This works for me, please try:
import asyncio
import pytest
pytest_plugins = ('pytest_asyncio',)
@pytest.mark.asyncio
async def test_simple():
await asyncio.sleep(0.5)
Output of pytest -v
confirms it passes:
collected 1 item
test_async.py::test_simple PASSED
And I have installed:
pytest 6.2.5
pytest-asyncio 0.16.0
# anyio not installed