fix: resolve IndexOutOfRangeException with MethodDataSource<T> on class (#5118)

TUnit.Core.SourceGenerator.Tests/Bugs/5118/Tests5118.cs

@@ -0,0 +1,16 @@
+
+namespace TUnit.Core.SourceGenerator.Tests.Bugs._5118;
+
+internal class Tests5118 : TestsBase
+{
+    [Test]
+    public Task Test() => RunTest(Path.Combine(Git.RootDirectory.FullName,
+            "TUnit.TestProject",
+            "Bugs",
+            "5118",
+            "AsyncClassMethodDataSourceTests.cs"),
+        async generatedFiles =>
+        {
+            await Assert.That(generatedFiles).HasCount().EqualTo(1);
+        });
+}

TUnit.Core.SourceGenerator.Tests/Tests5118.Test.verified.txt

@@ -0,0 +1,154 @@
+// <auto-generated/>
+#pragma warning disable
+
+#nullable enable
+namespace TUnit.Generated;
+[global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverageAttribute]
+[global::System.CodeDom.Compiler.GeneratedCode("TUnit", "VERSION_SCRUBBED")]
+internal static class TUnit_TestProject_Bugs__5118_AsyncClassMethodDataSourceTests__TestSource
+{
+    public static global::System.Collections.Generic.IReadOnlyList<global::TUnit.Core.TestMetadata> GetTests(string testSessionId)
+    {
+        var __classMetadata = global::TUnit.Core.ClassMetadata.GetOrAdd("TestsBase`1:global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests", new global::TUnit.Core.ClassMetadata
+        {
+            Type = typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests),
+            TypeInfo = new global::TUnit.Core.ConcreteType(typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests)),
+            Name = "AsyncClassMethodDataSourceTests",
+            Namespace = "TUnit.TestProject.Bugs._5118",
+            Assembly = global::TUnit.Core.AssemblyMetadata.GetOrAdd("TestsBase`1", "TestsBase`1"),
+            Parameters = new global::TUnit.Core.ParameterMetadata[]
+            {
+                global::TUnit.Core.ParameterMetadataFactory.Create(typeof(int), "Id", new global::TUnit.Core.ConcreteType(typeof(int)), false, reflectionInfoFactory: static () => typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests).GetConstructor(new global::System.Type[] { typeof(int), typeof(string), typeof(global::System.DateTime) })!.GetParameters()[0]),
+                global::TUnit.Core.ParameterMetadataFactory.Create(typeof(string), "Name", new global::TUnit.Core.ConcreteType(typeof(string)), false, reflectionInfoFactory: static () => typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests).GetConstructor(new global::System.Type[] { typeof(int), typeof(string), typeof(global::System.DateTime) })!.GetParameters()[1]),
+                global::TUnit.Core.ParameterMetadataFactory.Create(typeof(global::System.DateTime), "CreatedAt", new global::TUnit.Core.ConcreteType(typeof(global::System.DateTime)), false, reflectionInfoFactory: static () => typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests).GetConstructor(new global::System.Type[] { typeof(int), typeof(string), typeof(global::System.DateTime) })!.GetParameters()[2])
+            },
+            Properties = global::System.Array.Empty<global::TUnit.Core.PropertyMetadata>(),
+            Parent = null
+        });
+        var __classType = typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests);
+        var metadata_TestWithAsyncComplexData__CancellationToken = global::TUnit.Core.TestMetadataFactory.Create<global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests>(
+            "TestWithAsyncComplexData", "TestWithAsyncComplexData", 22,
+            __InvokeTest_TestWithAsyncComplexData__CancellationToken, __CreateAttributes_0, CreateInstance,
+            global::TUnit.Core.MethodMetadataFactory.Create("TestWithAsyncComplexData", __classType, typeof(global::System.Threading.Tasks.Task), __classMetadata, parameters: new global::TUnit.Core.ParameterMetadata[]
+        {
+        global::TUnit.Core.ParameterMetadataFactory.Create(typeof(global::System.Threading.CancellationToken), "token", new global::TUnit.Core.ConcreteType(typeof(global::System.Threading.CancellationToken)), false, reflectionInfoFactory: static () => typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests).GetMethod("TestWithAsyncComplexData", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] { typeof(global::System.Threading.CancellationToken) }, null)!.GetParameters()[0])
