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pytest

pytest

github.com/microsoftTesting & quality2.5k65 installsUpdated today
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About pytest

The pytest skill provides guidance for writing and organizing tests with pytest. It covers fixtures, parametrization, assertions, plugins, and practices for keeping tests isolated and focused on observable behavior.

Key features

  1. 01Organize tests by source structure
  2. 02Choose fixture scopes and share fixtures
  3. 03Use parametrization with readable IDs
  4. 04Apply assertion and exception-testing patterns
  5. 05Select common pytest plugins

Use cases

  1. 01Structure tests in a Python project
  2. 02Test multiple inputs with parametrized cases
  3. 03Set up reusable fixtures and teardown
  4. 04Avoid interdependent tests and implementation-detail assertions

Install

Copy the command and run it in a terminal.

$npx skills add https://github.com/microsoft/debugpy --skill pytest

After installing, type/pytestin Claude Code to confirm it loaded.

Details

From the project README

Skill: pytest

Best practices for writing and organizing tests with pytest including fixtures, parametrize, and plugins.

When to Use

Apply this skill when writing and organizing tests with pytest — fixtures, parametrize, markers, plugins, and test structure.

Test Organization

  • Place tests in a tests/ directory mirroring the source structure.
  • Name test files test_<module>.py and test functions test_<behavior>().
  • Group related tests in classes only when they share fixtures/setup.

Fixtures

  • Define fixtures at the narrowest scope needed (function > class > module > session).
  • Use conftest.py for shared fixtures; put it at the appropriate directory level.
  • Prefer factory fixtures over complex fixture inheritance.
  • Use yield fixtures for setup/teardown; prefer tmp_path over tempfile.

Parametrize

  • Use @pytest.mark.parametrize for data-driven tests with multiple inputs.
  • Give test IDs (ids=...) for readable test output.
  • Combine parametrize with fixtures for cross-product testing.

Assertions

  • Use plain assert statements — pytest rewrites them for clear failure messages.
  • Use pytest.raises(ExceptionType, match=...) for exception testing.
  • Use pytest.approx() for floating-point comparisons.

Plugins

  • Common plugins: pytest-cov, pytest-mock, pytest-asyncio, pytest-xdist, pytest-timeout.
  • Use pytest-mock's mocker fixture over raw unittest.mock.patch.

Pitfalls

  • Don't use session-scoped fixtures for mutable state.
  • Don't assert on implementation details — test observable behavior.
  • Avoid test interdependence; each test should be runnable in isolation.

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