MSTEST0003: Add code fix

src/Analyzers/MSTest.Analyzers.CodeFixes/CodeFixResources.resx

@@ -129,4 +129,7 @@
   <data name="PublicTypeShouldBeTestClassFix" xml:space="preserve">
     <value>Add '[TestClass]'</value>
   </data>
+  <data name="TestMethodShouldBeValidFix" xml:space="preserve">
+    <value>Fix test method signature</value>
+  </data>
 </root>

src/Analyzers/MSTest.Analyzers.CodeFixes/TestMethodShouldBeValidCodeFix.cs

@@ -0,0 +1,137 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Collections.Immutable;
+using System.Composition;
+
+using Analyzer.Utilities;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Editing;
+using Microsoft.CodeAnalysis.Text;
+
+using MSTest.Analyzers.Helpers;
+
+namespace MSTest.Analyzers;
+
+[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(TestMethodShouldBeValidCodeFixProvider))]
+[Shared]
+public sealed class TestMethodShouldBeValidCodeFixProvider : CodeFixProvider
+{
+    public override ImmutableArray<string> FixableDiagnosticIds
+        => ImmutableArray.Create(DiagnosticIds.TestMethodShouldBeValidRuleId);
+
+    public override FixAllProvider GetFixAllProvider()
+        // See https://github.com/dotnet/roslyn/blob/main/docs/analyzers/FixAllProvider.md for more information on Fix All Providers
+        => WellKnownFixAllProviders.BatchFixer;
+
+    public override async Task RegisterCodeFixesAsync(CodeFixContext context)
+    {
+        SyntaxNode root = await context.Document.GetRequiredSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+
+        Diagnostic diagnostic = context.Diagnostics[0];
+        TextSpan diagnosticSpan = diagnostic.Location.SourceSpan;
+
+        SyntaxToken syntaxToken = root.FindToken(diagnosticSpan.Start);
+        if (syntaxToken.Parent is null)
+        {
+            return;
+        }
+
+        // Find the method declaration identified by the diagnostic.
+        MethodDeclarationSyntax methodDeclaration = syntaxToken.Parent.AncestorsAndSelf().OfType<MethodDeclarationSyntax>().First();
+
+        context.RegisterCodeFix(
+            CodeAction.Create(
+                title: CodeFixResources.TestMethodShouldBeValidFix,
+                createChangedSolution: c => FixTestMethodAsync(context.Document, methodDeclaration, c),
+                equivalenceKey: nameof(TestMethodShouldBeValidCodeFixProvider)),
+            diagnostic);
+    }
+
+    private static async Task<Solution> FixTestMethodAsync(Document document, MethodDeclarationSyntax methodDeclaration, CancellationToken cancellationToken)
+    {
+        DocumentEditor editor = await DocumentEditor.CreateAsync(document, cancellationToken).ConfigureAwait(false);
+
+        MethodDeclarationSyntax newMethodDeclaration = methodDeclaration;
+
+        // Remove static modifier if present.
+        SyntaxToken staticModifier = newMethodDeclaration.Modifiers.FirstOrDefault(m => m.IsKind(SyntaxKind.StaticKeyword));
+        if (staticModifier != default)
+        {
+            newMethodDeclaration = newMethodDeclaration.WithModifiers(newMethodDeclaration.Modifiers.Remove(staticModifier));
+        }
+
+        // Remove abstract modifier if present and ensure the method has a body.
+        SyntaxToken abstractModifier = newMethodDeclaration.Modifiers.FirstOrDefault(m => m.IsKind(SyntaxKind.AbstractKeyword));
+        if (abstractModifier != default)
+        {
+            newMethodDeclaration = newMethodDeclaration.WithModifiers(newMethodDeclaration.Modifiers.Remove(abstractModifier));
+            if (newMethodDeclaration.Body == null)
+            {
+                newMethodDeclaration = newMethodDeclaration.WithBody(SyntaxFactory.Block()).WithSemicolonToken(default);
+            }
+        }
+
+        // Remove type parameters to make the method non-generic.
+        if (newMethodDeclaration.TypeParameterList != null)
+        {
+            newMethodDeclaration = newMethodDeclaration.WithTypeParameterList(null);
+        }
+
+        // Ensure the method has public visibility.
+        SyntaxToken publicModifier = newMethodDeclaration.Modifiers.FirstOrDefault(m => m.IsKind(SyntaxKind.PublicKeyword));