+        }),
+            classDataSources: new global::TUnit.Core.IDataSourceAttribute[]
+        {
+            new global::TUnit.Core.MethodDataSourceAttribute("GetAsyncTestData")
+            {
+                Factory = (dataGeneratorMetadata) =>
+                {
+                    async global::System.Collections.Generic.IAsyncEnumerable<global::System.Func<global::System.Threading.Tasks.Task<object?[]?>>> Factory()
+                    {
+                        var result = global::TUnit.TestProject.Bugs._5118.AsyncTestDataSources.GetAsyncTestData();
+                        await foreach (var item in result)
+                        {
+                            yield return () => global::System.Threading.Tasks.Task.FromResult(global::TUnit.Core.Helpers.DataSourceHelpers.ToObjectArray(item));
+                        }
+                    }
+                    return Factory();
+                }
+            },
+        },
+            testSessionId: testSessionId
+        );
+        return new global::TUnit.Core.TestMetadata[] { metadata_TestWithAsyncComplexData__CancellationToken };
+    }
+    public static global::System.Collections.Generic.IEnumerable<global::TUnit.Core.TestDescriptor> EnumerateTestDescriptors()
+    {
+        yield return new global::TUnit.Core.TestDescriptor
+        {
+            TestId = "TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests.TestWithAsyncComplexData",
+            ClassName = "AsyncClassMethodDataSourceTests",
+            MethodName = "TestWithAsyncComplexData",
+            FullyQualifiedName = "TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests.TestWithAsyncComplexData",
+            FilePath = @"",
+            LineNumber = 22,
+            Categories = global::System.Array.Empty<string>(),
+            Properties = global::System.Array.Empty<string>(),
+            HasDataSource = true,
+            RepeatCount = 0,
+            DependsOn = global::System.Array.Empty<string>(),
+            Materializer = __Materialize_TestWithAsyncComplexData__CancellationToken
+        };
+    }
+    private static global::System.Attribute[] __CreateAttributes_0()
+    {
+        return
+        [
+            new global::TUnit.Core.TestAttribute(),
+            new global::TUnit.Core.TimeoutAttribute(5000),
+            new global::TUnit.TestProject.Attributes.EngineTest(global::TUnit.TestProject.Attributes.ExpectedResult.Pass),
+            new global::TUnit.Core.MethodDataSourceAttribute<global::TUnit.TestProject.Bugs._5118.AsyncTestDataSources>("GetAsyncTestData")
+        ];
+    }
+    private static global::System.Threading.Tasks.ValueTask __InvokeTest_TestWithAsyncComplexData__CancellationToken(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests instance, object?[] args, global::System.Threading.CancellationToken cancellationToken)
+    {
+        try
+        {
+            return new global::System.Threading.Tasks.ValueTask(instance.TestWithAsyncComplexData(cancellationToken));
+        }
+        catch (global::System.Exception ex)
+        {
+            return new global::System.Threading.Tasks.ValueTask(global::System.Threading.Tasks.Task.FromException(ex));
+        }
+    }
+    private static global::System.Collections.Generic.IReadOnlyList<global::TUnit.Core.TestMetadata> __Materialize_TestWithAsyncComplexData__CancellationToken(string testSessionId)
+    {
+        var __classMetadata = global::TUnit.Core.ClassMetadata.GetOrAdd("TestsBase`1:global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests", new global::TUnit.Core.ClassMetadata
+        {
+            Type = typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests),
+            TypeInfo = new global::TUnit.Core.ConcreteType(typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests)),
+            Name = "AsyncClassMethodDataSourceTests",
+            Namespace = "TUnit.TestProject.Bugs._5118",
+            Assembly = global::TUnit.Core.AssemblyMetadata.GetOrAdd("TestsBase`1", "TestsBase`1"),
+            Parameters = new global::TUnit.Core.ParameterMetadata[]
+            {
