15.6 Unit testing with the pytest module

The pytest tool allows us to step beyond the examples used by doctest in docstrings. Instead of using a subclass of TestCase, the pytest tool lets us use function definitions. The pytest approach uses Python’s built-in assert statement, leaving the test case looking somewhat simpler.

The pytest tool is not part of Python; it needs to be installed separately. Use a command like this:

(cookbook3) % python -m pip install pytest

In this recipe, we’ll look at how we can use pytest to simplify our test cases.

15.6.1 Getting ready

The Gherkin language can help to structure a test. For this recipe, we have a scenario like this:

Scenario: Summary object can add values and compute statistics. 
 
 
 
Given a Summary object 
 
And numbers in the range 0 to 1000 (inclusive) shuffled randomly 
 
When all numbers are added to the Summary object 
 
Then...