Mock for tests

Key 1: Mock what you do not have.

When we are using test driven development, we have to write test cases for the components that rely on other components that are not written yet or take a lot of time to execute. This is close to impossible until we create mocks and stubs. In this scenario, stubs or mocks are very useful. We use a fake object instead of a real one to write the test case. This can be made very easy if we use tools that are provided by the language. For example, in the following code, we only have the interface for the worker class, and no real implementation of it. We want to test the assign_if_free function.

Instead of writing any stub ourselves, we use the create_autospec function to create a mock object from the definition of the Worker abstract class. We also set up a return value for the function call of checking whether worker was busy or not:

import six
import unittest
import sys
import abc
if sys.version_info[0:2] >= (3, 3):
    from unittest.mock...