使用pytest的异步装置

Question

如何定义异步fixture并在异步测试中使用它们？

下面的代码都在同一个文件中，非常失败。是否测试运行者直接调用了fixture，而不是等待它？

@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

我知道我也许能做到

@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一种更简单/最优雅的方式。我在pytest、pytest-asyncio、pytest-aiohttp的项目页面中都找不到清晰而简单的示例/解释。

我使用的是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在事件循环中运行测试，而不是直接调用它。

可以将这些设备标记为正常

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

Answer 2

PyTest本身并不支持协程函数，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'))

主要思想是使用异步fixtures将使用的同步loop-fixture

Answer 3

将此代码放在conftest.py中，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)