unittest

Python's built-in unit testing framework (originally called PyUnit) provides a structured, object-oriented approach to test automation, fixtures, and test suites.

Inspired by JUnit, unittest is Python's standard library solution for verifying code correctness. Developers subclass unittest.TestCase to write individual test methods, leveraging built-in assertions like assertEqual() and assertTrue() to validate behavior. The framework manages test execution lifecycles through setUp() and tearDown() fixtures, allowing clean environment preparation and resource disposal for each run. Because it is built directly into Python, it requires zero external dependencies and integrates seamlessly with popular third-party runners like pytest.

https://docs.python.org/3/library/unittest.html