Sometimes, when I mock a method in Mockito, I used anyString instead of any and I get into a mess and my test fails. Why? given(mUserRepo.getUser(anyString(). any())).willReturn(new User()); And what will happen if mUserRepo.getUser(null); UserRepo is called with null? Well, the matcher doesn’t work and the test fails. anyString() does not work with null values. If you pass null to a mocked service then use any() as a matcher.
Probably, most of you already know this, but it is good to keep it in mind when you want to dynamically change the values returned by a mock you have.
Edit 23.04.2018 According to this issue, Mockito cannot capture var-args still. There is a very easy way to verify a method has been called with the right parameter in Mockito. All you need to do is use captors, to capture the actual argument. Here is how you can use them: ArgumentCaptor argument = ArgumentCaptor.forClass(RuleEntity.class); verify(mRulesRepository).createRule(argument.capture()); assertEquals(1,argument.getValue().getRules().get(0).getTriggers().size()) Simple it is, just a quick reminder for starters.