public void GenericMethodWithOutDecimalParameter() { IMyInterface mock = MockRepository.Mock <IMyInterface>(); decimal expectedOutParameter = 1.234M; //decimal emptyOutParameter; mock.Expect(x => x.GenericMethod(out Arg <decimal> .Out(expectedOutParameter).Dummy)); decimal outParameter; mock.GenericMethod(out outParameter); Assert.Equal(expectedOutParameter, outParameter); }