[英]How to timeout an async test in pytest with fixture?
我正在測試可能會死鎖的異步 function。 我試圖添加一個夾具來限制 function 在引發故障之前只運行 5 秒,但到目前為止還沒有奏效。
設置:
pipenv --python==3.6
pipenv install pytest==4.4.1
pipenv install pytest-asyncio==0.10.0
代碼:
import asyncio
import pytest
@pytest.fixture
def my_fixture():
# attempt to start a timer that will stop the test somehow
asyncio.ensure_future(time_limit())
yield 'eggs'
async def time_limit():
await asyncio.sleep(5)
print('time limit reached') # this isn't printed
raise AssertionError
@pytest.mark.asyncio
async def test(my_fixture):
assert my_fixture == 'eggs'
await asyncio.sleep(10)
print('this should not print') # this is printed
assert 0
--
編輯:Mikhail 的解決方案工作正常。 不過,我找不到將它合並到夾具中的方法。
使用超時限制功能(或代碼塊)的便捷方法是使用async-timeout模塊。 您可以在測試函數中使用它,或者,例如,創建一個裝飾器。 與夾具不同,它允許為每個測試指定具體時間:
import asyncio
import pytest
from async_timeout import timeout
def with_timeout(t):
def wrapper(corofunc):
async def run(*args, **kwargs):
with timeout(t):
return await corofunc(*args, **kwargs)
return run
return wrapper
@pytest.mark.asyncio
@with_timeout(2)
async def test_sleep_1():
await asyncio.sleep(1)
assert 1 == 1
@pytest.mark.asyncio
@with_timeout(2)
async def test_sleep_3():
await asyncio.sleep(3)
assert 1 == 1
為具體時間創建裝飾器並不困難( with_timeout_5 = partial(with_timeout, 5)
)。
我不知道如何創建紋理(如果你真的需要夾具),但上面的代碼可以提供起點。 也不確定是否有一種共同的方法來更好地實現目標。
有一種方法可以使用fixtures進行超時,只需要在conftest.py
添加以下鈎子conftest.py
。
timeout
為前綴的夾具都必須返回測試可以運行的秒數( int
, float
)。autouse
裝置的優先級低於明確選擇的裝置。 后一種是首選。 不幸的是,函數參數列表中的順序並不重要。pytest.mark.asyncio
標記,但無論如何這是必需的。# Add to conftest.py
import asyncio
import pytest
_TIMEOUT_FIXTURE_PREFIX = "timeout"
@pytest.hookimpl(tryfirst=True, hookwrapper=True)
def pytest_runtest_setup(item: pytest.Item):
"""Wrap all tests marked with pytest.mark.asyncio with their specified timeout.
Must run as early as possible.
Parameters
----------
item : pytest.Item
Test to wrap
"""
yield
orig_obj = item.obj
timeouts = [n for n in item.funcargs if n.startswith(_TIMEOUT_FIXTURE_PREFIX)]
# Picks the closest timeout fixture if there are multiple
tname = None if len(timeouts) == 0 else timeouts[-1]
# Only pick marked functions
if item.get_closest_marker("asyncio") is not None and tname is not None:
async def new_obj(*args, **kwargs):
"""Timed wrapper around the test function."""
try:
return await asyncio.wait_for(
orig_obj(*args, **kwargs), timeout=item.funcargs[tname]
)
except Exception as e:
pytest.fail(f"Test {item.name} did not finish in time.")
item.obj = new_obj
@pytest.fixture
def timeout_2s():
return 2
@pytest.fixture(scope="module", autouse=True)
def timeout_5s():
# You can do whatever you need here, just return/yield a number
return 5
async def test_timeout_1():
# Uses timeout_5s fixture by default
await aio.sleep(0) # Passes
return 1
async def test_timeout_2(timeout_2s):
# Uses timeout_2s because it is closest
await aio.sleep(5) # Timeouts
可能不適用於其他一些插件,我只用pytest-asyncio
對其進行了測試,如果item
被某些鈎子重新定義,它肯定不起作用。
我只是喜歡Quimby 用超時標記測試的方法。 這是我改進它的嘗試,使用pytest 標記:
# tests/conftest.py
import asyncio
@pytest.hookimpl(tryfirst=True, hookwrapper=True)
def pytest_pyfunc_call(pyfuncitem: pytest.Function):
"""
Wrap all tests marked with pytest.mark.async_timeout with their specified timeout.
"""
orig_obj = pyfuncitem.obj
if marker := pyfuncitem.get_closest_marker("async_timeout"):
async def new_obj(*args, **kwargs):
"""Timed wrapper around the test function."""
try:
return await asyncio.wait_for(orig_obj(*args, **kwargs), timeout=marker.args[0])
except (asyncio.CancelledError, asyncio.TimeoutError):
pytest.fail(f"Test {pyfuncitem.name} did not finish in time.")
pyfuncitem.obj = new_obj
yield
def pytest_configure(config: pytest.Config):
config.addinivalue_line("markers", "async_timeout(timeout): cancels the test execution after the specified amount of seconds")
用法:
@pytest.mark.asyncio
@pytest.mark.async_timeout(10)
async def potentially_hanging_function():
await asyncio.sleep(20)
將它包含到pytest-asyncio
上的asyncio
標記中應該不難,因此我們可以獲得如下語法:
@pytest.mark.asyncio(timeout=10)
async def potentially_hanging_function():
await asyncio.sleep(20)
編輯:看起來已經有一個 PR 。
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