thomhurst · thomhurst · Dec 22, 2025 · Dec 22, 2025 · Dec 22, 2025
diff --git a/TUnit.Core.SourceGenerator.Tests/MatrixTests.Test.verified.txt b/TUnit.Core.SourceGenerator.Tests/MatrixTests.Test.verified.txt
@@ -1365,3 +1365,117 @@ internal static class TUnit_TestProject_MatrixTests_Exclusion__int_int_ModuleIni
         global::TUnit.Core.SourceRegistrar.Register(typeof(global::TUnit.TestProject.MatrixTests), new TUnit_TestProject_MatrixTests_Exclusion__int_int_TestSource());
     }
 }
+
+
+// ===== FILE SEPARATOR =====
+
+// <auto-generated/>
+#pragma warning disable
+
+#nullable enable
+namespace TUnit.Generated;
+internal sealed class TUnit_TestProject_MatrixTests_MatrixMethod_WithEnumParameter_UsesOnlyMethodValues__bool_CountToTenEnum_TestSource : global::TUnit.Core.Interfaces.SourceGenerator.ITestSource
+{
+    public async global::System.Collections.Generic.IAsyncEnumerable<global::TUnit.Core.TestMetadata> GetTestsAsync(string testSessionId, [global::System.Runtime.CompilerServices.EnumeratorCancellation] global::System.Threading.CancellationToken cancellationToken = default)
+    {
+        var metadata = new global::TUnit.Core.TestMetadata<global::TUnit.TestProject.MatrixTests>
+        {
+            TestName = "MatrixMethod_WithEnumParameter_UsesOnlyMethodValues",
+            TestClassType = typeof(global::TUnit.TestProject.MatrixTests),
+            TestMethodName = "MatrixMethod_WithEnumParameter_UsesOnlyMethodValues",
+            Dependencies = global::System.Array.Empty<global::TUnit.Core.TestDependency>(),
+            AttributeFactory = static () =>
+            [
+                new global::TUnit.Core.TestAttribute(),
+                new global::TUnit.TestProject.Attributes.EngineTest(global::TUnit.TestProject.Attributes.ExpectedResult.Pass)
+            ],
+            DataSources = new global::TUnit.Core.IDataSourceAttribute[]
+            {
+                new global::TUnit.Core.MatrixDataSourceAttribute(),
+            },
+            ClassDataSources = global::System.Array.Empty<global::TUnit.Core.IDataSourceAttribute>(),
+            PropertyDataSources = global::System.Array.Empty<global::TUnit.Core.PropertyDataSource>(),
+            PropertyInjections = global::System.Array.Empty<global::TUnit.Core.PropertyInjectionData>(),
+            InheritanceDepth = 0,
+            FilePath = @"",
+            LineNumber = 197,
+            MethodMetadata = new global::TUnit.Core.MethodMetadata
+            {
+                Type = typeof(global::TUnit.TestProject.MatrixTests),
+                TypeInfo = new global::TUnit.Core.ConcreteType(typeof(global::TUnit.TestProject.MatrixTests)),
+                Name = "MatrixMethod_WithEnumParameter_UsesOnlyMethodValues",
+                GenericTypeCount = 0,
+                ReturnType = typeof(global::System.Threading.Tasks.Task),
+                ReturnTypeInfo = new global::TUnit.Core.ConcreteType(typeof(global::System.Threading.Tasks.Task)),
+                Parameters = new global::TUnit.Core.ParameterMetadata[]
+                {
+                    new global::TUnit.Core.ParameterMetadata(typeof(bool))
+                    {
+                        Name = "flag",
+                        TypeInfo = new global::TUnit.Core.ConcreteType(typeof(bool)),
+                        IsNullable = false,
+                        ReflectionInfo = typeof(global::TUnit.TestProject.MatrixTests).GetMethod("MatrixMethod_WithEnumParameter_UsesOnlyMethodValues", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] { typeof(bool), typeof(global::TUnit.TestProject.MatrixTests.CountToTenEnum) }, null)!.GetParameters()[0]
+                    },
+                    new global::TUnit.Core.ParameterMetadata(typeof(global::TUnit.TestProject.MatrixTests.CountToTenEnum))
+                    {
+                        Name = "enum",
