Fixer now supports explicit param name prefix when adding 1 parameter…

… to the invocation is not in the right position
Particular · Apr 28, 2021 · 7aed0fb · 7aed0fb
1 parent 1abc15d
commit 7aed0fb
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Showing 3 changed files with 67 additions and 8 deletions.
diff --git a/...iceBus.Core.Analyzer.Tests/ForwardCancellationToken/ForwardCancellationTokenFixerTests.cs b/...iceBus.Core.Analyzer.Tests/ForwardCancellationToken/ForwardCancellationTokenFixerTests.cs
@@ -215,6 +215,44 @@ public class TestMessage : ICommand {}
             return VerifyFix(test, fixedTest);
         }
 
+        [Test]
+        public Task MultipleOptionalParameters()
+        {
+            var test = @"
+using NServiceBus;
+using System.Threading;
+using System.Threading.Tasks;
+public class Foo : IHandleMessages<TestMessage>
+{
+    public async Task Handle(TestMessage message, IMessageHandlerContext context)
+    {
+        await TestMethod(1);
+    }
+
+    Task TestMethod(int a, int b = 0, int c = 1, int d = 2, CancellationToken token = default(CancellationToken)) { return Task.CompletedTask; }
+}
+public class TestMessage : ICommand {}
+";
+
+            var fixedTest = @"
+using NServiceBus;
+using System.Threading;
+using System.Threading.Tasks;
+public class Foo : IHandleMessages<TestMessage>
+{
+    public async Task Handle(TestMessage message, IMessageHandlerContext context)
+    {
+        await TestMethod(1, token: context.CancellationToken);
+    }
+
+    Task TestMethod(int a, int b = 0, int c = 1, int d = 2, CancellationToken token = default(CancellationToken)) { return Task.CompletedTask; }
+}
+public class TestMessage : ICommand {}
+";
+
+            return VerifyFix(test, fixedTest);
+        }
+
         protected override DiagnosticAnalyzer GetAnalyzer() => new ForwardCancellationTokenAnalyzer();
 
         protected override CodeFixProvider GetCodeFixProvider() => new ForwardCancellationTokenFixer();

diff --git a/src/NServiceBus.Core.Analyzer/ForwardCancellationTokenAnalyzer.cs b/src/NServiceBus.Core.Analyzer/ForwardCancellationTokenAnalyzer.cs
@@ -141,9 +141,9 @@ static void AnalyzeSyntax(SyntaxNodeAnalysisContext context, KnownTypes knownTyp
                 return;
             }
 
-            if (InvocationMethodTakesAToken(methodSymbol, knownTypes))
+            if (InvocationMethodTakesAToken(methodSymbol, knownTypes, invocationArgs, out var explicitParamName))
             {
-                ReportDiagnostic(context, invocation, contextParamName, methodSymbol);
+                ReportDiagnostic(context, invocation, contextParamName, methodSymbol, explicitParamName);
                 return;
             }
 
@@ -242,8 +242,10 @@ static bool ClassInheritsATargetType(SyntaxNodeAnalysisContext context, ClassDec
                 });
         }
 
-        static bool InvocationMethodTakesAToken(IMethodSymbol method, KnownTypes knownTypes)
+        static bool InvocationMethodTakesAToken(IMethodSymbol method, KnownTypes knownTypes, ArgumentSyntax[] arguments, out string explicitParamName)
         {
+            explicitParamName = null;
+
             // If is an NServiceBus-namespace extension method that extends IMessageHandlerContext, then skip
             if (method.IsExtensionMethod && method.ContainingNamespace?.Name == "NServiceBus")
             {
@@ -265,18 +267,23 @@ static bool InvocationMethodTakesAToken(IMethodSymbol method, KnownTypes knownTy
             // If parameter has a default value being used
             if (lastParameter.Type.Equals(knownTypes.CancellationToken) && lastParameter.IsOptional)
             {
+                if (method.Parameters.Length != arguments.Length + 1)
+                {
+                    explicitParamName = lastParameter.Name;
+                }
                 return true;
             }
 
             return false;
         }
 
-        static void ReportDiagnostic(SyntaxNodeAnalysisContext context, InvocationExpressionSyntax invocation, string contextParamName, IMethodSymbol methodSymbol)
+        static void ReportDiagnostic(SyntaxNodeAnalysisContext context, InvocationExpressionSyntax invocation, string contextParamName, IMethodSymbol methodSymbol, string explicitParamName = null)
         {
             var properties = new Dictionary<string, string>
             {
                 { "ContextParamName", contextParamName },
-                { "MethodName", methodSymbol.Name }
+                { "MethodName", methodSymbol.Name },
+                { "ExplicitParameterName", explicitParamName }
             }.ToImmutableDictionary();
 
             var diagnostic = Diagnostic.Create(ForwardCancellationTokenDiagnostic, invocation.GetLocation(), properties, contextParamName, methodSymbol.Name);

diff --git a/src/NServiceBus.Core.Analyzer/ForwardCancellationTokenFixer.cs b/src/NServiceBus.Core.Analyzer/ForwardCancellationTokenFixer.cs
@@ -27,6 +27,7 @@ public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
             var diagnostic = context.Diagnostics.First();
             var contextVarName = diagnostic.Properties["ContextParamName"];
             var methodName = diagnostic.Properties["MethodName"];
+            var explicitParameterName = diagnostic.Properties["ExplicitParameterName"];
             var sourceLocation = diagnostic.Location;
             var diagnosticSpan = sourceLocation.SourceSpan;
 
@@ -38,13 +39,26 @@ public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
             // Register a code action that will invoke the fix.
             context.RegisterCodeFix(
                 CodeAction.Create(title, ct =>
-                AddCancellationToken(context.Document, invocationSyntax, contextVarName, ct), equivalenceKey: title), diagnostic);
+                AddCancellationToken(context.Document, invocationSyntax, contextVarName, explicitParameterName, ct), equivalenceKey: title), diagnostic);
 
         }
 
-        static async Task<Document> AddCancellationToken(Document document, InvocationExpressionSyntax invocationSyntax, string contextVarName, CancellationToken cancellationToken)
+        static async Task<Document> AddCancellationToken(Document document, InvocationExpressionSyntax invocationSyntax, string contextVarName, string explicitParameterName, CancellationToken cancellationToken)
         {
-            var newArg = SyntaxFactory.Argument(SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, SyntaxFactory.IdentifierName(contextVarName), SyntaxFactory.IdentifierName("CancellationToken")));
+            // The context.CancellationToken part. This is always required.
+            var simpleMemberAccess = SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, SyntaxFactory.IdentifierName(contextVarName), SyntaxFactory.IdentifierName("CancellationToken"));
+
+            ArgumentSyntax newArg;
+            if (explicitParameterName != null)
+            {
+                // Add the prefix `token: context.CancellationToken` if adding 1 argument would not be in the correct location
+                var nameColon = SyntaxFactory.NameColon(SyntaxFactory.IdentifierName(explicitParameterName));
+                newArg = SyntaxFactory.Argument(nameColon, default, simpleMemberAccess);
+            }
+            else
+            {
+                newArg = SyntaxFactory.Argument(simpleMemberAccess);
+            }
             var newArgList = invocationSyntax.ArgumentList.AddArguments(newArg);
 
             var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);