Pytest hook to mark all async tests with scope=session not working when using async fixtures

[albertferras-vrf]

I have followed instructions from https://pytest-asyncio.readthedocs.io/en/latest/how-to-guides/run_session_tests_in_same_loop.html to add the pytest.mark.asyncio(scope="session") to all my async tests.

The problem I'm having is that, when these tests contain an async session-scoped fixture, the tests fail with RunTimeError: Event loop is closed.
If I manually add the @pytest.mark.asyncio(scope="session") mark on my tests (one by one, without using the pytest hook) then it works fine.

This reproduces the issue. Using pytest-asyncio==0.23.2 and pytest==7.4.3 on python 3.11.16. I also have asyncio_mode=auto in case it's relevant

conftest.py

import pytest
from pytest_asyncio import is_async_test


def pytest_collection_modifyitems(items):
    pytest_asyncio_tests = (item for item in items if is_async_test(item))
    session_scope_marker = pytest.mark.asyncio(scope="session")
    for async_test in pytest_asyncio_tests:
        async_test.add_marker(session_scope_marker)

test_hello.py

import pytest
import asyncio


@pytest.fixture
def get_marks(request):
    marks = [repr(m) for m in request.node.iter_markers()]
    if request.node.parent:
        marks += [repr(m) for m in request.node.parent.iter_markers()]
    yield marks


@pytest.fixture(scope="session")
async def myfixture():
    await asyncio.sleep(0.1)
    yield 5


async def test_one(get_marks, myfixture):
    print(get_marks)
    await asyncio.sleep(0.1)
    assert True


async def test_two(get_marks, myfixture):
    print(get_marks)
    await asyncio.sleep(0.1)
    assert True

[seifertm]

Thanks for the report and the great reproducer!
There seem to be two independent issues:

1. Some asyncio markers have incorrect scope
2. The fixture finalizer for myfixture is not run properly

When I change myfixture to return 5, rather than yield 5, the tests pass.

I have to investigate with regards to both problems.

[seifertm]

Regarding your workaround: Rather than marking each test individually, you could consider marking modules or even packages using pytestmark, until this is fixed.

See also:
How to run all tests in a module in the same event loop
How to run all tests in a package in the same event loop

[albertferras-vrf]

Thanks for the quick response.

I have tried marking it by package (pytestmark = pytest.mark.asyncio(scope="package") on the __init__.py of every directory with tests). but it does not work. I'm getting

E   pytest_asyncio.plugin.MultipleEventLoopsRequestedError: Multiple asyncio event loops with different scopes have been requested
E   by tests/integration/test_xxxx.py::test_xxxxxxx. The test explicitly requests the event_loop fixture, while
E   another event loop with module scope is provided by tests/integration/test_xxxx.py.
E   Remove "event_loop" from the requested fixture in your test to run the test
E   in a module-scoped event loop or remove the scope argument from the "asyncio"
E   mark to run the test in a function-scoped event loop.```

I believe it's because I have some fixtures defined at `tests/conftest.py` that are used inside `tests/integrations/` package

[SavchenkoValeriy]

First of all, thank for this package and for maintaining it! ❤️

When I change myfixture to return 5, rather than yield 5, the tests pass.

Here I just want to add that it's not always possible to switch from yield to return, e.g. if the fixture uses context manager (the actual problem that I have now).

[seifertm]

@albertferras-vrf The MultipleEventLoopsRequestedError is raised when a test is marked with @pytest.mark.asyncio(scope=…) and the test simultaneously requests the event_loop fixture in its function arguments.
In this case, pytest-asyncio cannot decide whether the test should run in the event loop associated with the scope kwarg or in the loop provided by the event_loop fixture.

[albertferras-vrf]

@seifertm the thing is that I have no test explicitly requesting the event_loop fixture in any of my tests.
Might be because I have this in the root conftest.py and it's trying to use this eventloop, which is what I want, because I have fixtures on root conftest.py that I need on this directory. Pretty similar to #706 (comment)

@pytest.fixture(scope="session")
def event_loop_policy(request):
    return CustomEventLoopPolicy()

[WolfgangFellger]

Chiming in to say that I too have gotten MultipleEventLoopsRequestedError, when no test in the codebase (and certainly not the one reported in the message) requests event_loop explicitly. Only fixtures do that. Sadly it refuted attempts to reproduce so far – if I remove the code and copy the involved fixture tree into a single file it works :-/