Python unittest – assertIsNone() function
assertIsNone() in Python is a unittest library function that is used in unit testing to check that input value is None or not. This function will take two parameters as input and return a boolean value depending upon assert condition. If input value is equal to None assertIsNone() will return true else return false.
Syntax: assertIsNone(testValue, message)
Parameters: assertIsNone() accept two parameters which are listed below with explanation:
- testValue: test variable as the input value to check equality with None
- message: a string sentence as a message which got displayed when the test case got failed.
Listed below are two different examples illustrating the positive and negative test case for given assert function:
Example 1: Negative Test case
Python3
# unit test case import unittest class TestMethods(unittest.TestCase): # test function def test_negative(self): firstValue = "zambiatek" # error message in case if test case got failed message = "Test value is not none." # assertIsNone() to check that if input value is none self.assertIsNone(firstValue, message) if __name__ == '__main__': unittest.main() |
Output:
F
======================================================================
FAIL: test_negative (__main__.TestMethods)
----------------------------------------------------------------------
Traceback (most recent call last):
File "p1.py", line 14, in test_negative
self.assertIsNone(firstValue, message)
AssertionError: 'zambiatek' is not None : Test value is not none.
----------------------------------------------------------------------
Ran 1 test in 0.000s
FAILED (failures=1)
Example 2: Positive Test case
Python3
# unit test case import unittest class TestMethods(unittest.TestCase): # test function def test_positive(self): firstValue = None # error message in case if test case got failed message = "Test value is not none." # assertIsNone() to check that if input value is none self.assertIsNone(firstValue, message) if __name__ == '__main__': unittest.main() |
Output:
. ---------------------------------------------------------------------- Ran 1 test in 0.000s OK
Reference: https://docs.python.org/3/library/unittest.html
