Interface Default methods are ignored

[hahn-kev]

I'm not sure if this would be considered a bug, but I'd think it would work the same as mocking an abstract class.

Example

interface ITest
{
    string CallMe();

    string CallMeDefault()
    {
        return CallMe();
    }
}

[Fact]
public void DefaultFails()
{
    var mock = new Mock<ITest>(MockBehavior.Loose);
    mock.Setup(t => t.CallMe()).Returns("hello");
    Assert.NotNull(mock.Object.CallMeDefault());
}

My interface has the method CallMeDefault which has an implementation, however when I mock that interface it gets overridden and calling that method returns null instead of what CallMe returns as I'd expect. I think ideally this would follow the CallBase setting, however it doesn't seem like it does.

[stakx]

Before Moq can support default interface methods, DynamicProxy must add support for them; see castleproject/Core#447.

[stakx]

@hahn-kev: OK, I think this can be made to work. You'll have to configure CallBase behavior for your CallMeDefault interface method, either at the setup level:

 var mock = new Mock<ITest>(MockBehavior.Loose);
 mock.Setup(t => t.CallMe()).Returns("hello");
+mock.Setup(t => t.CallMeDefault()).CallBase();
 Assert.NotNull(mock.Object.CallMeDefault());

or at the mock level (whatever is a better fit for your tests):

-var mock = new Mock<ITest>(MockBehavior.Loose);
+var mock = new Mock<ITest>(MockBehavior.Loose) { CallBase = true };
 mock.Setup(t => t.CallMe()).Returns("hello");
 Assert.NotNull(mock.Object.CallMeDefault());

In terms of default interface implementations, .CallBase() shall call the most specific override.