Building Custom PyTest Plugins

Advanced PyTest Framework Extension Guide

Pytest’s plugin architecture enables powerful test framework customization. This guide demonstrates how to create custom plugins that extend pytest’s capabilities while maintaining code organization and reusability.

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Plugin Architecture in Pytest

Core Components

The plugin system is built on these key components:

# plugin_example.py
import pytest
from typing import Optional, List

def pytest_configure(config: pytest.Config) -> None:
    """Plugin configuration hook."""
    config.addinivalue_line(
        "markers",
        "custom_marker: mark test with custom functionality"
    )
def pytest_addoption(parser: pytest.Parser) -> None:
    """Add custom command line options."""
    parser.addoption(
        "--custom-option",
        action="store",
        default=None,
        help="Custom plugin option"
    )
class Plugin:
    @pytest.hookimpl
    def pytest_collection_modifyitems(
        self,
        session: pytest.Session,
        config: pytest.Config,
        items: List[pytest.Item]
    ) -> None:
        """Modify test collection."""
        pass

Hook Implementation