async callable not awaited in side_effect for AsyncMock

Bug report

Bug description:

In the AsyncMockMixin._execute_mock_call, the following test is done:

        if effect is not None:
            if _is_exception(effect):
                raise effect
            elif not _callable(effect):
                try:
                    result = next(effect)
                except StopIteration:
                    # It is impossible to propagate a StopIteration
                    # through coroutines because of PEP 479
                    raise StopAsyncIteration
                if _is_exception(result):
                    raise result
            elif iscoroutinefunction(effect):
                result = await effect(*args, **kwargs)
            else:
                result = effect(*args, **kwargs)

However elif iscoroutinefunction(effect) will return False for an awaitable that was defined this way:

    class AsyncCallable:
        async def __call__(self, *args, **kwargs):
            # await stuff
            pass

Note that __call__ is awaitable here but not detected as such.

iscoroutinefunction(effect.__call__) would return True in such a case however, so the fix might be as simple as:

            elif iscoroutinefunction(effect) or iscoroutinefunction(getattr(effect, '__call__', None)):

In the meantime, the workaround is to add markcoroutinefunction(self) to the class.

    class AsyncCallable:
        def __init__(self, *args, **kwargs):
            # init code
            markcoroutinefunction(self)  # workaround for iscoroutinefunction check in side_effect to return True

        ...

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-156465

Start in Lib/unittest/mock.py at AsyncMockMixin._execute_mock_call and review the linked PR gh-156465. Confirm the behavior for an object whose async call method is used as AsyncMock.side_effect, then add or update regression coverage so that callable is awaited correctly.