For today’s blog I will be discussing the topic of testing with mocking. I recently read an article called “Mock? What, When, How?” by Lovis Moller. So let’s jump right in. What is mocking in terms of testing? Think about your code as a giant puzzle. All the pieces fit together, but they fit together in specific ways. Say you’re missing a piece of the puzzle because your partner hasn’t finished their part of the code yet. The new problem is this: how can I test my code without my partner’s piece of the puzzle? The answer is by using mocking. Mocking allows us to emulate or “mock” our partner’s puzzle piece that we are missing so that we can test our code without having to actually have the rest of the puzzle pieces. So mocking seems like a pretty good idea and like something we should use all the time, right? Wrong. The article talks about some of the pitfalls of mocking, which we will now talk about. First, the article says to mock only code you own. Do not mock third-party code simply because it’s not yours and you do not know how it works or how it should work. Another rule of thumb is to avoid mocking values and concrete classes. You should avoid mocking values because the objective of mocking is not to test for specific values, but rather it is meant to test the relationships and interactions between different classes (pieces of the puzzle). Concrete classes should not be mocked because of all the extras (methods, unused lines of code, etc) that come along with the concrete class. It is more efficient to use mocking with an interface in this case.
In the past few weeks we have been doing testing with mocking in our CS class. I think it is a really neat and useful way to test because you can get stuff done on your end without having to wait for someone else to finish. In a world where we work as groups to complete projects, human error is always an issue. We could have our parts of the code done weeks before a deadline while our partner waits until the night before the deadline. Problem here is that we might not be able to proceed in testing and fixing our code because what our code does as a function relies on our partners code. We certainly do not want to wait until the night before a deadline to test and fix everything. Mocking helps us with this by emulating the code we are dependent on. I hope to use this more in the future.
Here’s the link to the blog: https://blog.codecentric.de/en/2018/03/mock-what-when-how/
From the blog CS@Worcester – The Average CS Student by Nathan Posterro and used with permission of the author. All other rights reserved by the author.