Design Principles and Unit Testing

In this lesson, we are first going to take a look at unit testing from a conceptual point of view. We will revisit some of the software engineering principles we discussed in the previous chapter to get an idea of how this is related to clean code.

After that, we will discuss in more detail how to put these concepts into practice (at the code level), and what frameworks and tools we can make use of.

What unit tests are

First, we quickly define what unit testing is about. Unit tests are code in charge of validating other parts of the code. Normally, anyone would be tempted to say that unit tests validate the "core" of the application, but such a definition regards unit tests as secondary, which is not the way they are thought of in this course. Unit tests are core and a critical component of the software, and they should be treated with the same considerations as the business logic.