Python Monkey Patching

Monkey Patching:

• Monkey Patching refers to dynamic (run-time) modifications of a class or module
• A MonkeyPatch is a piece of Python code which extends or modifies other code at runtime
• The unittest.mock library makes use of monkey patching to replace part of your code under test by mock objects. 
• It provides functionality for writing clever unittests

### test1.py 

class A: 

    def func(self): 

        print("func() is being called")

### test2.py

from test1 import A

def monkey_func(self): 

     print("monkey_func() is being called...")

   

# Replacing address of "func" with "monkey_func" 

A.func = monkey_func

if __name__ == '__main__':

    obj = A()

  

    # calling function "func" whose address got replaced with "monkey_func()" 

    obj.func() 

Output:

monkey_func() is being called...