unittest.TestCase Lifecycle

Sometimes, when doing tests, we might need to do something:

• before/after all tests or
• before/after each test

This concept is almost universal and it is implemented similarly in certain test frameworks such as JUnit (in Java) or unittest (in Python) - this later, the one we want to explore.

In our example we will build a base test class - called SampleTestCase - that will implement the main life-cycle methods of a TestCase.

class SampleTestCase(TestCase):  
  
    @classmethod  
    def setUpClass(cls) -> None:  
        print("setUpClass")  
  
    def setUp(self) -> None:  
        print("setUp")  
  
    def tearDown(self) -> None:  
        print("tearDown")  
  
    @classmethod  
    def tearDownClass(cls) -> None:  
        print("tearDownClass")

Looking to SampleTestCase code, we see four methods:

• setUpClass and tearDownClass will run before and after all the test cases are run (respectively)
• setup and tearDown will run before and after each test case is run (respectively)

If we had a test case like this:

class ConcreteImplementationOfTestCase(SampleTestCase):  
  
    def test_do_return_equal_when_true_equals_1(self):  
        self.assertEqual(True, 1)  
  
    def test_do_return_equal_when_true_equals_0(self):  
        self.assertEqual(False, 0)

The output would be the following

$ python -m unittest test_unnittest_lifecycle_methods.py
setUpClass
setUp
tearDown
.setUp
tearDown
.tearDownClass

Simple, and very powerful!