Writing and executing test cases

In this recipe, we will learn how to define and run tests using the pytest library.

Getting ready

We will use the pytest module. We should install the module, adding it to our requirements.txt file as follows:

$ echo "pytest==5.4.1" >> requirements.txt
$ pip install -r requirements.txt

We will use the file test_case.py. You can download it from the GitHub repository at https://github.com/PacktPublishing/Python-Automation-Cookbook-Second-Edition/tree/master/Chapter12/tests.

How to do it...

1. Check the file tests/test_case.py, which contains the definition of four tests:

   LIST = [1, 2, 3]
   def test_one():
       # Nothing happens
       pass
   def test_two():
       assert 2 == 1 + 1
   def test_three():
       assert 3 in LIST
   def test_fail():
       assert 4 in LIST
   

2. Run pytest to run the test file:

   $ pytest tests/test_case.py
   =====================.  test session starts ======================
   platform...