+                        TypeInfo = new global::TUnit.Core.ConcreteType(typeof(global::TUnit.TestProject.MatrixTests.CountToTenEnum)),
+                        IsNullable = false,
+                        ReflectionInfo = typeof(global::TUnit.TestProject.MatrixTests).GetMethod("MatrixMethod_WithEnumParameter_UsesOnlyMethodValues", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] { typeof(bool), typeof(global::TUnit.TestProject.MatrixTests.CountToTenEnum) }, null)!.GetParameters()[1]
+                    }
+                },
+                Class = global::TUnit.Core.ClassMetadata.GetOrAdd("TestsBase`1:global::TUnit.TestProject.MatrixTests", static () => 
+                {
+                    var classMetadata = new global::TUnit.Core.ClassMetadata
+                    {
+                        Type = typeof(global::TUnit.TestProject.MatrixTests),
+                        TypeInfo = new global::TUnit.Core.ConcreteType(typeof(global::TUnit.TestProject.MatrixTests)),
+                        Name = "MatrixTests",
+                        Namespace = "TUnit.TestProject",
+                        Assembly = global::TUnit.Core.AssemblyMetadata.GetOrAdd("TestsBase`1", static () => new global::TUnit.Core.AssemblyMetadata { Name = "TestsBase`1" }),
+                        Parameters = global::System.Array.Empty<global::TUnit.Core.ParameterMetadata>(),
+                        Properties = global::System.Array.Empty<global::TUnit.Core.PropertyMetadata>(),
+                        Parent = null
+                    };
+                    foreach (var prop in classMetadata.Properties)
+                    {
+                        prop.ClassMetadata = classMetadata;
+                        prop.ContainingTypeMetadata = classMetadata;
+                    }
+                    return classMetadata;
+                })
+            },
+            InstanceFactory = (typeArgs, args) => new global::TUnit.TestProject.MatrixTests(),
+            InvokeTypedTest = static (instance, args, cancellationToken) =>
+            {
+                try
+                {
+                    switch (args.Length)
+                    {
+                        case 2:
+                            {
+                                return new global::System.Threading.Tasks.ValueTask(instance.MatrixMethod_WithEnumParameter_UsesOnlyMethodValues(TUnit.Core.Helpers.CastHelper.Cast<bool>(args[0]), TUnit.Core.Helpers.CastHelper.Cast<global::TUnit.TestProject.MatrixTests.CountToTenEnum>(args[1])));
+                            }
+                        default:
+                            throw new global::System.ArgumentException($"Expected exactly 2 arguments, but got {args.Length}");
+                    }
+                }
+                catch (global::System.Exception ex)
+                {
+                    return new global::System.Threading.Tasks.ValueTask(global::System.Threading.Tasks.Task.FromException(ex));
+                }
+            },
+        };
+        metadata.UseRuntimeDataGeneration(testSessionId);
+        yield return metadata;
+        yield break;
+    }
+}
+internal static class TUnit_TestProject_MatrixTests_MatrixMethod_WithEnumParameter_UsesOnlyMethodValues__bool_CountToTenEnum_ModuleInitializer
+{
+    [global::System.Runtime.CompilerServices.ModuleInitializer]
+    public static void Initialize()
+    {
+        global::TUnit.Core.SourceRegistrar.Register(typeof(global::TUnit.TestProject.MatrixTests), new TUnit_TestProject_MatrixTests_MatrixMethod_WithEnumParameter_UsesOnlyMethodValues__bool_CountToTenEnum_TestSource());
+    }
+}
diff --git a/TUnit.Core.SourceGenerator/CodeGenerationHelpers.cs b/TUnit.Core.SourceGenerator/CodeGenerationHelpers.cs
@@ -49,14 +49,16 @@ public static string GenerateParameterMetadataArray(IMethodSymbol method)
                     }
 
