Python Unit Testing with Pytest

This skill provides a structured workflow and resources for writing effective unit tests in Python using the pytest framework.

Core Workflow

1. Setup (pytest.ini, conftest.py): If the project doesn't have a testing setup, copy the templates from the assets/ directory.
   • assets/pytest.ini: Standard pytest and coverage configuration.
   • assets/conftest.py: Reusable fixtures, including mocks for a database and an API client.
2. Create Test File: For a given source file path/to/module.py, create a corresponding test file tests/path/to/test_module.py.
   • For guidance, read references/01_organization.md.
   • Follow the naming conventions in references/02_naming_conventions.md.
3. Write Tests: Write test functions using the Arrange-Act-Assert pattern.
   • Start with a template from assets/templates/.
     • simple_test.py: For basic tests.
     • parameterized_test.py: For testing with multiple inputs.
     • mocking_test.py: For testing code with external dependencies.
4. Run and Iterate: Run pytest and use the output to refine tests. If coverage is configured, use the report to find untested code.

Reference Guides

When you need to implement a specific pattern, consult the relevant reference guide. Read them as needed.

• references/01_organization.md: How to structure your tests directory.
• references/02_naming_conventions.md: How to name test files and functions.
• references/03_fixtures.md: How to use pytest fixtures for setup and teardown.
• references/04_mocking.md: How to mock external dependencies like APIs and databases.
• references/05_parameterization.md: How to run one test with multiple different inputs.
• references/06_assertions.md: Best practices for assert statements and checking for exceptions.
• references/07_coverage.md: How to measure and interpret test coverage.

Always start by using the templates in assets/ as a base for new test files.