Improved support and tests for out parameters

Author: sharwell

AsyncUsageAnalyzers/AsyncUsageAnalyzers.Test/Usage/IncludeCancellationParameterUnitTests.cs

@@ -61,6 +61,26 @@ private async Task Method2Async() { }
             await this.VerifyCSharpDiagnosticAsync(testCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
         }
 
+        [Fact]
+        public async Task TestCancellationTokenIsOutParameterAsync()
+        {
+            string testCode = @"
+using System.Threading;
+using System.Threading.Tasks;
+class ClassName
+{
+    public Task MethodAsync(out CancellationToken cancellationToken)
+    {
+        cancellationToken = CancellationToken.None;
+        return Task.FromResult(0);
+    }
+}
+";
+
+            var expected = this.CSharpDiagnostic().WithArguments("MethodAsync").WithLocation(6, 17);
+            await this.VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
+        }
+
         [Fact]
         public async Task TestCancellationTokenInStructureAsync()
         {
@@ -165,6 +185,31 @@ struct Context
             await this.VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
         }
 
+        [Fact]
+        public async Task TestContextStructureIsOutParameterAsync()
+        {
+            string testCode = @"
+using System.Threading;
+using System.Threading.Tasks;
+class ClassName
+{
+    public Task MethodAsync(out Context context)
+    {
+        context = default(Context);
+        return Task.FromResult(0);
+    }
+}
+
+struct Context
+{
+    public CancellationToken CancellationToken { get; }
+}
+";
+
+            var expected = this.CSharpDiagnostic().WithArguments("MethodAsync").WithLocation(6, 17);
+            await this.VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
+        }
+
         [Fact]
         public async Task TestCancellationTokenInInterfaceAsync()
         {

AsyncUsageAnalyzers/AsyncUsageAnalyzers/Usage/IncludeCancellationParameterAnalyzer.cs

@@ -100,6 +100,11 @@ public void HandleMethodDeclaration(SymbolAnalysisContext context)
 
                 foreach (var parameterSymbol in symbol.Parameters)
                 {
+                    if (parameterSymbol.RefKind == RefKind.Out)
+                    {
+                        continue;
+                    }
+
                     INamedTypeSymbol parameterType = parameterSymbol.Type as INamedTypeSymbol;
                     if (this.cancellationTokenType.Equals(parameterType))
                     {