java - Does when() in Mockito verify invocation with strict parameter?

Question

I am curious if when(mock.method(SPECIFIC_PARAM)).thenReturn(RETURN_VAlUE); checks for invocation of method. Or should I do verify(mock).method(SPECIFIC_PARAM); to make sure the method has been invoked?

question from:https://stackoverflow.com/questions/66067360/does-when-in-mockito-verify-invocation-with-strict-parameter

Answer 1

If you use @RunWith(MockitoJUnitRunner.class) or @ExtendWith(MockitoExtension.class), you will get an UnnecessaryStubbingException after running a test if you provided a mock that is not used.

You can avoid this by setting @MockitoSettings(strictness = Strictness.LENIENT) if you want to.

But even with the UnnecessaryStubbingException, it's still better to do an actual verify inside your test for readability. Your 'verify' can also be stricter than your stub, e.g:

when(mock.method(anyCollection())).thenReturn(...)
...
mock.method(collection);
...
verify(mock).method(argThat(collection -> collection.size()==1));