Question

I have started using moq for mocking. Can someone explain me the concept of strict and non-strict mocks? How can they can be used in moq?

edit:
in which scenario do we use which type of mock?

Answer 1

I’m not sure about moq specifically, but here’s how strict mocks work in Rhino. I declare that I expect a call to foo.Bar on my object foo:

foo.Expect(f => f.Bar()).Returns(5);

If the calling code does

foo.Bar();

then I’m fine because the expectations are exactly met.

However, if the calling code is:

foo.Quux(12);
foo.Bar();

then my expectation failed because I did not explicitly expect a call to foo.Quux.

To summarize, a strict mock will fail immediately if anything differs from the expectations. On the other hand, a non-strict mock (or a stub) will gladly “ignore” the call to foo.Quux and it should return a default(T) for the return type T of foo.Quux.

The creator of Rhino recommends that you avoid strict mocks (and prefer stubs) because you generally don’t want your test to fail when receiving an unexpected call as above. It makes refactoring your code much more difficult when you have to fix dozens of test that relied on the exact original behavior.