Pytest: Allow coroutine fixtures

[k4nar]

pytest-asyncio provides a very nice feature, which is to allow coroutine fixtures. For example it makes possible to create a fixture making asynchronous DB requests.

Unfortunately pytest-asyncio and pytest-aiohttp seems to no longer be compatible. So far this is the only feature that I'm missing, so it would be awesome if it were added to pytest-aiohttp.

Here is the implementation in pytest-asyncio:
https://github.com/pytest-dev/pytest-asyncio/blob/92b34e5e9a14c45062d6ce2e2686ed8b11c7c03e/pytest_asyncio/plugin.py#L52-L134

I've tried to adapt it to pytest-aiohttp but unsuccessfully so far.

[samuelcolvin]

It's very simple right now to create fixtures which execute asynchronous code, for example:

@pytest.yield_fixture
def redis(loop):
    async def _redis():
        redis = await create_redis(('localhost', 6379))
        await redis.flushdb()
        return redis

    redis = loop.run_until_complete(_redis())

    yield redis

    async def _close():
        redis.close()
        await redis.wait_closed()
    loop.run_until_complete(_close())

[samuelcolvin]

Personally I think the way aiohttp executes async tests is good and I think @asvetlov built it this way specifically because he didn't agree with how pytest-asyncio was setup.

[k4nar]

Yes, I know that it's possible to execute asynchronous code in a fixture as in your example, however I find that it's a bit too much boilerplate.

Actually I've managed to adapt pytest-asyncio's hack to pytest-aiohttp, I'll open a PR shortly.

[samuelcolvin]

so what happens with fixtures which are session scoped? Is the same loop running thoughout all tests?

From my understanding, accepting this kind of fixture in aiohttp without hacks would require a big change.

[k4nar]

It only works for function fixtures as it implies the usage of the loop fixture. So far what I have is not intrusive, it's just a pytest hook (mostly like the one in pytest-asyncio). I'm currently writing tests for it.