Description

When a mock is generated, the constraints from a generic interface method are copied to the explicit interface implementation which causes the compiler error CS0460: Constraints for override and explicit interface implementation methods are inherited from the base method, so they cannot be specified directly, except for either a 'class', or a 'struct' constraint., when there are constraints other than class and struct.

Expected Behavior

The source generator does not copy constraints from the interface. If a generic type parameter is unconstrained, the default constraint should still be used (see #5362)

Actual Behavior

The constraints are copied to the explicit interface implementation causing CS0460

Steps to Reproduce

using TUnit.Mocks.Generated.Sandbox;

namespace Sandbox;

public interface IFoo {
    T Get<T>(string key) where T : notnull; // or any other constraint like `unmanaged`, `new()`, `<base type>`...
}

public class TestClass {
    [Test]
    public async Task SomeTest() {
        IFooMock mockInt = IFoo.Mock(); // CS0460
    }
}

TUnit Version

1.28.0-beta

.NET Version

.NET 10.0

Operating System

Windows

IDE / Test Runner

JetBrains Rider

Error Output / Stack Trace

Restore complete (0.8s)
  Sandbox net10.0 failed with 1 error(s) (0.6s)
    /mnt/x/Sandbox/Sandbox/obj/Debug/net10.0/TUnit.Mocks.SourceGenerator/TUnit.Mocks.SourceGenerator.MockGenerator/Sandbox_IFoo_Mock.g.cs(12,61): error CS0460: Constraints for override and explicit interface implementation methods are inherited from the base method, so they cannot be specified directly, except for either a 'class', or a 'struct' constraint.

Build failed with 1 error(s) in 1.8s

Additional Context

No response

IDE-Specific Issue?

• I've confirmed this issue occurs when running via dotnet test or dotnet run, not just in my IDE