Using Rhino Mocks to mock an out parameter, which is created within the method I am testing

Question

Trying to mock the following method:

bool IsLoginValid(LoginViewModel viewModel, out User user); 

Tried this initially:

dependency<ILoginService>() .Stub(serv =>         serv.IsLoginValid(             Arg<LoginViewModel>.Is.Equal(a_login_viewmodel),             out Arg<User>.Is.Anything) .Return(false); 

But, that fails, as it is an out parameter. Did a bit of searching around and altered my code like such:

dependency<ILoginService>() .Stub(serv =>          serv.IsLoginValid(             Arg<LoginViewModel>.Is.Equal(a_login_viewmodel),              out Arg<User>.Out(new User()).Dummy)) .Return(false); 

That also fails. I need 'new User()' to be sort of an 'Anything' argument. As I think that is expecting a specific instance.

Any idea how to get around this? Thanks guys.

Answer 1

Try the "OutRef" option. It accepts a params object[] that defines the result for each out parameter. Since you've only got one, you only need one result. Here's a quick mock-up of what I tried that should work in your situation:

var foo = MockRepository.GenerateStub<IFoo>(); var viewModel = new LoginViewModel(); User temp; foo.Stub(f => f.IsLoginValid(viewModel, out temp)).OutRef(new User()).Return(false);  User outparam; Assert.IsFalse(foo.IsLoginValid(viewModel, out outparam));