+                global::TUnit.Core.ParameterMetadataFactory.Create(typeof(int), "Id", new global::TUnit.Core.ConcreteType(typeof(int)), false, reflectionInfoFactory: static () => typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests).GetConstructor(new global::System.Type[] { typeof(int), typeof(string), typeof(global::System.DateTime) })!.GetParameters()[0]),
+                global::TUnit.Core.ParameterMetadataFactory.Create(typeof(string), "Name", new global::TUnit.Core.ConcreteType(typeof(string)), false, reflectionInfoFactory: static () => typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests).GetConstructor(new global::System.Type[] { typeof(int), typeof(string), typeof(global::System.DateTime) })!.GetParameters()[1]),
+                global::TUnit.Core.ParameterMetadataFactory.Create(typeof(global::System.DateTime), "CreatedAt", new global::TUnit.Core.ConcreteType(typeof(global::System.DateTime)), false, reflectionInfoFactory: static () => typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests).GetConstructor(new global::System.Type[] { typeof(int), typeof(string), typeof(global::System.DateTime) })!.GetParameters()[2])
+            },
+            Properties = global::System.Array.Empty<global::TUnit.Core.PropertyMetadata>(),
+            Parent = null
+        });
+        var __classType = typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests);
+        var metadata = global::TUnit.Core.TestMetadataFactory.Create<global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests>(
+            "TestWithAsyncComplexData", "TestWithAsyncComplexData", 22,
+            __InvokeTest_TestWithAsyncComplexData__CancellationToken, __CreateAttributes_0, CreateInstance,
+            global::TUnit.Core.MethodMetadataFactory.Create("TestWithAsyncComplexData", __classType, typeof(global::System.Threading.Tasks.Task), __classMetadata, parameters: new global::TUnit.Core.ParameterMetadata[]
+    {
+    global::TUnit.Core.ParameterMetadataFactory.Create(typeof(global::System.Threading.CancellationToken), "token", new global::TUnit.Core.ConcreteType(typeof(global::System.Threading.CancellationToken)), false, reflectionInfoFactory: static () => typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests).GetMethod("TestWithAsyncComplexData", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] { typeof(global::System.Threading.CancellationToken) }, null)!.GetParameters()[0])
+    }),
+            classDataSources: new global::TUnit.Core.IDataSourceAttribute[]
+    {
+        new global::TUnit.Core.MethodDataSourceAttribute("GetAsyncTestData")
+        {
+            Factory = (dataGeneratorMetadata) =>
+            {
+                async global::System.Collections.Generic.IAsyncEnumerable<global::System.Func<global::System.Threading.Tasks.Task<object?[]?>>> Factory()
+                {
+                    var result = global::TUnit.TestProject.Bugs._5118.AsyncTestDataSources.GetAsyncTestData();
+                    await foreach (var item in result)
+                    {
+                        yield return () => global::System.Threading.Tasks.Task.FromResult(global::TUnit.Core.Helpers.DataSourceHelpers.ToObjectArray(item));
+                    }
+                }
+                return Factory();
+            }
+        },
+    },
+            testSessionId: testSessionId
+        );
+        return new global::TUnit.Core.TestMetadata[] { metadata };
+    }
+    internal static global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests CreateInstance(global::System.Type[] typeArgs, object?[] args)
+    {
+        return new global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests(global::TUnit.Core.Helpers.CastHelper.Cast<int>(args[0]), global::TUnit.Core.Helpers.CastHelper.Cast<string>(args[1]), global::TUnit.Core.Helpers.CastHelper.Cast<global::System.DateTime>(args[2]));
+    }
+    [global::System.Runtime.CompilerServices.ModuleInitializer]
+    internal static void Initialize()
+    {
+        global::TUnit.Core.SourceRegistrar.Register(typeof(global::TUnit.TestProject.Bugs._5118.AsyncClassMethodDataSourceTests), TUnit_TestProject_Bugs__5118_AsyncClassMethodDataSourceTests__TestSource.GetTests, TUnit_TestProject_Bugs__5118_AsyncClassMethodDataSourceTests__TestSource.EnumerateTestDescriptors);
+    }
+}

