Have you ever worked on a huge system consisting of a plethora of objects which
are in turn dependent on other complex objects? Been stuck at the unit testing
phase of your module due to the inescapable dependencies? Mock Testing provides you the ability to isolate and test your code without any interference of the dependencies and other variables like network issues and traffic fluctuations.
In simple words, in mock testing, we replace the dependent objects with mock objects. These mock objects simulate or ‘mock’ the behavior of real objects and exhibit the exact characteristics of the authentic ones. The main goal of mock testing is to centralize the focus on the testing without being concerned about the dependencies.
Let’s take an example- You have a web service that makes a POST request to
update or store new entries in the API server every time you hit submit on a form.
We do not need to store unnecessary test data in the server each time we run a
test. Mock testing allows the user to replace the service with a mock object to validate the functionality without storing redundant information.
Benefits of Mock Tests
The main advantages of Mock Tests are Isolation, Development and Test Speed, and more efficient Load Testing. Let’s take a closer look at these benefits.
The advantage of mock object usage is that you can easily isolate the dependencies which allows you to manage the test in a limiting span. This way if a test fails you can know that it’s not due to the mocked object but the unit code. For shorter and more focused tests, you should maintain a limiting scope. Mocking requires setting up extra arrangements to set the mockup objects. However, the fewer dependencies you have, the easier your test will be to understand and manage in a smaller scope.
- Development and Test Speed
Mocking enables you to pinpoint the source of the failure more easily. As a result it speeds up the tests. The speed of running unit tests plays a vital role in software development. The slower the test runs, the higher the percentage of losing interest in running tests since the developers won’t get the benefit immediately. Mock tests overcome time constraints through the use of mock databases, file system operations, and external services. Isolating failures also speeds up development. You can already start the test since there is no need to wait for another team to wait for the development of the mocked object/dependency to be complete. This way you can develop all the units of the project in parallel.
- More efficient load testing
When testing a single user per test, it’s often OK to use a third-party API for testing code with side effects such as sending SMS or making an eCommerce billing transaction. However, when running thousands of simultaneous users, it’s much more important to mock these dependencies. With mock testing, there is no abuse for third-party services or unnecessary side effects.