Rails Fixtures vs. Mocks

Question

Hi there,

I'm developing a Rails app, and I was just talking with my colleague that we have a mix of fixtures and mocks in our tests, which we're doing using cucumber and Rspec. The question would be: when should each one be used?

Answer 1

I would use a mock object when using the real object is impracticable/not necessary. Lets say for example you need to call some remote API such as an address finder via zip code. You would probably want to mock the object so the calls on it aren't actually made each time you run your tests. There are other reasons too such as improving speed, asking for data that changes where you need an exact response or perhaps it doesn't exist yet. It allows you to test things in isolation as you can determine that when you call these methods on this mock object you will get this back and you don't actually need to run the code as for this test it's not important.

If you use fixtures you will have a real object and the methods etc will be called and their code run, unless of course you stub the methods out, which is something for another question.

Hope that helps a little. There is a good peepcode (http://peepcode.com/products/rspec-mocks-and-models) on mocking and stubbing, maybe check it out.