Infinite Jest
Unit Testing with the Jest Framework
- Greg Douglas
What is Jest?
- A unit testing framework
- Developed by Facebook
- Originally based on Jasmine
- Similar syntax to Jasmine/Mocha
Why use Jest?
- It is FAST
- Configuration is easy
- It has a great CLI and watch mode
- Clear and concise error messages
- Supports ES6 natively
- Built with React in mind
Walkthrough
Comparison to Chai Expect
const { expect } = require('chai');
describe('foo', function() {
it('should do things', function() {
const foo = 'bar';
expect(foo).to.be.a('string');
expect(foo).to.equal('bar');
expect(foo).to.have.lengthOf(3);
expect(foo).not.to.be.null;
});
});
/* expect available globally */
describe('foo', () => {
it('should do things', () => {
const foo = 'bar';
expect(typeof foo).toBe('string');
expect(foo).toEqual('bar');
expect(foo).toHaveLength(3);
expect(foo).not.toBeNull();
});
});