+        if (publicModifier == default)
+        {
+            newMethodDeclaration = newMethodDeclaration.WithModifiers(SyntaxFactory.TokenList(SyntaxFactory.Token(SyntaxKind.PublicKeyword)));
+        }
+
+        // Ensure the method returns void or Task/ValueTask.
+        SemanticModel? semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
+        if (semanticModel is not null)
+        {
+            Compilation compilation = semanticModel.Compilation;
+            var wellKnownTypeProvider = WellKnownTypeProvider.GetOrCreate(semanticModel.Compilation);
+            INamedTypeSymbol? taskSymbol = wellKnownTypeProvider.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemThreadingTasksTask);
+            INamedTypeSymbol? valueTaskSymbol = wellKnownTypeProvider.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemThreadingTasksValueTask);
+
+            if (newMethodDeclaration.ReturnType != null &&
+                !newMethodDeclaration.ReturnType.IsVoid() &&
+                (taskSymbol == null || !semanticModel.ClassifyConversion(newMethodDeclaration.ReturnType, taskSymbol).IsImplicit) &&
+                (valueTaskSymbol == null || !semanticModel.ClassifyConversion(newMethodDeclaration.ReturnType, valueTaskSymbol).IsImplicit))
+            {
+                // Change return type to void and remove return statements
+                newMethodDeclaration = newMethodDeclaration.WithReturnType(SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.VoidKeyword)));
+
+                if (newMethodDeclaration.Body != null)
+                {
+                    SyntaxList<StatementSyntax> statements = newMethodDeclaration.Body.Statements;
+                    IEnumerable<StatementSyntax> newStatements = statements.Where(s => s is not ReturnStatementSyntax);
+                    newMethodDeclaration = newMethodDeclaration.WithBody(newMethodDeclaration.Body.WithStatements(SyntaxFactory.List(newStatements)));
+                }
+            }
+        }
+
+        // Ensure async methods do not return void.
+        bool asyncModifier = newMethodDeclaration.Modifiers.Any(m => m.IsKind(SyntaxKind.AsyncKeyword));
+        if (asyncModifier && newMethodDeclaration.ReturnType != null && newMethodDeclaration.ReturnType.IsVoid())
+        {
+            // Change the return type to Task
+            newMethodDeclaration = newMethodDeclaration.WithReturnType(SyntaxFactory.ParseTypeName("Task "));
+        }
+
+        // Apply changes.
+        editor.ReplaceNode(methodDeclaration, newMethodDeclaration);
+        Document newDocument = editor.GetChangedDocument();
+        return newDocument.Project.Solution;
+    }
+}
+
+internal static class TypeSyntaxExtensions
+{
+    public static bool IsVoid(this TypeSyntax typeSyntax) => typeSyntax is PredefinedTypeSyntax predefined && predefined.Keyword.IsKind(SyntaxKind.VoidKeyword);
+}

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.cs.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.de.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.es.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.fr.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.it.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.ja.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.ko.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.pl.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.pt-BR.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.ru.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.tr.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.zh-Hans.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Analyzers/MSTest.Analyzers.CodeFixes/xlf/CodeFixResources.zh-Hant.xlf

@@ -22,6 +22,11 @@
         <target state="new">Add '[TestClass]'</target>
         <note />
       </trans-unit>
+      <trans-unit id="TestMethodShouldBeValidFix">
+        <source>Fix test method signature</source>
+        <target state="new">Fix test method signature</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>