assertIn() in Python is a unittest library function that is used in unit testing to check whether a string is contained in other or not. This function will take three string parameters as input and return a boolean value depending upon the assert condition. If the key is contained in container string it will return true else it returns false.
Syntax: assertIn(key, container, message)
Parameters: assertIn() accept three parameters which are listed below with explanation:
- key: a string whose presence is checked in the given container
- container: a string in which key string is searched
- 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
# test suiteimport unittest class TestStringMethods(unittest.TestCase): # test function to test whether key is present in container def test_negative(self): key = "gfg" container = "neveropen" # error message in case if test case got failed message = "key is not in container." # assertIn() to check if key is in container self.assertIn(key, container, message) if __name__ == '__main__': unittest.main() |
Output:
F
======================================================================
FAIL: test_negative (__main__.TestStringMethods)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/e920f2cd9195a3fd72bd531f7f101754.py", line 12, in test_negative
self.assertIn(key, container, message)
AssertionError: 'gfg' not found in 'neveropen' : key is not in container.
----------------------------------------------------------------------
Ran 1 test in 0.001s
FAILED (failures=1)
Example 2: Positive Test case
Python3
# test suiteimport unittest class TestStringMethods(unittest.TestCase): # test function to test whether key is present in container def test_positive(self): key = "Lazyroar" container = "neveropen" # error message in case if test case got failed message = "key is not in container." # assertIn() to check if key is in container self.assertIn(key, container, message) if __name__ == '__main__': unittest.main() |
Output:
. ---------------------------------------------------------------------- Ran 1 test in 0.000s OK
Reference: https://docs.python.org/3/library/unittest.html
