Introduction to pytest: Installation, Usage, and Advanced Features

pytest is a Python unit‑testing framework that offers a simpler, more efficient alternative to the built‑in unittest module, featuring easy onboarding, rich documentation, parameterization, selective test skipping, repeat‑run of failures, compatibility with nose/unittest tests, and extensive third‑party plugins.

Installation : run pip install -U pytest to upgrade to the latest version, then verify with pytest --version .

Basic usage : create a source file (e.g., caculate.py ) with functions, then write test cases in test_demo01.py . Execute with pytest -v test_demo01.py to see detailed results.

Class‑based tests : define a class in test_demo02.py and place test methods inside; pytest will run all methods automatically.

Execution options and discovery rules : use pytest -v for verbose output, pytest -s to show prints, pytest -q for quiet mode; pytest discovers files matching test_*.py or *_test.py and classes prefixed with Test and methods prefixed with test_ .

Assertions and markers : pytest relies on Python's assert statement for checks; you can skip tests with @pytest.mark.skip , mark expected failures with @pytest.mark.xfail , and select subsets using custom markers (e.g., pytest -m android ).

Fixtures : define reusable setup/teardown logic in functions decorated with @pytest.fixture . Control their scope (function, class, module, session) to manage when they run; place common fixtures in conftest.py for global availability.

Plugins : enhance pytest with plugins such as pytest‑sugar (colorful output), pytest‑xdist (parallel execution), pytest‑ordering (control order), and pytest‑assume (continue after multiple assertion failures). Install plugins via pip install plugin-name .