> if there is any sort of integration (two things interacting: your test setup can tell you that's happening), it's an integration test. Two things of what? Th

> if there is any sort of integration (two things interacting: your test setup can tell you that's happening), it's an integration test. Two things of what? There are people that claim that as soon as there are more than one method involved, it's an integration test, and more common, that as soon as there are more than one class involved, it is. This lead to absurd mocking of utility classes to make sure that only one thing is tested at the time. And then, of course, the tests become very fragile. And while there are situations when it is useful to only test one specific thing, what we really care about is the behaviour of whole system of many parts. We mock (fake or stub) to make the tests faster, repeatable and reliable. That is, what we don't want in our tests are slow calls, over slow networks or lengthy calculations. We want the calls to be repeatable, so we don't want to call, say, a database where the state changes between test runs. And we don't want to make calls to unreliable services; unreliable because they are under development or because they are over an unreliable network.