Write a recommendation for asserting multiple things on a signal

[DominicOram]

As a developer I may want to check multiple things on a mocked signal. Currently we have assert_mock_put_called_with but what if I want to assert many calls on the mock? We can currently do this with something like:

def call_another_mock(call_log: MagicMock):
    def _call_another_mock(value, **kwargs):
        call_log(value, **kwargs)

    return _call_another_mock

def test():
    call_log = MagicMock()
    callback_on_mock_put(my_device, call_another_mock(call_log))
    call_log.assert_has_calls(_call_list((5.3375, -3.55, 2.43, 48.974, 15.8)))

This is fine except:

• There is already a mock internally that we could use
• Adds downstream boilerplate

Some other ways we could do it are:

• Allow access to the mock:

def get_mock(signal: Signal) -> Mock:
    backend = _get_mock_signal_backend(signal)
    return backend.put_mock

• Add a def assert_mock_has_calls(signal: Signal, calls) - I'm not a big fan of this as it seems a slippery slope to re-implementing mock

Acceptance Criteria

• We decide on the preferred solution
• If it needs implementing implement it
• Document what the preferred solution is at https://blueskyproject.io/ophyd-async/main/how-to/write-tests-for-devices.html

[callumforrester]

Allowing access to the mock seems like a good idea to me.

[coretl]

Two opposing suggestions:

1. Remove assert_mock_put_called_with, and replace with get_mock_put(signal). The only downside is the usual problem with mock, if I type mock.assret_has_calls(calls) (as I have sometimes done) then the test passes as the mock just gives me back another mock and calls it with calls. I don't know if there is a way to get it not to do this?
2. Add assert_mock_put_has_calls and assert_mock_put_not_called and all the other ones

I think I prefer 1., but I would love it if there was a way to catch the typo issue...

[DominicOram]

Yh, 2 is a slippery slope. I'm happy to go 1. I think you can avoid the typo problem by using spec, e.g.

class MyClass():
    def blah(self):
         ...

Mock(spec=MyClass) # This can only be called with blah() or the methods inherent to Mock

I'm happy to look at this as part of this issue?

[coretl]

I'm happy to look at this as part of this issue?

Yes please!