python - 如何使用 pytest 中的 setUp 作为异步方法？

Question

我有以下代码:

import asyncio
import pytest

from mymodule import myasyncfunction
from unittest import TestCase


class TestDummy(TestCase):
    def setUp(self):
        await myasyncfunction()

    @pytest.mark.asyncio
    async def test_dummy(self):
        assert False

测试通过，因为它根本没有进入测试。它只说:

RuntimeWarning: coroutine 'TestDummy.setUp' was never awaited

如何使setUp函数异步？

观察:如果我从 TestCase 中删除继承，测试会运行，但之前不会进入 setUp 函数，这是需要的。

Answer 1

解决方案是将方法定义为fixture，而不是使用传统的setUp() 方法。

import pytest

class TestClass:
    @pytest.fixture
    def setup(self):
        pass

    @pytest.mark.asyncio
    async def test_some_stuff(setup):
        pass

正如您所发现的，当类继承自 Unitest.Testcase 时，使用 pytest-asyncio setUp() 方法不起作用:

TestPersonClass is not a child class of unittest.TestCase. If it was, the test would still succeed – but the success would be a false positive because code after the await expression would not run.

Why is this happening? The answer is complex enough that it deserves a separate post, but the tl;dr version is that on line 93 of pytest-asyncio’s source the author is expecting the event loop to be passed into the test from a pytest fixture, while unittest.TestCase methods cannot directly receive fixture function arguments.

有关上述解释，请参阅本博客文章的结尾:
https://jacobbridges.github.io/post/unit-testing-with-asyncio/

有关使用 pytest-asyncio 进行测试的一些不错的教程，请参阅:
1) https://www.roguelynn.com/words/asyncio-testing/
2) https://medium.com/ideas-at-igenius/testing-asyncio-python-code-with-pytest-a2f3628f82bc