pytest-advanced

# Advanced Pytest Patterns

Advanced pytest features for robust, maintainable test suites.

## When to Use This Skill

| Use this skill when... | Use python-testing instead when... |
|------------------------|-------------------------------------|
| Writing fixtures with scopes/factories | Basic test structure questions |
| Parametrizing with complex data | Simple assert patterns |
| Setting up pytest plugins (cov, xdist) | Running existing tests |
| Organizing conftest.py hierarchy | Test discovery basics |
| Async testing with pytest-asyncio | Synchronous unit tests |

## Installation

```bash
# Core + common plugins
uv add --dev pytest pytest-cov pytest-asyncio pytest-xdist pytest-mock
```

## Configuration (pyproject.toml)

```toml
[tool.pytest.ini_options]
testpaths = ["tests"]
addopts = [
    "-v",
    "--strict-markers",
    "--tb=short",
    "-ra",
    "--cov=src",
    "--cov-report=term-missing",
    "--cov-fail-under=80",
]
markers = [
    "slow: marks tests as slow (deselect with '-m \"not slow\"')",
    "integration: marks tests as integration tests",
]
asyncio_mode = "auto"

[tool.coverage.run]
branch = true
source = ["src"]

[tool.coverage.report]
exclude_lines = ["pragma: no cover", "if TYPE_CHECKING:", "@abstractmethod"]
```

## Fixtures

### Scopes and Lifecycle

```python
import pytest
from typing import Generator

# function (default) - fresh per test
@pytest.fixture
def db() -> Generator[Database, None, None]:
    database = Database(":memory:")
    database.create_tables()
    yield database
    database.close()

# session - shared across all tests
@pytest.fixture(scope="session")
def app():
    return create_app("testing")

# autouse - applies automatically
@pytest.fixture(autouse=True)
def reset_state():
    clear_cache()
    yield
```

| Scope | Lifetime |
|-------|----------|
| `function` | Each test (default) |
| `class` | Each test class |
| `module` | Each test file |
| `session` | Entire test run |

### Parametrized Fixtures

```python
@