pytest-asyncio tests not running async - pytest

Question

I'm trying to implement a simple async test suite. If my understanding is correct of async, the tests below should only take about 2 seconds to run. However, it's taking 6 seconds. What am I missing to make these test to run async ("at the same time")?
import logging
import pytest
import asyncio
MSG_FORMAT = "%(asctime)s.%(msecs)03d %(module)s->%(funcName)-15s |%(levelname)s| %(message)s"
MSG_DATE_FORMAT = "%Y-%m-%d %H:%M:%S"
LOG_LEVEL = logging.INFO
# Create logger
logger = logging.getLogger(__name__)
logger.setLevel(LOG_LEVEL)
# Create Stream Handler
log_stream = logging.StreamHandler()
log_format = logging.Formatter(fmt=MSG_FORMAT, datefmt=MSG_DATE_FORMAT)
log_stream.setFormatter(log_format)
log_stream.setLevel(LOG_LEVEL)
logger.addHandler(log_stream)
class TestMyStuff:
#staticmethod
async def foo(seconds):
await asyncio.sleep(seconds)
return 1
#pytest.mark.asyncio
async def test_1(self, event_loop):
logger.info("start")
assert await event_loop.create_task(self.foo(2)) == 1
logger.info("end")
#pytest.mark.asyncio
async def test_2(self, event_loop):
logger.info("start")
assert await event_loop.create_task(self.foo(2)) == 1
logger.info("end")
#pytest.mark.asyncio
async def test_3(self, event_loop):
logger.info("start")
# assert await event_loop.run_in_executor(None, self.foo) == 1
assert await event_loop.create_task(self.foo(2)) == 1
logger.info("end")
pytest extras:
plugins: asyncio-0.18.3, aiohttp-1.0.4

Answer 1

pytest-asyncio runs asynchronous tests serially. That plugin's goal is to make testing asynchronous code more convenient.
pytest-asyncio-cooperative on the other hand has the goal of running asyncio tests concurrently via cooperative multitasking (ie. all async coroutines sharing the same event loop and yielding to each other).
To try out pytest-asyncio-cooperative do the following:
Install the plugin
pip install pytest-asyncio-cooperative
Replace the #pytest.mark.asyncio marks with #pytest.mark.asyncio_cooperative
Remove all references to event_loop. pytest-asyncio-cooperative uses a single implicit event loop for asyncio interactions.
Run pytest with pytest-asyncio disabled. It is not compatible with pytest-asyncio-cooperative
pytest -p no:asyncio test_mytestfile.py
Here is the original code snippet with these modifications:
import logging
import pytest
import asyncio
MSG_FORMAT = "%(asctime)s.%(msecs)03d %(module)s->%(funcName)-15s |%(levelname)s| %(message)s"
MSG_DATE_FORMAT = "%Y-%m-%d %H:%M:%S"
LOG_LEVEL = logging.INFO
# Create logger
logger = logging.getLogger(__name__)
logger.setLevel(LOG_LEVEL)
# Create Stream Handler
log_stream = logging.StreamHandler()
log_format = logging.Formatter(fmt=MSG_FORMAT, datefmt=MSG_DATE_FORMAT)
log_stream.setFormatter(log_format)
log_stream.setLevel(LOG_LEVEL)
logger.addHandler(log_stream)
class TestMyStuff:
#staticmethod
async def foo(seconds):
await asyncio.sleep(seconds)
return 1
#pytest.mark.asyncio_cooperative
async def test_1(self):
logger.info("start")
assert await self.foo(2) == 1
logger.info("end")
#pytest.mark.asyncio_cooperative
async def test_2(self):
logger.info("start")
assert await self.foo(2) == 1
logger.info("end")
#pytest.mark.asyncio_cooperative
async def test_3(self):
logger.info("start")
# assert await event_loop.run_in_executor(None, self.foo) == 1
assert await self.foo(2) == 1
logger.info("end")
And here are the test results:
plugins: hypothesis-6.39.4, asyncio-cooperative-0.28.0, anyio-3.4.0, typeguard-2.12.1, Faker-8.1.0
collected 3 items
test_mytestfile.py ... [100%]
================================ 3 passed in 2.18s =================================
Please checkout the README of pytest-asyncio-cooperative. Now that tests are run in a concurrent way you need to be wary of shared resources (eg. mocking)