I usually find a fundamental misunderstanding of mocking. Use of mocks isn't a problem. Poor use of mocks is a problem. Mocks aren't there so you can test. Mocks are there so you can test only what you want to test. They're there so you can isolate the thing being tested from the thing(s) not being tested.
So what do you want to test?
That changes with the context. Unit tests? I want to test a "unit" of code. What is "unit"? That varies. Integration tests? I want to test the integration of two or more things. System test? I want to test the system! End-to-end, I might be testing more than the system.
Back to the important point. It doesn't matter what size test I have, I still need to isolate the thing I'm testing. Mocks (or stubs or dummies or fakes or etc.) are one way to do it.
The key is: any time a mock isn't used to isolate the subject under test it's being used wrong. Every article I've ever seen about mocks gets this wrong. They always show an example of a mock completely isolating away the subject under test (the "doesn't test anything" ClientTests shown above), isolating the wrong things, or isolating in the wrong way.
Check out Gerard Meszaros' xUnit Test Patterns book. It will change your life.
I usually find a fundamental misunderstanding of mocking. Use of mocks isn't a problem. Poor use of mocks is a problem. Mocks aren't there so you can test. Mocks are there so you can test only what you want to test. They're there so you can isolate the thing being tested from the thing(s) not being tested.
So what do you want to test?
That changes with the context. Unit tests? I want to test a "unit" of code. What is "unit"? That varies. Integration tests? I want to test the integration of two or more things. System test? I want to test the system! End-to-end, I might be testing more than the system.
Back to the important point. It doesn't matter what size test I have, I still need to isolate the thing I'm testing. Mocks (or stubs or dummies or fakes or etc.) are one way to do it.
The key is: any time a mock isn't used to isolate the subject under test it's being used wrong. Every article I've ever seen about mocks gets this wrong. They always show an example of a mock completely isolating away the subject under test (the "doesn't test anything" ClientTests shown above), isolating the wrong things, or isolating in the wrong way.
Check out Gerard Meszaros' xUnit Test Patterns book. It will change your life.
Yup, totally agree. Mocking is a great tool. It's misused in one way or another in almost every codebase I've ever worked with.