Chai is a test-assertion library that supports test-driven development (TDD) and behavior-driven development (BDD) test styles. The main goal of Chai is to reduce the amount of work necessary to create a test assertion and make the test more readable. We can install Chai using the following command:
npm install --save-dev chai @types/chai
Please note that we are going to learn more about TDD and BDD later in this chapter in the section titled Testing methodologies.
