Do not trigger analyzer if arguments are open generics (#117)

Author: viceroypenguin

src/Immediate.Handlers.Analyzers/InvalidIHandlerAnalyzer.cs

@@ -46,6 +46,12 @@ private void AnalyzeMethod(SymbolAnalysisContext context)
 			if (!type.IsIHandler())
 				continue;
 
+			if (type.TypeArguments[0].TypeKind is TypeKind.TypeParameter
+				|| type.TypeArguments[1].TypeKind is TypeKind.TypeParameter)
+			{
+				continue;
+			}
+
 			var hasConcrete = context.Compilation
 				.GetSymbolsWithName("Handler", SymbolFilter.Type, context.CancellationToken)
 				.Any(h =>
@@ -60,8 +66,8 @@ h is INamedTypeSymbol handler
 				Diagnostic.Create(
 					IHandlerMissingImplementation,
 					parameter.Locations[0],
-					type.TypeParameters[0].ToDisplayString(),
-					type.TypeParameters[1].ToDisplayString()
+					type.TypeArguments[0].ToDisplayString(),
+					type.TypeArguments[1].ToDisplayString()
 				)
 			);
 		}

tests/Immediate.Handlers.Tests/AnalyzerTests/InvalidIHandlerAnalyzerTests.cs

@@ -67,4 +67,31 @@ private static ValueTask<Response> HandleAsync(
 			""",
 			DriverReferenceAssemblies.Normal
 		).RunAsync();
+
+	[Fact]
+	public async Task AnalyzerDoesNotTriggerForGenericParameter() =>
+		await AnalyzerTestHelpers.CreateAnalyzerTest<InvalidIHandlerAnalyzer>(
+			"""
+			using System;
+			using System.Collections.Generic;
+			using System.IO;
+			using System.Linq;
+			using System.Net.Http;
+			using System.Threading;
+			using System.Threading.Tasks;
+			using Immediate.Handlers.Shared;
+
+			public static class Test<TRequest>
+			{
+				public static void Method(IHandler<TRequest, int> handler)
+				{
+				}
+
+				public static void Method<TResponse>(IHandler<int, TResponse> handler)
+				{
+				}
+			}
+			""",
+			DriverReferenceAssemblies.Normal
+		).RunAsync();
 }