test — Regression tests package for Python

The test package contains all regression tests for Python as well as the modules test.support and test.regrtest. test.support is used to enhance your tests while test.regrtest drives the testing suite.

unittest.mock — mock object library

Source code: Lib/unittest/mock.py

unittest — Unit testing framework

Source code: Lib/unittest/__init__.py

pydoc — Documentation generator and online help system

Source code: Lib/pydoc.py

Python Development Mode

The Python Development Mode introduces additional runtime checks that are too expensive to be enabled by default. It should not be more verbose than the default if the code is correct; new warnings are only emitted when an issue is detected.

typing — Support for type hints

Source code: Lib/typing.py

doctest — Test interactive Python examples

Source code: Lib/doctest.py