9.1. Unit Testing

Manual testing is like integration testing, making sure that your application works from a high level. Unit testing is much more low level, ensuring that particular pieces of code behind the scenes are performing as expected. Unit testing is much more likely to reveal cross-browser issues, but it allows you to resolve them quickly, because you need to examine only small sections of code.

The other advantage to unit testing is that it paves the way for automation. We’ll cover this in more detail later in this chapter, but unit tests make it possible to set up a continuous integration server, running the application’s tests every time the code is committed. This is much quicker than running through your whole application manually, and making sure that changes to one piece of code aren’t having any side effects elsewhere in the application.