Jest comes pre-packaged with the ability to track code coverage for the modules you're testing, but it takes a little extra work to make it track untested files as well. Let's look at what Jest can do for you, what you have to do yourself, and how to setup code coverage thresholds so you can work to improving the code coverage numbers for your projects.
Often when testing, you use the actual result to create your assertion and have to manually update it as you make changes to the feature. With Jest snapshot testing, you can let Jest do this part for you and write more tests and features faster and with more confidence. Let's learn about how you can use Jest snapshot testing to improve your own workflow.
In this lesson, we'll write a brand new function called
arrayify using the Test Driven Development workflow of red-green-refactor. Test Driven Development (aka TDD) is great because it helps you focus on one task at a time and when you're all finished, you can refactor or add features with confidence because the test suite acts as a safety net. In this lesson we're using the amazing Jest testing framework.