Python unittest - assertNotEqual() function

Python unittest – assertNotEqual() function

Last Updated : 29 Aug, 2020

assertNotEqual() in Python is a unittest library function that is used in unit testing to check the inequality of two values. This function will take three parameters as input and return a boolean value depending upon the assert condition. If both input values are unequal assertNotEqual() will return true else return false.

Syntax:

assertNotEqual(firstValue, secondValue, message)

Parameters: assertNotEqual() accept three parameters which are listed below with explanation:

firstValue: variable of any type which is used in the comparison by function
secondValue: variable of any type which is used in the comparison by function
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 TestStringMethods(unittest.TestCase):
    # test function to test equality of two value
    def test_negative(self):
        firstValue = "geeks"
        secondValue = "geeksg"
        # error message in case if test case got failed
        message = "First value and second value are not unequal !"
        # assertNotEqual() to check unequality of first & second value
        self.assertNotEqual(firstValue, secondValue, message)
  
if __name__ == '__main__':
    unittest.main()

Output:

F
======================================================================
FAIL: test_negative (__main__.TestStringMethods)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "p1.py", line 12, in test_negative
    self.assertNotEqual(firstValue, secondValue, message)
AssertionError: 'geeks' == 'geeks' : First value and second value are not unequal!

----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (failures=1)

Example 2: Positive Test case

Python3

# unit test case
import unittest
  
class TestStringMethods(unittest.TestCase):
    # test function to test equality of two value
    def test_positive(self):
        firstValue = "geeks"
        secondValue = "geeks"
        # error message in case if test case got failed
        message = "First value and second value are not unequal !"
        # assertNotEqual() to check equality of first & second value
        self.assertNotEqual(firstValue, secondValue, message)
  
if __name__ == '__main__':
    unittest.main()

Output:

.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

Reference: https://docs.python.org/3/library/unittest.html

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