As the old proverb goes: you cannot build a house without good foundations. The same principle also applies to software engineering. Having a solid test infrastructure in place goes a long way to allowing engineers to work on new features while being confident that their changes will not break the existing code.
Through the course of this chapter, we performed a deep dive into the different types of testing that you need to be aware of when working on medium- to large-scale systems. To begin with, we discussed the concept of unit testing, the essential must-have type of test for all projects, regardless of size, whose primary role is to ensure that individual units of code work as expected in isolation. Then, we tackled more complex patterns, such as integration and functional testing, which verify that units and, by extension, the complete system work harmoniously together...
