example of patch and how it can alter functions for use in tests

my_module.py

from my_other_module import function_4

def function_1():
    return 1

def function_2():
    return_tuple = (function_1(), function_3(), function_4())
    return return_tuple

def function_3():
    return 3

my_other_module.py

def function_4():
    return 4

test.py

import unittest
import os
from unittest.mock import patch
import my_module

def simple_urandom(length):
    return 'f' * length

class TestRandom(unittest.TestCase):
    @patch('os.urandom', side_effect=simple_urandom)
    def test_urandom(self, urandom_function):
        print(os.urandom(5))
        assert os.urandom(5) == 'fffff'

    @patch('my_module.function_1', return_value=2)
    @patch('my_module.function_3', return_value=2)
    @patch('my_module.function_4', return_value=2)
    def test_method_1(self, *args):
        assert my_module.function_2() == (2, 2, 2)

if __name__ == '__main__':
    unittest.main()