A recent release of pytest-asyncio (v1.4.0) caused several tests to fail with RuntimeError: There is no current event loop in thread 'MainThread' (see comment here).

As a quick workaround, PR #17260 introduced a temporary autouse fixture to manually manage the event loop:

@pytest.fixture(autouse=True)
def set_event_loop():
    try:
        asyncio.get_running_loop()
        yield
    except RuntimeError:
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        try:
            yield
        finally:
            loop.close()
            asyncio.set_event_loop(None)

The Correct Long-Term Fix

This workaround is a stopgap. The root cause is that tests containing asynchronous code are missing the proper async def declaration and the @pytest.mark.asyncio marker.

The correct long-term solution is to properly decorate and define these tests. For example, PR #17308 resolved this error (CI run logs) by properly updating the test definitions (see commit diff).

Next Steps

Please keep this issue open until the temporary set_event_loop fixture is entirely removed from the codebase and all affected tests are properly refactored with async def and @pytest.mark.asyncio.