# Default Mock Expectations

Often in unit testing, we end up with sets of tests which use the same object dependency over and over again. Rather than mocking this class/object within every single unit test (requiring a mountain of duplicate code), we can instead define reusable default mocks within the test case’s `setup()` method. This even works where unit tests use varying expectations on the same or similar mock object.

How this works, is that you can define mocks with default expectations. Then, in a later unit test, you can add or fine-tune expectations for that specific test. Any expectation can be set as a default using the `byDefault()` declaration.