Testing is essential to identify mistakes. Some mistakes might be less important, while some are expensive or could be life-threatening. It is therefore crucial, to test everything that is produced because things can go wrong; humans can make mistakes at any time. Testing is important since it discovers defects/bugs before delivery to the client. It guarantees quality of both the service and software. It makes a software more reliable and easy to use. A thoroughly tested software ensures a reliable and high-performance software operation. In this learning sprint, you will learn how to test JavaScript file using Mocha and Chai testing library.