Python assertIn()
Summary: in this tutorial, you’ll learn how to use the Python assertIn() method to test if a member is in a container.
Introduction to the Python assertIn() method
The assertIn() is a method of the TestCase class of the unittest module. The assertIn() method tests if a member is in a container:
assertIn(member, container, msg=None)Code language: Python (python)
If the member is in the container, the test will pass. Otherwise, it’ll fail. The msg is optional. It’ll be displayed in the test result when the test fails.
Internally, the assertIn() method uses the in operator to check:
member in containerCode language: Python (python)
Python assertIn() method examples
The following example uses the assertIn() method to test if a number is in a list and a string is in another string:
import unittestclass TestIn(unittest.TestCase):
def test_in_list(self):
self.assertIn(1, [1, 2, 3])
def test_in_string(self):
self.assertIn('python', 'python tutorial')
Code language: Python (python)
Run the test:
python -m unittest -vCode language: Python (python)
Output:
test_in_list (test_in.TestIn) ... ok
test_in_string (test_in.TestIn) ... ok----------------------------------------------------------------------
Ran 2 tests in 0.001s
OK
Code language: Python (python)
Python assertNotIn() method
The assertNotIn()assertIn() method. The assertNotIn()
assertNotIn(member, container, msg=None)Code language: Python (python)
For example:
import unittestclass TestNotIn(unittest.TestCase):
def test_not_in_list(self):
self.assertNotIn(0, [1, 2, 3])
def test_not_in_string(self):
self.assertNotIn('java', 'python tutorial')
Code language: Python (python)
Run the test:
python -m unittest -vCode language: Python (python)
Output:
test_not_in_list (test_not_in.TestNotIn) ... ok
test_not_in_string (test_not_in.TestNotIn) ... ok----------------------------------------------------------------------
Ran 2 tests in 0.000s
OK
Code language: Python (python)
Summary
- Use the
assertIn()method to test if a member is in a container. - Use the
assertNotIn()method to test if a member is not in a container.