What is Jest?

Jest is a test runner. This means that it runs the tests you have written and tells you if the code passes or fails those tests.

It's created by the team at Facebook

It comes pre-installed in every create-react-app application

Works with many front-end frameworks including React, Vue and many more

Why is it useful?

Provides an overview of your code coverage - this means you know how much of your code is covered by tests. Generally, the higher this number, the better.

What can we test with Jest?

We can do things like check that our app renders correctly and doesn't crash when it loads.