When using fake timers, waitFor still uses a setTimeout with real timers

[pierrezimmermannbam]

Describe the bug

waitFor timeout is using real time when using fake timers, so the fake timers are not necessarily advanced of the timeout. This bug is visible only if the time to perform the check is greater than the interval but it can happen for queries on large components (I met this bug when working on a real codebase).

The following test will fail because the time needed to perform the check is greater than 5ms

test.each([false, true])(
  'it should not depend on real time when using fake timers (legacyFakeTimers = %s)',
  async () => {
    jest.useFakeTimers({ legacyFakeTimers: false });

    const mockErrorFn = jest.fn(() => {
      fibonaci(30);
      throw new Error('test');
    });

    try {
      await waitFor(() => mockErrorFn(), {
        timeout: 200,
        interval: 5,
      });
    } catch (error) {
      // suppress
    }

    expect(mockErrorFn).toHaveBeenCalledTimes(41);
  }
);

Expected behavior

I think this is confusing, as we can't use waitFor in a stable way to advance fake timers and I'd expect than when waitFor fails, the timers have been advanced by its timeout.
However I'm not sure if there is a reason why it was implemented like this, @mdjastrzebski any ideas ?

Steps to Reproduce

The test above fails on the RNTL repo

Screenshots

Versions

[AugustinLF]

Oh great catch! It should be the cause of some really weird bugs I've had in my code, when different type of fake timers would break a RNTL (without any clear reason), while working on RNTL.