使用 pytest 的异步装置

Question

如何定义异步装置并在异步测试中使用它们？

以下代码都在同一个文件中，但失败得很惨。 fixture 是否由测试运行器直接调用而不等待？

@pytest.fixture
async def create_x(api_client):
    x_id = await add_x(api_client)
    return api_client, x_id

async def test_app(create_x, auth):
    api_client, x_id = create_x
    resp = await api_client.get(f'my_res/{x_id}', headers=auth)
    assert resp.status == web.HTTPOk.status_code

生产

==================================== ERRORS ====================================
_____________ ERROR at setup of test_app[pyloop] ______________

api_client = <aiohttp.test_utils.TestClient object at 0x7f27ec954f60>

    @pytest.fixture
    async def create_x(api_client):
>       x_id = await add_x(api_client)
...
... cannot show the full trace and pathnames sorry
...    

in __await__
    ret = yield from self._coro /home/mbb/.pyenv/versions/3.6.3/envs/mr/lib/python3.6/site-packages/aiohttp/test_utils.py:245: in request
    method, self.make_url(path), *args, **kwargs /home/mbb/.pyenv/versions/mr/lib/python3.6/site-packages/aiohttp/helpers.py:104: in __iter__
    ret = yield from self._coro /home/mbb/.pyenv/versions/mr/lib/python3.6/site-packages/aiohttp/client.py:221: in _request
    with timer:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <aiohttp.helpers.TimerContext object at 0x7f27ec9875c0>

    def __enter__(self):
        task = current_task(loop=self._loop)

        if task is None:
>           raise RuntimeError('Timeout context manager should be used '
                               'inside a task') E           RuntimeError: Timeout context manager should be used inside a task

/home/mbb/.pyenv/versions/mr/lib/python3.6/site-packages/aiohttp/helpers.py:717: RuntimeError
=========================== 1 error in 1.74 seconds ============================ Process finished with exit code 0

我知道我可能会做

@pytest.fixture
def create_x(loop, api_client):
    x_id = loop.run_until_complete(add_x(api_client))
    return api_client, x_id

但我想知道是否存在 easier/most 优雅的方法。我在 pytest、pytest-asyncio、pytest-aiohttp 的项目页面中找不到清晰简单的 example/explanation。

我使用 Python 3.6.3、pytest 3.4.2、pytest-asyncio 0.8.0 和 pytest-aiohttp 0.3.0

非常感谢您的帮助

Answer 1

您只需将测试标记为异步

@pytest.mark.asyncio
async def test_app(create_x, auth):
    api_client, x_id = create_x
    resp = await api_client.get(f'my_res/{x_id}', headers=auth)
    assert resp.status == web.HTTPOk.status_code

这告诉 pytest 运行事件循环内的测试而不是直接调用它。

灯具可以标记为正常

@pytest.fixture
async def create_x(api_client):
    x_id = await add_x(api_client)
    return api_client, x_id

Answer 2

PyTest 本身不支持协程函数，因此您需要为其安装额外的框架

pytest-aiohttp
pytest-asyncio
pytest-trio
pytest-tornasync

如果你使用pytest-aiohttp，你的问题就这样解决了

import asyncio
import pytest

from app import db


url = 'postgresql://postgres:postgres@localhost:5432'


@pytest.fixture(scope='session')
def loop():
    return asyncio.get_event_loop()


@pytest.fixture(scope='session', autouse=True)
async def prepare_db(loop):
    async with db.with_bind(f'{url}/postgres') as engine:
        await engine.status(db.text('CREATE DATABASE test_db'))

    await db.set_bind(f'{url}/test_db')
    await db.gino.create_all()

    yield
    await db.bind.close()

    async with db.with_bind(f'{url}/postgres') as engine:
        await engine.status(db.text('DROP DATABASE test_db'))

主要思想是使用同步 loop-fixture 异步装置

Answer 3

将其放入 conftest.py 以标记所有异步函数：

import inspect
import pytest

def pytest_collection_modifyitems(config, items):
    for item in items:
        if inspect.iscoroutinefunction(item.function):
            item.add_marker(pytest.mark.asyncio)

Answer 4

with pytest-asyncio 如果您将以下内容添加到您的 pytest.ini 配置文件中，则无需标记：

# pytest.ini
[pytest]
...
asyncio_mode=auto
...

添加了这个后，您可以只需要异步语法就可以创建一个异步夹具和测试

# test_file.py
import pytest
from some-aio-library import AsyncClient

@pytest.fixture
async def test_async_client():
    async with AsyncClient() as client:
        yield client


async def test_something(test_async_client: AsyncClient):
    result = await test_async_client.get_some_data()
    
    assert result.data == "some data"

使用 pytest 的异步装置

Async fixtures with pytest

pytest

python-3.x

python-asyncio

pytest-aiohttp

pytest-asyncio