Now that you understand testing and what it can do for your application, you can create applications that are guaranteed to be less bug-ridden. You will spend less time fixing bugs, and more time adding features that are requested by your users.
As a final challenge to the reader, before moving onto the next chapter, try to get your code coverage over 95%.
In the next chapter, we will finish the book by going over the ways by which you can deploy your application into a production environment on a server.