                     // Generate cached data source attributes for AOT compatibility
+                    // Include both IDataSourceAttribute and IDataSourceMemberAttribute implementations
                     var dataSourceAttributes = param.GetAttributes()
                         .Where(attr => attr.AttributeClass != null &&
-                               attr.AttributeClass.AllInterfaces.Any(i => i.Name == "IDataSourceAttribute"))
+                               attr.AttributeClass.AllInterfaces.Any(i =>
+                                   i.Name == "IDataSourceAttribute" || i.Name == "IDataSourceMemberAttribute"))
                         .ToArray();
 
                     if (dataSourceAttributes.Length > 0)
                     {
-                        writer.AppendLine($"CachedDataSourceAttributes = new global::TUnit.Core.IDataSourceAttribute[]");
+                        writer.AppendLine($"CachedDataSourceAttributes = new global::System.Attribute[]");
                         writer.AppendLine("{");
                         writer.SetIndentLevel(3);
                         foreach (var attr in dataSourceAttributes)

diff --git a/TUnit.Core/Attributes/TestData/CombinedDataSourcesAttribute.cs b/TUnit.Core/Attributes/TestData/CombinedDataSourcesAttribute.cs
@@ -126,7 +126,9 @@ public sealed class CombinedDataSourcesAttribute : AsyncUntypedDataSourceGenerat
         if (parameterMetadata.CachedDataSourceAttributes != null)
         {
             // Source-generated mode: use cached attributes (no reflection!)
-            dataSourceAttributes = parameterMetadata.CachedDataSourceAttributes;
+            dataSourceAttributes = parameterMetadata.CachedDataSourceAttributes
+                .OfType<IDataSourceAttribute>()
+                .ToArray();
         }
         else
         {

diff --git a/TUnit.Core/Attributes/TestData/IDataSourceMemberAttribute.cs b/TUnit.Core/Attributes/TestData/IDataSourceMemberAttribute.cs
@@ -0,0 +1,9 @@
+namespace TUnit.Core;
+
+/// <summary>
+/// Marker interface for attributes that provide data values for individual parameters
+/// within a data source context (e.g., matrix testing).
+/// Attributes implementing this interface will be cached by the source generator
+/// for AOT-compatible runtime access.
+/// </summary>
+public interface IDataSourceMemberAttribute;
diff --git a/TUnit.Core/Attributes/TestData/MatrixSourceAttribute.cs b/TUnit.Core/Attributes/TestData/MatrixSourceAttribute.cs
@@ -42,7 +42,7 @@ namespace TUnit.Core;
 /// </remarks>
 /// <param name="objects">The values to be used for this parameter in the test matrix.</param>
 [AttributeUsage(AttributeTargets.Parameter)]
-public class MatrixAttribute(params object?[]? objects) : TUnitAttribute
+public class MatrixAttribute(params object?[]? objects) : TUnitAttribute, IDataSourceMemberAttribute
 {
     protected MatrixAttribute() : this(null)
     {

diff --git a/TUnit.Core/Models/TestModels/ParameterMetadata.cs b/TUnit.Core/Models/TestModels/ParameterMetadata.cs
@@ -56,9 +56,10 @@ public record ParameterMetadata([DynamicallyAccessedMembers(DynamicallyAccessedM
     /// Cached data source attributes to avoid reflection call.
     /// Set by source generator for AOT compatibility.
     /// When null, falls back to using ReflectionInfo.GetCustomAttributes().
+    /// Includes attributes implementing IDataSourceAttribute or IDataSourceMemberAttribute.
     /// </summary>
     [EditorBrowsable(EditorBrowsableState.Never)]
-    public IDataSourceAttribute[]? CachedDataSourceAttributes { get; internal init; }
+    public Attribute[]? CachedDataSourceAttributes { get; internal init; }
 
