A sample project for unit tests lesson

Unit test technologies

1. pytest (https://docs.pytest.org/en/6.2.x/)
2. coverage (https://pypi.org/project/pytest-cov/)
3. time freezing (https://pypi.org/project/immobilus/)
4. snapshots (https://pypi.org/project/snapshottest/)
5. factories (https://factoryboy.readthedocs.io/en/stable/, https://faker.readthedocs.io/en/master/)
6. mocks (https://pypi.org/project/pytest-mock/, https://devdocs.io/python~3.9/library/unittest.mock)
   1. patch with return
   2. patch with exception