Everybody knows how important testing is and yet many of us have projects without tests, commented out tests, or testing disabled. In a perfect world, we build our new project with tests and everything is great until we get asked to refactor the application and now have hundreds of broken tests. In addition, I may have implemented my project with NgRx and I have a whole new set of items to test; actions, reducers, and effects. Jest.js makes testing regular and NgRx projects a breeze. I'll show you how to install and start testing with Jest.js with zero configuration. We will dive into serializers to simplify the output and explore how to test simple functions as well as actions, reducers, and effects. I'll show you how easy it is to test your components and know that they will render exactly the way you expect. I'll also be showing you how your refactor with hundreds of broken tests can be fixed in a matter of minutes.