     /// <summary>
     /// Position of this parameter in the method/constructor signature.

diff --git a/TUnit.Engine.Tests/MatrixTests.cs b/TUnit.Engine.Tests/MatrixTests.cs
@@ -8,7 +8,7 @@ public class MatrixTests(TestMode testMode) : InvokableTestBase(testMode)
     [Test]
     public async Task Test()
     {
-        var expectedCount = IsNetFramework ? 133 : 271;
+        var expectedCount = IsNetFramework ? 137 : 275;
 
         await RunTestsWithFilter(
             "/*/*/MatrixTests/*",

diff --git a/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.DotNet10_0.verified.txt b/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.DotNet10_0.verified.txt
@@ -864,6 +864,7 @@ namespace
         bool SkipIfEmpty { get; set; }
         .<<.<object?[]?>>> GetDataRowsAsync(.DataGeneratorMetadata dataGeneratorMetadata);
     }
+    public interface IDataSourceMemberAttribute { }
     public interface IDynamicTestCreatorLocation
     {
         string? CreatorFilePath { get; set; }
@@ -909,7 +910,7 @@ namespace
         public InvalidTestMetadataException(string message, .TestMetadata metadata,  innerException) { }
     }
     [(.Parameter)]
-    public class MatrixAttribute : .TUnitAttribute
+    public class MatrixAttribute : .TUnitAttribute, .IDataSourceMemberAttribute
     {
         protected MatrixAttribute() { }
         public MatrixAttribute(params object?[]? objects) { }
@@ -1053,7 +1054,7 @@ namespace
     public class ParameterMetadata : <.ParameterMetadata>, .IMemberMetadata
     {
         public ParameterMetadata([.(..None | ..PublicParameterlessConstructor | ..PublicConstructors | ..NonPublicConstructors | ..PublicProperties)]  Type) { }
-        public .IDataSourceAttribute[]? CachedDataSourceAttributes { get; }
+        public []? CachedDataSourceAttributes { get; }
         public object? CachedDefaultValue { get; }
         public bool? CachedIsOptional { get; }
         public bool? CachedIsParams { get; }

diff --git a/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.DotNet8_0.verified.txt b/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.DotNet8_0.verified.txt
@@ -864,6 +864,7 @@ namespace
         bool SkipIfEmpty { get; set; }
         .<<.<object?[]?>>> GetDataRowsAsync(.DataGeneratorMetadata dataGeneratorMetadata);
     }
+    public interface IDataSourceMemberAttribute { }
     public interface IDynamicTestCreatorLocation
     {
         string? CreatorFilePath { get; set; }
@@ -909,7 +910,7 @@ namespace
         public InvalidTestMetadataException(string message, .TestMetadata metadata,  innerException) { }
     }
     [(.Parameter)]
-    public class MatrixAttribute : .TUnitAttribute
+    public class MatrixAttribute : .TUnitAttribute, .IDataSourceMemberAttribute
     {
         protected MatrixAttribute() { }
         public MatrixAttribute(params object?[]? objects) { }
@@ -1053,7 +1054,7 @@ namespace
     public class ParameterMetadata : <.ParameterMetadata>, .IMemberMetadata
     {
         public ParameterMetadata([.(..None | ..PublicParameterlessConstructor | ..PublicConstructors | ..NonPublicConstructors | ..PublicProperties)]  Type) { }
-        public .IDataSourceAttribute[]? CachedDataSourceAttributes { get; }
+        public []? CachedDataSourceAttributes { get; }
         public object? CachedDefaultValue { get; }
         public bool? CachedIsOptional { get; }
         public bool? CachedIsParams { get; }

