Testing

General

Type of tests:

• Unit test: testing of individual units of source code (scripts, functions, classes).
• Integration test: testing of a combination of individual units as a group.
• Regression test: re-running all tests to ensure that the previously developed and tested code still performes after a code change.

Writing tests

pytest supports execution of unittest test cases. The real advantage of pytest comes by writing pytest test cases. pytest test cases are a series of functions in a Python file starting with the name test_.

pytest has some other great features:

• Support for the built-in assert statement instead of using special self.assert*() methods
• Support for filtering for test cases
• Ability to rerun from the last failing test
• An ecosystem of hundreds of plugins to extend the functionality

Writing the sum test case example for pytest would look like this:

def test_sum():
    assert sum([1, 2, 3]) == 6, "Should be 6"

def test_sum_tuple():
    assert sum((1, 2, 3)) == 6, "Should be 6"

Some general best practices:

• Name of the test file should be the name of the function you want to test, prefixed by test_. Pytest will automatically recognize all tests with this convention.
• Tests should be independent and never depend on another test/
• Test for edge cases

Executing tests

Code coverage

Code coverage measures the percentage of code under tests. A good goal would be to have at least 80% of the code base under unit testing.

• Make use of SonarCloud

Continuous Integration

• Use GitHub Actions for running tests (https://docs.github.com/en/actions/guides/building-and-testing-python)

Resources

• https://realpython.com/python-testing/
• https://realpython.com/pytest-python-testing/
• https://www.tutorialspoint.com/pytest/pytest_quick_guide.htm
• https://docs.pytest.org/en/6.2.x/goodpractices.html