Mastering React Test-Driven Development

Writing a failing test

What exactly is a test? We'll discover that by writing one. In your project directory, type the following commands:

mkdir testtouch test/Appointment.test.js

Open the test/Appointment.test.js file in your favorite editor or IDE and enter the following:

describe('Appointment', () => {});

The describe function defines a test suite, which is simply a set of tests with a given name. The first argument is the name (or description) of the unit you are testing. It could be a React component, a function, or a module. The second argument is a function inside of which you define your tests.

All of the Jest functions are already required and available in the global namespace when you run the npm test command. You don't need to ...