diff --git a/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.DotNet9_0.verified.txt b/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.DotNet9_0.verified.txt
@@ -864,6 +864,7 @@ namespace
         bool SkipIfEmpty { get; set; }
         .<<.<object?[]?>>> GetDataRowsAsync(.DataGeneratorMetadata dataGeneratorMetadata);
     }
+    public interface IDataSourceMemberAttribute { }
     public interface IDynamicTestCreatorLocation
     {
         string? CreatorFilePath { get; set; }
@@ -909,7 +910,7 @@ namespace
         public InvalidTestMetadataException(string message, .TestMetadata metadata,  innerException) { }
     }
     [(.Parameter)]
-    public class MatrixAttribute : .TUnitAttribute
+    public class MatrixAttribute : .TUnitAttribute, .IDataSourceMemberAttribute
     {
         protected MatrixAttribute() { }
         public MatrixAttribute(params object?[]? objects) { }
@@ -1053,7 +1054,7 @@ namespace
     public class ParameterMetadata : <.ParameterMetadata>, .IMemberMetadata
     {
         public ParameterMetadata([.(..None | ..PublicParameterlessConstructor | ..PublicConstructors | ..NonPublicConstructors | ..PublicProperties)]  Type) { }
-        public .IDataSourceAttribute[]? CachedDataSourceAttributes { get; }
+        public []? CachedDataSourceAttributes { get; }
         public object? CachedDefaultValue { get; }
         public bool? CachedIsOptional { get; }
         public bool? CachedIsParams { get; }

diff --git a/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.Net4_7.verified.txt b/TUnit.PublicAPI/Tests.Core_Library_Has_No_API_Changes.Net4_7.verified.txt
@@ -841,6 +841,7 @@ namespace
         bool SkipIfEmpty { get; set; }
         .<<.<object?[]?>>> GetDataRowsAsync(.DataGeneratorMetadata dataGeneratorMetadata);
     }
+    public interface IDataSourceMemberAttribute { }
     public interface IDynamicTestCreatorLocation
     {
         string? CreatorFilePath { get; set; }
@@ -886,7 +887,7 @@ namespace
         public InvalidTestMetadataException(string message, .TestMetadata metadata,  innerException) { }
     }
     [(.Parameter)]
-    public class MatrixAttribute : .TUnitAttribute
+    public class MatrixAttribute : .TUnitAttribute, .IDataSourceMemberAttribute
     {
         protected MatrixAttribute() { }
         public MatrixAttribute(params object?[]? objects) { }
@@ -1016,7 +1017,7 @@ namespace
     public class ParameterMetadata : <.ParameterMetadata>, .IMemberMetadata
     {
         public ParameterMetadata( Type) { }
-        public .IDataSourceAttribute[]? CachedDataSourceAttributes { get; }
+        public []? CachedDataSourceAttributes { get; }
         public object? CachedDefaultValue { get; }
         public bool? CachedIsOptional { get; }
         public bool? CachedIsParams { get; }

diff --git a/TUnit.TestProject/MatrixTests.cs b/TUnit.TestProject/MatrixTests.cs
@@ -192,4 +192,22 @@ public static object ObjectMethod()
     {
         return 1;
     }
+
+    // Test for GitHub Discussion #4145: MatrixMethod with enum parameter
+    [Test]
+    [MatrixDataSource]
+    public async Task MatrixMethod_WithEnumParameter_UsesOnlyMethodValues(
+        [Matrix(true, false)] bool flag,
+        [MatrixMethod<MatrixTests>(nameof(GetSpecificEnumValues))] CountToTenEnum @enum)
+    {
+        // This test verifies that MatrixMethod returns only the specific enum values
+        // and doesn't auto-generate all enum values (should only be One or Five)
+        await Assert.That(@enum == CountToTenEnum.One || @enum == CountToTenEnum.Five).IsTrue();
+    }
+
+    public static IEnumerable<CountToTenEnum> GetSpecificEnumValues()
+    {
+        yield return CountToTenEnum.One;
+        yield return CountToTenEnum.Five;
+    }
 }