In the previous chapters, we made a lot of progress in gradually creating our application, but how do we know that it actually does what we want it to do? More importantly, how do we know for sure that after six months, or even a year from now, it will still continue to do what we expected it to do at the very beginning? This question is best answered by creating a set of tests, preferably automated, that run a suite of assertions against our code. This ensures that we constantly get the same and expected output given the specific input. Tests give us the much-needed peace of mind that our application not only elegantly is coded and looks beautiful, but that it also performs reliably and is as error-free as possible.
In Chapter 4, Writing Custom Spring Boot Starters, we left off with our web application fitted with a custom-written Spring Boot...