Add MEN019 exclusion for JSInvokable methods

Author: menees

src/Directory.Build.props

@@ -21,7 +21,7 @@
 		<AssemblyOriginatorKeyFile>../Analyzers.snk</AssemblyOriginatorKeyFile>
 
 		<!-- NOTE: Change the version in Vsix\source.extension.vsixmanifest to match this! -->
-		<Version>3.3.4</Version>
+		<Version>3.3.5</Version>
 
 		<RoslynVersion>3.11.0</RoslynVersion>
 	</PropertyGroup>

src/Menees.Analyzers.Vsix/source.extension.vsixmanifest

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <PackageManifest Version="2.0.0" xmlns="http://schemas.microsoft.com/developer/vsx-schema/2011" xmlns:d="http://schemas.microsoft.com/developer/vsx-schema-design/2011">
     <Metadata>
-        <Identity Id="Menees.Analyzers.Vsix" Version="3.3.4" Language="en-US" Publisher="Bill Menees"/>
+        <Identity Id="Menees.Analyzers.Vsix" Version="3.3.5" Language="en-US" Publisher="Bill Menees"/>
         <DisplayName>Menees.Analyzers.Vsix</DisplayName>
         <Description xml:space="preserve">Provides analyzers for validating that tabs are used for indentation, that the lengths of lines, methods, properties, and files are acceptable, and that #regions are used within long files and files that contain multiple types.</Description>
         <License>License.txt</License>

src/Menees.Analyzers/Men019SupportAsyncCancellationToken.cs

@@ -64,7 +64,8 @@ private sealed class NestedAnalyzer(
 		INamedTypeSymbol cancellationTokenType,
 		INamedTypeSymbol[] fixedTaskTypes,
 		INamedTypeSymbol[] genericTaskTypes,
-		INamedTypeSymbol asyncMethodBuilderAttributeType)
+		INamedTypeSymbol asyncMethodBuilderAttributeType,
+		INamedTypeSymbol? jsInvokableAttributeType)
 	{
 		#region Private Data Members
 
@@ -73,6 +74,7 @@ private sealed class NestedAnalyzer(
 		private readonly INamedTypeSymbol[] fixedTaskTypes = fixedTaskTypes;
 		private readonly INamedTypeSymbol[] genericTaskTypes = genericTaskTypes;
 		private readonly INamedTypeSymbol asyncMethodBuilderAttributeType = asyncMethodBuilderAttributeType;
+		private readonly INamedTypeSymbol? jsInvokableAttributeType = jsInvokableAttributeType;
 		private readonly ConcurrentDictionary<(ITypeSymbol Source, ITypeSymbol Target), bool> canAccessCancellationTokenProperty
 			= new(TypeAccessComparer.Instance);
 
@@ -89,9 +91,13 @@ private sealed class NestedAnalyzer(
 			INamedTypeSymbol? valueTask1Type = compilation.GetTypeByMetadataName(typeof(ValueTask<>).FullName);
 			INamedTypeSymbol? asyncMethodBuilderAttributeType = compilation.GetTypeByMetadataName(typeof(AsyncMethodBuilderAttribute).FullName);
 
+			// This may be null if the project doesn't reference Microsoft.JSInterop.
+			// That's fine; the HasJSInvokableAttribute check will simply be skipped.
+			INamedTypeSymbol? jsInvokableAttributeType = compilation.GetTypeByMetadataName("Microsoft.JSInterop.JSInvokableAttribute");
+
 			NestedAnalyzer? result = cancellationTokenType != null && taskType != null && task1Type != null
 					&& valueTaskType != null && valueTask1Type != null && asyncMethodBuilderAttributeType != null
-				? new(caller, cancellationTokenType, [taskType, valueTaskType], [task1Type, valueTask1Type], asyncMethodBuilderAttributeType)
+				? new(caller, cancellationTokenType, [taskType, valueTaskType], [task1Type, valueTask1Type], asyncMethodBuilderAttributeType, jsInvokableAttributeType)
 				: null;
 			return result;
 		}
@@ -134,7 +140,8 @@ public void HandleNamedTypeSymbol(SymbolAnalysisContext context)
 						&& method.ExplicitInterfaceImplementations.IsDefaultOrEmpty
 						&& !IsImplicitInterfaceImplementation(method)
 						&& !settings.IsUnitTestMethod(method)
-						&& !IsAssemblyEntryPoint(method, ref context))
+						&& !IsAssemblyEntryPoint(method, ref context)
+						&& !HasJSInvokableAttribute(method))
 					{
 						eligibleMethods.Add(method);
 
@@ -263,6 +270,15 @@ private bool IsImplicitInterfaceImplementation(IMethodSymbol method)
 			return result;
 		}
 
+		private bool HasJSInvokableAttribute(IMethodSymbol method)
+		{
+			// JSInvokable methods in Blazor must be public and are called from JavaScript.
+			// JavaScript can't pass a CancellationToken.
+			bool result = this.jsInvokableAttributeType != null
+				&& method.GetAttributes().Any(attr => SymbolComparer.Equals(attr.AttributeClass, this.jsInvokableAttributeType));
+			return result;
+		}
+
 		private static bool IsAssemblyEntryPoint(IMethodSymbol method, ref SymbolAnalysisContext context)
 		{
 			bool result = method.IsStatic

tests/Menees.Analyzers.Test/Men019UnitTests.cs

@@ -77,7 +77,12 @@ private class Nested
 
 	protected override CodeFixProvider? CSharpCodeFixProvider => new Men019SupportAsyncCancellationTokenFixer();
 
-	protected override IEnumerable<Type> AssemblyRequiredTypes => [typeof(ValueTask), typeof(TestMethodAttribute)];
+	protected override IEnumerable<Type> AssemblyRequiredTypes =>
+#if NET
+		[typeof(ValueTask), typeof(TestMethodAttribute), typeof(Microsoft.JSInterop.JSInvokableAttribute)];
+#else
+		[typeof(ValueTask), typeof(TestMethodAttribute)];
+#endif
 
 	#endregion
 
@@ -165,6 +170,38 @@ public sealed class DerivedJob : Job
 
 	#endregion
 
+#if NET
+	#region ValidJSInvokableCodeTest
+
+	[TestMethod]
+	public void ValidJSInvokableCodeTest()
+	{
+		string test = @"using System;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.JSInterop;
+
+public class BlazorComponent
+{
+	[JSInvokable]
+	public Task NotifyFromJs() => Task.CompletedTask;
+
+	[JSInvokable(""CustomIdentifier"")]
+	public Task<string> GetDataForJs() => Task.FromResult(""data"");
+
+	[JSInvokable]
+	public ValueTask<int> ComputeForJs() => new(42);
+}
+"
+		+ SharedCode;
+
+		this.VerifyCSharpDiagnostic(test);
+	}
+
+	#endregion
+#endif
+
 	#region InvalidCodeTest
 
 	[TestMethod]

tests/Menees.Analyzers.Test/Menees.Analyzers.Test.csproj

@@ -17,6 +17,10 @@
 		<None Include="..\Directory.runsettings" Link="Directory.runsettings" />
 	</ItemGroup>
 
+	<ItemGroup Condition="'$(TargetFramework)' == 'net8.0'">
+		<PackageReference Include="Microsoft.JSInterop" Version="8.0.0" />
+	</ItemGroup>
+
 	<ItemGroup>
 		<ProjectReference Include="..\..\src\Menees.Analyzers.CodeFixes\Menees.Analyzers.CodeFixes.csproj" />
 	</ItemGroup>