FastAPI async tests skipped: pytest-asyncio "asyncio_mode" not set in CI

pytest-asyncio only runs async def tests when a mode is configured. If asyncio_mode is unset, async tests are collected but not awaited, so they emit a "coroutine was never awaited" warning and silently pass without executing assertions.

What this error means

CI is green but async FastAPI tests never actually run: you see "PytestUnhandledCoroutineWarning" or "coroutine ... was never awaited", and asserting a failure does not fail the build.

python

PytestUnraisableExceptionWarning: ...
RuntimeWarning: coroutine 'test_create_item' was never awaited
  warnings.warn(...)

Common causes

asyncio_mode is not configured

With the default strict mode and no per-test markers, or no mode at all, pytest-asyncio does not run the coroutine tests.

Missing per-test asyncio markers in strict mode

In strict mode each async test needs @pytest.mark.asyncio; unmarked ones are not awaited.

How to fix it

Set asyncio_mode in config

Configure the mode so async tests are awaited without a marker on every test.

pyproject.toml

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

Or mark each async test in strict mode

If you keep strict mode, mark every coroutine test so it runs.

tests/test_api.py

import pytest

@pytest.mark.asyncio
async def test_create_item():
    ...

How to prevent it

Set asyncio_mode in pyproject or pytest.ini so async tests always run.
Fail the build on "coroutine was never awaited" warnings with a filter.
Assert a known failure once to confirm async tests actually execute.