Writing an application is only part of the process; it’s also important to check that all of the code works as it should. You can visually inspect the code, but it’s better to execute it in a variety of situations that may arise in the real world to make sure it behaves properly in all situations. This process is called unit testing because the goal is to test the smallest available units of execution.
Typically, the smallest unit is a function or method, many of which combine to form a full application. By breaking it down into individual units, you can minimize how much each test is responsible for. This way, a failure of ...