What is Jest?

You know that Facebook guys are never tired of creating new tools. React, redux, react-native and all this reactive family was not enough for them and they created a really powerful, easy-to-use testing framework called Jest: https://facebook.github.io/jest/. Jest is pretty cool because it's self-contained enough for you to not to be distracted by extensive configuration or by looking for asynchronous testing plugins, mocking libraries, or fake timers to use along with your favorite framework. Jest is all in one, although pretty lightweight. Besides that, on every run, it only runs those tests that have been changed since the last test run, which is pretty elegant and nice because it's fast!

Initially created for testing React applications, Jest turned out to be suitable for other purposes, including Vue.js applications.

Check out the great talk given by Roman Kuba during the Vue.js conference in June 2017 in Poland (https://youtu.be/pqp0PsPBO_0), where he explains in a nutshell...