PY-TEST0009 · synchronous_test_asyncio_run_count

Count asyncio.run calls owned by synchronous pytest tests.

This is a deterministic rule for python. Read its implementation.

Definition

Resolve ordinary and aliased imports of asyncio.run in modules matching pytest’s default collection conventions. Report each direct call owned by a synchronous collected test. Calls inside a nested helper scope are independent and are not attributed to the test.

Evidence

Each finding identifies the collected test and exact runner call. The rule does not match an unrelated local function named run or a same-named parameter that shadows an import. The value is the number of runner calls owned by a synchronous collected test.

Exceptions

asyncio.run remains appropriate at an application entry point. In pytest, prefer an async test owned by AnyIO or pytest-asyncio so the plugin controls event-loop isolation, fixtures, cancellation, and cleanup. Ruff’s PT rules do not check event-loop ownership.

Examples

Bad

def test_fetch():
    response = asyncio.run(fetch())
    assert response.status == 200

Good

@pytest.mark.anyio
async def test_fetch():
    response = await fetch()
    assert response.status == 200

References

• Cites “The Python Standard Library”, asyncio runners. Open reference
• Cites “AnyIO documentation”, asynchronous tests. Open reference
• Cites “pytest-asyncio documentation”, test discovery modes. Open reference