Python unittest – assertEqual() function

assertEqual() in Python is a unittest library function that is used in unit testing to check the equality 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 equal assertEqual() will return true else return false.

Syntax: assertEqual(firstValue, secondValue, message)

Parameters: assertEqual() accept three parameter 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

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

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Output:

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

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

FAILED (failures=1)

Example 2: Positive Test case

Python3

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# 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 equal !"
        # assertEqual() to check equality of first & second value
        self.assertEqual(firstValue, secondValue, message)
  
if __name__ == '__main__':
    unittest.main()

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Output:

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

OK


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

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