使用Poetry构建Python项目时Pytest异步测试警告问题

问题场景 #

使用Poetry构建Python项目，编写了如下异步测试代码：

import httpx
import respx


@respx.mock
async def test_async_decorator():
    async with httpx.AsyncClient() as client:
        route = respx.get("https://example.org/")
        response = await client.get("https://example.org/")
        assert route.called
        assert response.status_code == 200

运行poetry run pytest或pytest时，出现警告导致测试被跳过：

test_gsx.py::test_async_decorator
  /Users/krishna/Library/Caches/pypoetry/virtualenvs/geoserverx-Yc0Bl2cH-py3.11/lib/python3.11/site-packages/_pytest/python.py:183: 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/how-to/capture-warnings.html

项目的pyproject.toml开发依赖已包含pytest-asyncio和anyio：

[tool.poetry.group.dev.dependencies]
pytest = "^7.1.2"
respx = "^0.20.1"
mypy = "^0.960"
black = "^22.3.0"
isort = "^5.10.1"
pytest-asyncio = "^0.21.0"
anyio = {extras = ["trio"], version = "^3.3.4"}

解决方案 #

• 检查插件加载状态
  运行poetry run pytest --trace-config查看已加载的插件列表，确认pytest_asyncio在输出中。如果未加载，执行poetry install --sync重新同步依赖，确保插件安装到虚拟环境中。

• 升级依赖版本
  旧版本的pytest（7.1.2）和pytest-asyncio（0.21.0）在Python 3.11下可能存在兼容性问题。修改pyproject.toml中的依赖版本：

  pytest = "^7.4.0"
  pytest-asyncio = "^0.23.0"
  

  然后执行poetry update pytest pytest-asyncio完成升级。

• 添加pytest异步模式配置
  在pyproject.toml中添加pytest配置，显式启用pytest-asyncio的自动识别模式：

  [tool.pytest.ini_options]
  asyncio_mode = "auto"
  

• 确保使用正确的虚拟环境
  避免直接运行全局的pytest，始终使用poetry run pytest来执行测试，确保调用的是虚拟环境中安装的pytest及插件。

• 调整装饰器顺序并显式标记异步测试
  在测试函数上添加@pytest.mark.asyncio装饰器，并放在@respx.mock之前，确保pytest能识别这是异步测试：

  import httpx
  import respx
  import pytest
  
  @pytest.mark.asyncio
  @respx.mock
  async def test_async_decorator():
      async with httpx.AsyncClient() as client:
          route = respx.get("https://example.org/")
          response = await client.get("https://example.org/")
          assert route.called
          assert response.status_code == 200
  

内容的提问来源于stack exchange，提问作者krishna lodha