In this chapter, we are going to test the code we have written in the previous chapters. We will start out with unit tests. We can write unit tests in, and for, JavaScript using Jasmine. After that, we will write UI tests using Selenium. At the end of the chapter, we will have tested our complete application so far and a little bit more.
The obvious advantage to testing your code is that you will be able to catch bugs as soon as they are introduced in any part of the application. How often have you made a change to some page only to find out another page broke because you changed some JavaScript that was shared between the two pages? The more important question: how often did you not find out about the other page breaking? Exactly! So that is why testing your JavaScript can really give you an edge in delivering high-quality software.
A less obvious advantage...