What is async testing in pytest?

Question

Accepted Answer

**pytest-asyncio** allows testing **async functions** with pytest.

```python
import pytest
import asyncio
from httpx import AsyncClient

# Install: pip install pytest-asyncio

# Mark test as async
@pytest.mark.asyncio
async def test_fetch_data():
    async with AsyncClient() as client:
        response = await client.get("http://localhost:8000/api/items")
        assert response.status_code == 200
        assert len(response.json()) > 0

# Async fixture
@pytest.fixture
async def async_db():
    db = await create_async_engine()
    yield db
    await db.dispose()

@pytest.mark.asyncio
async def test_create_user(async_db):
    user = User(name="Alice")
    async_db.add(user)
    await async_db.commit()
    result = await async_db.get(User, user.id)
    assert result.name == "Alice"

# Async mock
@pytest.mark.asyncio
async def test_with_mock():
    with patch("mymodule.fetch") as mock_fetch:
        mock_fetch.return_value = {"data": "test"}
        result = await my_async_function()
        assert result == {"data": "test"}

# conftest.py — async fixture for entire session
@pytest.fixture(scope="session")
async def event_loop():
    loop = asyncio.get_event_loop_policy().new_event_loop()
    yield loop
    loop.close()
```

**Configuration (pytest.ini):**
```ini
[pytest]
asyncio_mode = auto
```

Python: What is async testing in pytest?