Up until this point, we've been pretty much flying by the seat of our pants when it comes to the code we've been writing! We've literally had no way of knowing whether the code worked until we tested it out in an actual browser.
In this chapter, we will cover the following topics:
Running tests with the Mocha test framework
Writing tests with the Chai assertion library
Spies and stubs with Sinon and Proxyquire
Writing your first test
Testing our application
Tests are great for making sure your code functions properly, but they're also awesome for preventing new unexpected bugs from suddenly popping up because of an innocent little change you made to some unsuspecting code.