What if our Logic goes Wrong?

Below code, uses doctests to validate the factorial function. The function is designed to recursively compute the factorial of a positive integer, as documented in the docstring. However, there’s an issue with the recursive logic. The testmod function is called to verify the function’s correctness against the provided test cases.

Python3

# import testmod for testing our function 
from doctest import testmod 
  
# define a function to test 
def factorial(n): 
    ''' 
    This function calculates recursively and 
    returns the factorial of a positive number. 
    Define input and expected output: 
    >>> factorial(3) 
    6 
    >>> factorial(5) 
    120 
    '''
    if n <= 1: 
        return 1
    # wrong logic for factorial 
    return factorial(n - 1) 
  
# call the testmod function 
if __name__ == '__main__': 
    testmod(name ='factorial', verbose = True)

Output:

Trying:
    factorial(3)
Expecting:
    6
**********************************************************************
File "woking_with_csv.py", line 33, in factorial.factorial
Failed example:
    factorial(3)
Expected:
    6
Got:
    1
Trying:
    factorial(5)
Expecting:
    120
**********************************************************************
File "woking_with_csv.py", line 35, in factorial.factorial
Failed example:
    factorial(5)
Expected:
    120
Got:
    1
1 items had no tests:
    factorial
**********************************************************************
1 items had failures:
   2 of   2 in factorial.factorial
2 tests in 2 items.
0 passed and 2 failed.
***Test Failed*** 2 failures.

Note: If ‘verbose’ is set to False(default), output will be shown in case of failure only, not in the case of success.

Testing in Python using Doctest module

Docstrings in Python are used not only for the description of a class or a function to provide a better understanding of the code and use but, also used for Testing purposes. Testing is a critical aspect of software development that ensures code functions as expected and guards against bugs. In Python, the Doctest module provides a simple yet powerful way to test code by embedding test cases within docstrings.

Table of Content

What is Doctest Module in Python
Why Choose Doctest in Python?
How to Use Doctest in Python?
What if our Logic goes Wrong?
Examples to Understand Doctest Module
Limitations of Doctest module
Frequently Asked Questions (FAQ’s)

What if our Logic goes Wrong?

Testing in Python using Doctest module

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