TUnit.Core.SourceGenerator/Generators/TestMetadataGenerator.cs

@@ -842,7 +842,16 @@ private static void GenerateMethodDataSourceAttribute(CodeWriter writer, Attribu
         {
             // MethodDataSource(string) overload
             methodName = attr.ConstructorArguments[0].Value?.ToString();
-            targetType = typeSymbol;
+
+            // Check for MethodDataSource<T> generic variant - extract T from type arguments
+            if (attr.AttributeClass is { IsGenericType: true })
+            {
+                targetType = attr.AttributeClass.TypeArguments[0];
+            }
+            else
+            {
+                targetType = typeSymbol;
+            }
         }
 
         if (string.IsNullOrEmpty(methodName))
@@ -894,7 +903,9 @@ private static void GenerateMethodDataSourceAttribute(CodeWriter writer, Attribu
         }
         else
         {
-            // MethodDataSource(string) constructor
+            // MethodDataSource(string) constructor — ClassProvidingDataSource is intentionally null here
+            // because the Factory delegate (set below) already encodes the correct target type directly.
+            // The runtime attribute only needs ClassProvidingDataSource for reflection-based lookup.
             writer.AppendLine($"new {attrTypeName}(\"{methodName}\")");
         }
         writer.AppendLine("{");

TUnit.Core/Attributes/TestData/MethodDataSourceAttribute.cs

@@ -228,7 +228,9 @@ public MethodDataSourceAttribute(
         }
 
         // Compute paramTypes once to avoid repeated LINQ allocations
-        var paramTypes = GetParameterTypes(dataGeneratorMetadata.TestInformation?.Parameters);
+        // Use MembersToGenerate which contains the correct parameters for this data generator type
+        // (constructor params for class-level, method params for method-level)
+        var paramTypes = GetMemberTypes(dataGeneratorMetadata.MembersToGenerate);
 
         // If it's IAsyncEnumerable, handle it specially
         if (IsAsyncEnumerable(methodResult.GetType()))
@@ -310,17 +312,23 @@ public MethodDataSourceAttribute(
         }
     }
 
-    private static Type[]? GetParameterTypes(ParameterMetadata[]? parameters)
+    private static Type[]? GetMemberTypes(IMemberMetadata[]? members)
     {
-        if (parameters == null || parameters.Length == 0)
+        if (members == null || members.Length == 0)
         {
             return null;
         }
 
-        var types = new Type[parameters.Length];
-        for (var i = 0; i < parameters.Length; i++)
+        var types = new Type[members.Length];
+        for (var i = 0; i < members.Length; i++)
         {
-            types[i] = parameters[i].Type;
+            types[i] = members[i] switch
+            {
+                ParameterMetadata param => param.Type,
+                PropertyMetadata prop => prop.Type,
+                _ => throw new InvalidOperationException(
+                    $"Unexpected member metadata type {members[i].GetType().Name} in GetMemberTypes")
+            };
         }
         return types;
     }

TUnit.TestProject/Bugs/5118/AsyncClassMethodDataSourceTests.cs

@@ -0,0 +1,29 @@
+using TUnit.TestProject.Attributes;
+
+namespace TUnit.TestProject.Bugs._5118;
+
+public class AsyncTestDataSources
+{
+    public static async IAsyncEnumerable<(int Id, string Name, DateTime CreatedAt)> GetAsyncTestData()
+    {
+        for (var i = 1; i <= 3; i++)
+        {
+            await Task.Delay(10).ConfigureAwait(false);
+
+            yield return (Id: i, Name: $"Item_{i}", CreatedAt: DateTime.UtcNow.AddDays(-i));
+        }
+    }
+}
+
+[EngineTest(ExpectedResult.Pass)]
+[MethodDataSource<AsyncTestDataSources>(nameof(AsyncTestDataSources.GetAsyncTestData))]
+public class AsyncClassMethodDataSourceTests(int Id, string Name, DateTime CreatedAt)
+{
+    [Test, Timeout(5000)]
+    public async Task TestWithAsyncComplexData(CancellationToken token)
+    {
+        await Assert.That(Id).IsGreaterThan(0);
+        await Assert.That(Name).StartsWith("Item_");
+        await Assert.That(CreatedAt).IsLessThan(DateTime.UtcNow);
+    }
+}