pytest¶

pytest is an alternative to Python’s Unittest module that simplifies testing even further.

pytest automatically recognises tests based on filenames and functions that start with test_, while unittest derives test classes and methods from unittest.TestCase. This results in simpler, more readable syntax with less boilerplate code.
unittest provides a set of assertion methods (for example, assertEqual(), assertTrue(), assertRaises()). With pytest, the same assertions can be defined, but using Python’s standard assert() statement. This often results in more meaningful error messages and better introspection.
unittest only provides setUp() and tearDown() methods for fixtures. In pytest, on the other hand, fixtures are defined as functions, which promotes reusability and simplifies the management of test dependencies.
Parametrised tests are possible in unittest, but require additional effort. pytest, however, includes the decorator @pytest.mark.parametrize, which makes it easy to run test functions with different inputs and expected outputs.
pytest has an extensive ecosystem with over 800 Plugins for advanced testing requirements; unittest is more limited in its extensibility.

Installation¶

You can install pytest in virtual environments <venv> with:

Linux/macOS

$ python -m pip install pytest
Collecting pytest
...
Successfully installed attrs-21.2.0 iniconfig-1.1.1 pluggy-1.0.0 py-1.10.0 pytest-6.2.5 toml-0.10.2

Windows

C:> python -m pip install pytest
Collecting pytest
...
Successfully installed attrs-21.2.0 iniconfig-1.1.1 pluggy-1.0.0 py-1.10.0 pytest-6.2.5 toml-0.10.2