event_loop_policy for single test

[Dreamsorcerer]

It would be good if there was an easy way to change the event_loop_policy for a single test. I can't see any way to do this currently from the documentation (other than moving a single test to it's own module).

In aiohttp, we currently have these fixtures in conftest.py, which I'm looking to remove:

@pytest.fixture
def selector_loop() -> Iterator[asyncio.AbstractEventLoop]:
    policy = asyncio.WindowsSelectorEventLoopPolicy()  # type: ignore[attr-defined]
    asyncio.set_event_loop_policy(policy)

    with loop_context(policy.new_event_loop) as:
        asyncio.set_event_loop(_loop)
        yield _loop


@pytest.fixture
def uvloop_loop() -> Iterator[asyncio.AbstractEventLoop]:
    policy = uvloop.EventLoopPolicy()
    asyncio.set_event_loop_policy(policy)

    with loop_context(policy.new_event_loop) as:
        asyncio.set_event_loop(_loop)
        yield _loop

[seifertm]

That makes sense. The event loop policy support is not in a good state, unfortunately. I think this is closely related to #796.

[seifertm]

I'm also linking #1032 which argues that this kind of customization should be possible through the async marker.
For example: @pytest.mark.asyncio(policy=…).

It's also worth mentioning that upstream is deprecating the policy system and looking to remove it entirely:
python/cpython#127949

[Dreamsorcerer]

I think this is closely related to #796.

That one seems to just be concerned with sync tests geting executed multiple times.

I'm also linking #1032 which argues that this kind of customization should be possible through the async marker.
For example: @pytest.mark.asyncio(policy=…).

Yes, this one may end up solving the issue.