Testing: Mock object will always return True!

[wxtim]

Investigate replacing tests/unit/test_indep_task_queues.py with an integration test.

Description

The code at

cylc-flow/tests/unit/test_indep_task_queues.py

Line 96 in 36a6ce9

assert r.state.reset.called_with(TASK_STATUS_PREPARING)

does not work as desired: One may add a line such as

        assert r.state.garbage_method.called_with(TASK_STATUS_PREPARING)

Which will also pass!

As explained in python/cpython#100690 this is because up to Python 3.11

(Pdb) type(r.state.reset.called_with)
<class 'unittest.mock.Mock'>

which will return true, and not as the reader would expect, test the truth of that method having been called.

At Python 3.12 additional checks have been added, preventing this issue, but breaking the tests.

Investigate

Check whether the method under test should be called. I don't think that the state of the task should change - it should be waiting before and after so I suspect that this test shouldn't pass, and just needs correcting. We might want to test the task proxy's is_queued flag though.

It might be more sensible to run this as an integration test rather than a unit test.