyFileAfterDollarSign()
+        {
+            TestNotHandled(@"$[||]");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInEmptyFile()
+        {
+            TestNotHandled(@"[||]");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestAfterAtSignDollarSignEndOfFile()
+        {
+            TestHandled(
+@"class C
+{
+    void M()
+    {
+        var v = @$[||]",
+@"class C
+{
+    void M()
+    {
+        var v = $@""[||]");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInClassDeclaration()
+        {
+            TestNotHandled(
+@"class C
+{
+    @$[||]
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInComment1()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = // @$[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInComment2()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = /* @$[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInString()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = ""@$[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInVerbatimString()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = @""@$[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInInterpolatedString()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = $""@$[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInInterpolatedVerbatimString1()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = $@""@$[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestMissingInInterpolatedVerbatimString2()
+        {
+            TestNotHandled(
+@"class C
+{
+    void M()
+    {
+        var v = @$""@$[||]
+    }
+}");
+        }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.FixInterpolatedVerbatimString)]
+        public void TestTrivia()
+        {
+            TestHandled(
+@"class C
+{
+    void M()
+    {
+        var v = // a
+                /* b */ @$[||] // c
+    }
+}",
+@"class C
+{
+    void M()
+    {
+        var v = // a
+                /* b */ $@""[||] // c
+    }
+}");
+        }
+    }
+}

src/EditorFeatures/CSharpTest/SplitStringLiteral/SplitStringLiteralCommandHandlerTests.cs

-using System;
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
 using System.Collections.Immutable;
 using System.Linq;
 using Microsoft.CodeAnalysis.Editor.CSharp.SplitStringLiteral;

src/Test/Utilities/Portable/Traits/Traits.cs

@@ -179,6 +179,7 @@ public static class Features
             public const string F1Help = nameof(F1Help);
             public const string FindReferences = nameof(FindReferences);
             public const string FixIncorrectTokens = nameof(FixIncorrectTokens);
+            public const string FixInterpolatedVerbatimString = nameof(FixInterpolatedVerbatimString);
             public const string Formatting = nameof(Formatting);
             public const string GoToDefinition = nameof(GoToDefinition);
             public const string GoToImplementation = nameof(GoToImplementation);

src/VisualStudio/IntegrationTest/IntegrationTests/CSharp/CSharpAutomaticBraceCompletion.cs

@@ -200,6 +200,38 @@ class C {
             VisualStudio.Editor.Verify.CurrentLineText("string str = \"Hi Roslyn!\"$$", assertCaretPosition: true);
         }
 
+        [WpfFact, Trait(Traits.Feature, Traits.Features.AutomaticCompletion)]
+        public void DoubleQuote_FixedInterpolatedVerbatimString()
+        {
+            SetUpEditor(@"
+class C
+{
+    void M()
+    {
+        $$
+    }
+}");
+
+            VisualStudio.Editor.SendKeys("var v = @$\"");
+            VisualStudio.Editor.Verify.CurrentLineText("var v = $@\"$$\"", assertCaretPosition: true);
+
+            // Backspace removes quotes
+            VisualStudio.Editor.SendKeys(VirtualKey.Backspace);
+            VisualStudio.Editor.Verify.CurrentLineText("var v = $@$$", assertCaretPosition: true);
+
+            // Undo puts them back
+            VisualStudio.Editor.Undo();
+            VisualStudio.Editor.Verify.CurrentLineText("var v = $@\"$$\"", assertCaretPosition: true);
+
+            // First, the FixInterpolatedVerbatimString action is undone (@$ reordering)
+            VisualStudio.Editor.Undo();
+            VisualStudio.Editor.Verify.CurrentLineText("var v = @$\"$$\"", assertCaretPosition: true);
+
+            // Then the automatic quote completion is undone
+            VisualStudio.Editor.Undo();
+            VisualStudio.Editor.Verify.CurrentLineText("var v = @$\"$$", assertCaretPosition: true);
+        }
+
         [WpfFact, Trait(Traits.Feature, Traits.Features.AutomaticCompletion)]
         public void AngleBracket_PossibleGenerics_InsertionAndCompletion()
         {