Fix #16: AsyncVoid ignores EventHandlers

semihokur · May 11, 2022 · ecdac26 · ecdac26
1 parent 8bba5a6
commit ecdac26
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Showing 3 changed files with 50 additions and 2 deletions.
diff --git a/AsyncFixer.Test/AsyncVoidTests.cs b/AsyncFixer.Test/AsyncVoidTests.cs
@@ -1,9 +1,12 @@
-using Microsoft.CodeAnalysis;
+using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.Diagnostics;
 using TestHelper;
-using AsyncFixer.AsyncVoid;
 using Xunit;
+using AsyncFixer.AsyncVoid;
+using Verify = AsyncFixer.Test.Helpers.CSharpCodeFixVerifier<
+    AsyncFixer.AsyncVoid.AsyncVoidAnalyzer,
+    AsyncFixer.AsyncVoid.AsyncVoidFixer>;
 
 namespace AsyncFixer.Test
 {
@@ -120,6 +123,29 @@ private static Task ProcessAsync()
             VerifyCSharpFix(test, test);
         }
 
+        [Fact]
+        public Task NoWarn_EventHandler()
+        {
+            //No diagnostics expected to show up
+
+            var test = @"
+using System;
+using System.Threading.Tasks;
+
+class Program
+{
+    public void foo()
+    {
+        AppDomain.CurrentDomain.ProcessExit += async (a, b) =>
+        {
+            await Task.Delay(100);
+        };
+    }
+}";
+
+            return Verify.VerifyAsync(test);
+        }
+
         protected override CodeFixProvider GetCSharpCodeFixProvider()
         {
             return new AsyncVoidFixer();

diff --git a/AsyncFixer/AsyncVoid/AsyncVoidAnalyzer.cs b/AsyncFixer/AsyncVoid/AsyncVoidAnalyzer.cs
@@ -54,6 +54,12 @@ private void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
         private void AnalyzeAnonymousFunction(OperationAnalysisContext context)
         {
             var operation = (IAnonymousFunctionOperation)context.Operation;
+
+            if (operation.IsEventHandler())
+            {
+                return;
+            }
+
             var symbol = operation.Symbol;
             if (symbol == null || !symbol.IsAsync || !symbol.ReturnsVoid)
             {

diff --git a/AsyncFixer/Helpers.cs b/AsyncFixer/Helpers.cs
@@ -3,6 +3,7 @@
 using System.Linq;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Operations;
 
 namespace AsyncFixer
 {
@@ -78,6 +79,21 @@ public static ExpressionSyntax RemoveConfigureAwait(ExpressionSyntax expression)
             return expression;
         }
 
+        public static bool IsEventHandler(this IOperation operation)
+        {
+            while (operation != null)
+            {
+                if (operation is IEventAssignmentOperation)
+                {
+                    return true;
+                }
+
+                operation = operation.Parent;
+            }
+
+            return false;
+        }
+
         public static T FirstAncestorOrSelfUnderGivenNode<T>(this SyntaxNode node, SyntaxNode parent)
             where T : SyntaxNode
         {