pytest-asyncio has a closed event loop, but only when running all tests

Question

I have a test to verify an exception is thrown from an async response, which I'm using pytest-asyncio version 0.10.0 to run.

Code is basically:

class TestThis:
    @pytest.mark.asyncio
    def test_the_thing(self):
       arg1 = "cmd"
       arg2 = "second command"
       with pytest.raises(CustomException):
           await do_thing(arg1, arg2)

Now the really weird thing is this test works fine if I run it alone, or if I run the class alone. However when I run all tests (pytest at the project root), it fails every time with a runtime error, saying the loop is closed.

So, not necessarily an answer, but the test was living in a subfolder of the tests folder Moving the test from services to the root tests, it now works? — Mathieson, Apr 05 '20 at 17:27
This might help you: https://github.com/pytest-dev/pytest-asyncio/issues/30 — Amiram, Apr 05 '20 at 18:22

RobinFrcd · Answer 1 · 2022-06-11T09:58:45.163

12

I had to tweak @matthewpark319's answer a bit, but adding a session-scoped fixture in conftest.py worked.

import asyncio

import pytest


@pytest.fixture(scope="session")
def event_loop():
    try:
        loop = asyncio.get_running_loop()
    except RuntimeError:
        loop = asyncio.new_event_loop()
    yield loop
    loop.close()

If you're using pytest-asyncio, you may also need to edit your pyproject.toml and add:

[tool.pytest.ini_options]
asyncio_mode = "auto"

edited Jun 11 '22 at 09:58

answered May 03 '22 at 19:29

RobinFrcd

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2

`loop = asyncio.get_event_loop()` yields a `DeprecationWarning: There is no current event loop` on Python 3.10. https://docs.python.org/3.10/library/asyncio-eventloop.html#asyncio.get_event_loop – gertvdijk Jun 10 '22 at 22:28
I do not know why, but this solution works only not for all my projects. – Nairum Mar 29 '23 at 19:49
I logged just to upvote this one :) – Gabriel Ferrarini Jun 22 '23 at 13:40

matthewpark319 · Accepted Answer · 2021-04-29T17:41:56.747

https://pypi.org/project/pytest-asyncio/

You can apparently override pytest-asyncio's version of the event loop fixture. They have it like this:

@pytest.fixture
def event_loop():
    loop = asyncio.get_event_loop()
    yield loop
    loop.close()

I have it like this:

@pytest.fixture
def event_loop():
    loop = asyncio.get_event_loop()
    yield loop
    cleanly_shutdown(loop)

Or in other cases like this:

@pytest.fixture
def event_loop():
    yield asyncio.get_event_loop()

def pytest_sessionfinish(session, exitstatus):
    asyncio.get_event_loop().close()

These docs are very helpful: https://docs.pytest.org/en/latest/reference/reference.html?highlight=sessionfinish#pytest.hookspec.pytest_sessionfinish

pytest-asyncio has a closed event loop, but only when running all tests

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