How to test async function using pytest?
Question:
@pytest.fixture
def d_service():
c = DService()
return c
# @pytest.mark.asyncio # tried it too
async def test_get_file_list(d_service):
files = await d_service.get_file_list('')
print(files)
However, it got the following error?
collected 0 items / 1 errors
=================================== ERRORS ====================================
________________ ERROR collecting tests/e2e_tests/test_d.py _________________
..........anaconda3libsite-packagespluggy__init__.py:617: in __call__
return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
..........anaconda3libsite-packagespluggy__init__.py:222: in _hookexec
return self._inner_hookexec(hook, methods, kwargs)
..........anaconda3libsite-packagespluggy__init__.py:216: in
firstresult=hook.spec_opts.get('firstresult'),
..........anaconda3libsite-packages_pytestpython.py:171: in pytest_pycollect_makeitem
res = outcome.get_result()
..........anaconda3libsite-packagesanyiopytest_plugin.py:98: in pytest_pycollect_makeitem
marker = collector.get_closest_marker('anyio')
E AttributeError: 'Module' object has no attribute 'get_closest_marker'
!!!!!!!!!!!!!!!!!!! Interrupted: 1 errors during collection !!!!!!!!!!!!!!!!!!!
=========================== 1 error in 2.53 seconds ===========================
I installed the following package. The error is gone but the test is skipped.
pip install pytest-asyncio
(base) PS>pytest -s testse2e_teststest_d.py
================================================================================================================== test session starts ===================================================================================================================
platform win32 -- Python 3.6.4, pytest-6.2.5, py-1.11.0, pluggy-1.0.0
rootdir: C:UsersX01324908sourcerdsresearch_data_sciencesftpfile_handler
plugins: anyio-3.3.4, asyncio-0.16.0
collected 1 item
testse2e_teststest_d.py s
==================================================================================================================== warnings summary ====================================================================================================================
tests/e2e_tests/test_d.py::test_get_file_list
c:usersx01324908anaconda3libsite-packages_pytestpython.py:172: PytestUnhandledCoroutineWarning: async def functions are not natively supported and have been skipped.
You need to install a suitable plugin for your async framework, for example:
- anyio
- pytest-asyncio
- pytest-tornasync
- pytest-trio
- pytest-twisted
warnings.warn(PytestUnhandledCoroutineWarning(msg.format(nodeid)))
-- Docs: https://docs.pytest.org/en/stable/warnings.html
=============
Answers:
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
Homemade solution
A decorator that runs the test coroutine in the event loop:
import asyncio
import inspect
def asyncio_run(async_func):
def wrapper(*args, **kwargs):
return asyncio.run(async_func(*args, **kwargs))
wrapper.__signature__ = inspect.signature(async_func) # without this, fixtures are not injected
return wrapper
@asyncio_run
async def test_get_file_list(d_service):
files = await d_service.get_file_list('')
print(files)
@pytest.fixture
def d_service():
c = DService()
return c
# @pytest.mark.asyncio # tried it too
async def test_get_file_list(d_service):
files = await d_service.get_file_list('')
print(files)
However, it got the following error?
collected 0 items / 1 errors =================================== ERRORS ==================================== ________________ ERROR collecting tests/e2e_tests/test_d.py _________________ ..........anaconda3libsite-packagespluggy__init__.py:617: in __call__ return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs) ..........anaconda3libsite-packagespluggy__init__.py:222: in _hookexec return self._inner_hookexec(hook, methods, kwargs) ..........anaconda3libsite-packagespluggy__init__.py:216: in firstresult=hook.spec_opts.get('firstresult'), ..........anaconda3libsite-packages_pytestpython.py:171: in pytest_pycollect_makeitem res = outcome.get_result() ..........anaconda3libsite-packagesanyiopytest_plugin.py:98: in pytest_pycollect_makeitem marker = collector.get_closest_marker('anyio') E AttributeError: 'Module' object has no attribute 'get_closest_marker' !!!!!!!!!!!!!!!!!!! Interrupted: 1 errors during collection !!!!!!!!!!!!!!!!!!! =========================== 1 error in 2.53 seconds ===========================
I installed the following package. The error is gone but the test is skipped.
pip install pytest-asyncio
(base) PS>pytest -s testse2e_teststest_d.py ================================================================================================================== test session starts =================================================================================================================== platform win32 -- Python 3.6.4, pytest-6.2.5, py-1.11.0, pluggy-1.0.0 rootdir: C:UsersX01324908sourcerdsresearch_data_sciencesftpfile_handler plugins: anyio-3.3.4, asyncio-0.16.0 collected 1 item testse2e_teststest_d.py s ==================================================================================================================== warnings summary ==================================================================================================================== tests/e2e_tests/test_d.py::test_get_file_list c:usersx01324908anaconda3libsite-packages_pytestpython.py:172: PytestUnhandledCoroutineWarning: async def functions are not natively supported and have been skipped. You need to install a suitable plugin for your async framework, for example: - anyio - pytest-asyncio - pytest-tornasync - pytest-trio - pytest-twisted warnings.warn(PytestUnhandledCoroutineWarning(msg.format(nodeid))) -- Docs: https://docs.pytest.org/en/stable/warnings.html =============
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
Homemade solution
A decorator that runs the test coroutine in the event loop:
import asyncio
import inspect
def asyncio_run(async_func):
def wrapper(*args, **kwargs):
return asyncio.run(async_func(*args, **kwargs))
wrapper.__signature__ = inspect.signature(async_func) # without this, fixtures are not injected
return wrapper
@asyncio_run
async def test_get_file_list(d_service):
files = await d_service.get_file_list('')
print(files)