New rule to disallow using mock API in end-to-end test files

[mrazauskas]

What about adding a rule which would disallows using mock APIs? I though it could be activated for a directory where end-to-end tests live and could ensure that test fixtures are used instead of mocks.

Usually I prefer to leave mocks and spies for unit tests and to avoid them in end-to-end tests. Just wanted to check what people smarter than me think? (;

[SimenB]

I think a rule disallowing using module mocking makes sense. Would you also want fake time, jest.fn etc to be disallowed, or only jest.mock, jest.doMock etc.?

[mrazauskas]

Let’s think.

jest.fn, jest.mock, jest.spyOn, jest.doMock, jest.setMock – are good candidates be banned.

Disallowing fake time sounds tricky. I think there should be an option allowing to ban everything except faking time. Testing server side APIs or web apps might depend on fake time in the end-to-end tests. In general it sounds good to have this configuration option.

[SimenB]

Sounds like you want to ban usage of jest.* in general. What APIs would you want? Only thing I can think of that's not mocking modules or mocking time is jest.retryTimes - at which point that one usage can probably be enabled via an eslint comment

[mrazauskas]

Also jest.setTimeout should be there. Probably.

[G-Rath]

It sounds like we should do a no-restricted-jest-methods to complement no-restricted-matchers, and then you'd want to use both together for your specific use-case (as you'd want to disable use of matchers like toHaveBeenCalled)

[mrazauskas]

Yep. That sounds right.

Actually my first idea was to suggest adding no-restricted-jest-methods, but it felt too abstract. The purpose did not look clear. Now after comments from Simen and you, I see that the first idea was right. The rest was pure overthinking ;D