Unit Testing with ts-jest
Large systems require constant testing to ensure they are correct. This is where unit testing comes in. Some of the biggest software projects in the world have hundreds of millions of lines of code and thousands of features and views. It's simply not possible to manually test every feature. This is where unit tests come in. Unit tests test the smallest unit of code, often a single statement or function, and give us quick feedback if we've done something to change the behavior of an application. Short feedback cycles are a developer's best friend and unit tests are one of the most powerful tools to achieve them.
There are many testing frameworks that can help us to unit test our code. Jest is a popular testing framework from Facebook. You may also come across other frameworks, such as Jasmine, Mocha, or Ava. Jest is a "batteries included" framework that will seem familiar to users of those other frameworks as it has tried to incorporate...