In the last exercise, we saw how to check for equality between two values in the unittest framework using the .assertEqual method of the TestCase class. The framework relies on built-in assert methods instead of assert statements to track results without actually raising any exceptions. Specific assert methods take arguments instead of a condition, and like assert statements, they can take an optional message argument.
Let’s go over three commonly used assert methods for testing equality and membership, their general syntax, and their assert statement equivalents.
assertEqual: The
assertEqual()method takes two values as arguments and checks that they are equal. If they are not, the test fails.self.assertEqual(value1, value2)assertIn: The
assertIn()method takes two arguments. It checks that the first argument is found in the second argument, which should be a container. If it is not found in the container, the test fails.self.assertIn(value, container)assertTrue: The
assertTrue()method takes a single argument and checks that the argument evaluates toTrue. If it does not evaluate toTrue, the test fails.self.assertTrue(value)
The equivalent assert statements would be the following:
| Method | Equivalent |
|---|---|
self.assertEqual(2, 5) |
assert 2 == 5 |
self.assertIn(5, [1, 2, 3]) |
assert 5 in [1, 2, 3] |
self.assertTrue(0) |
assert bool(0) is True |
The full list for equality and membership can be seen in the Python documentation. Let’s put these methods into practice!
Instructions
Small World Air planes are equipped with an on-board entertainment system which we need to create some tests for. Take some time to review entertainment.py and tests.py.
Note the three functions in entertainment.py:
get_daily_movie(): returns the movie of the day.get_licensed_movies(): returns a list of licensed movies the plane can play.get_wifi_status(): returns the current wifi status of the plane.
Note the two test cases in tests.py:
test_movie_license(): is intended to test if a daily movie is licensedtest_wifi_status(): is intended to test if the wifi is currently active
Run the code to proceed.
Every flight has a free movie. We want to create a test that checks our database to make sure that the uploaded movie has a valid license, or else we could pay some hefty fines.
Inside of our test_movie_license() test method, we have two variables defined:
daily_movie: which stores the value of the current free daily movie.licensed_movies: which stores the value of all the current licensed movies.
To test if we have a license for the current daily movie, we need to compare if daily_movie exists inside of licensed_movies.
Use the self.assertIn() assert method inside of test_movie_license() to check if the daily_movie is licensed.
Our entertainment system also provides WiFi as a purchase option for passengers. We want to make a test that ensures the WiFi is enabled.
Inside the test method called test_wifi_status() we have a variable called wifi_enabled which stores the boolean value of whether the wifi is turned on or not.
Use the self.assertTrue() assert method inside of test_wifi_status() to test that wifi_enabled is True. The test should fail because currently wifi is disabled.