# pytest AI Context
Last Updated: 2025-01-06
## Framework Overview
pytest is a mature Python testing framework that makes it easy to write simple and scalable test cases. It's the de facto standard for Python testing with powerful features and extensive plugin ecosystem.
## Current Version & Features
- **Latest Version**: pytest 7.4+ (as of 2025)
- **Key Features**:
- Automatic test discovery
- Powerful assertions with detailed failure reports
- Fixtures for setup/teardown and dependency injection
- Parametrized testing
- Parallel execution with pytest-xdist
- Extensive plugin architecture
## Common Patterns in This Project
### Test Structure
```python
# tests/test_module.py
import pytest
class TestComponent:
@pytest.fixture
def setup_data(self):
"""Fixture for test data"""
return {"key": "value"}
def test_functionality(self, setup_data):
"""Test with fixture"""
assert setup_data["key"] == "value"
```
### Fixtures
```python
# conftest.py - Shared fixtures
@pytest.fixture(scope="session")
def test_db():
"""Database fixture for testing"""
db = create_test_database()
yield db
db.cleanup()
@pytest.fixture
def mock_api(monkeypatch):
"""Mock external API calls"""
def mock_response(*args, **kwargs):
return {"status": "ok"}
monkeypatch.setattr("requests.get", mock_response)
```
### Parametrized Tests
```python
@pytest.mark.parametrize("input,expected", [
("python", "python_plugin"),
("javascript", "js_plugin"),
("unknown", None),
])
def test_plugin_resolution(input, expected):
assert get_plugin(input) == expected
```
## Integration with Project
- Test files in `tests/` directory
- Base test class in `tests/base_test.py`
- Fixtures in `tests/conftest.py`
- Run with `pytest` or `make test`
- Coverage reports with pytest-cov
## Best Practices
1. **Test Organization**: Group related tests in classes
2. **Fixtures**: Use for common setup, prefer over setUp/tearDown
3. **Mocking**: Use monkeypatch or unittest.mock
4. **Assertions**: Use plain assert with descriptive messages
5. **Test Names**: Descriptive test_what_when_expected pattern
## Common Commands
```bash
# Run all tests
pytest
# Run specific test file
pytest tests/test_module.py
# Run with coverage
pytest --cov=mcp_server --cov-report=html
# Run in parallel
pytest -n auto
# Verbose output
pytest -v
# Stop on first failure
pytest -x
```
## Markers and Configuration
```python
# Custom markers
@pytest.mark.slow
def test_expensive_operation():
pass
@pytest.mark.skipif(condition, reason="...")
def test_conditional():
pass
```
## Common Issues and Solutions
1. **Import Errors**: Ensure PYTHONPATH includes project root
2. **Fixture Scope**: Understand session vs function scope
3. **Test Isolation**: Each test should be independent
4. **Async Tests**: Use pytest-asyncio for async code
5. **Database Tests**: Use transactions and rollback
## Performance Considerations
- Use pytest-xdist for parallel execution
- Minimize fixture scope where appropriate
- Mock expensive operations
- Use pytest-benchmark for performance tests
## References
- Official Docs: https://docs.pytest.org/
- Best Practices: https://docs.pytest.org/en/latest/explanation/goodpractices.html
- Fixtures: https://docs.pytest.org/en/latest/explanation/fixtures.html
- Plugins: https://docs.pytest.org/en/latest/reference/plugin_list.html
## AI Agent Notes
- Always use fixtures over manual setup/teardown
- Keep tests independent and idempotent
- Mock external dependencies
- Use descriptive test names
- Group related tests in classes
- Run tests before committing changes
---
*Updated via documentation analysis on 2025-01-06*
