@lightspeed/config-jest

Introduction

Jest dependencies and configuration for both JavaScript and TypeScript in a convenient package.

Important note

This configuration is meant for Babel+TypeScript projects only, which is our default setup for Lightspeed web applications. For pure TypeScript projects, please use ts-jest directly instead.

Quick Start

Install

Install the dependencies (@types/jest is only needed if your project uses TypeScript):

yarn add -D @lightspeed/config-jest jest @types/jest

Setup

Consume the Jest configuration by creating a jest.config.js file:

// jest.config.js
module.exports = require('@lightspeed/config-jest');

Optionally, extend the configuration as you see fit:

// jest.config.js
const baseConfig = require('@lightspeed/config-jest');

module.exports = Object.assign(baseConfig, {
  testPathIgnorePatterns: ['<rootDir>/some-dir'],
});

You can also add your own jest.setup.js file with setupFilesAfterEnv:

// jest.config.js
const baseConfig = require('@lightspeed/config-jest');

module.exports = Object.assign(baseConfig, {
  setupFilesAfterEnv: ['<rootDir>/jest.setup.js'],
});

React projects

If in a React project, we highly recommend installing @testing-library/react and @testing-library/jest-dom as they are amazing testing tools on top of Jest for React.
Install dependencies:

yarn add -D @testing-library/react @testing-library/jest-dom

Then, in your jest.setup.js file, add:

// add some helpful assertions
require('@testing-library/jest-dom/extend-expect');

Note that react-testing-library methods will be available out of the box after installing the library

Node projects

For node-only projects, you must set testEnvironment to node instead of the default jsdom:

// jest.config.js
const baseConfig = require('@lightspeed/config-jest');

module.exports = Object.assign(baseConfig, {
  testEnvironment: 'node',
});

Add an npm script to run your tests

Finally, add an npm script to run jest:

{
  "scripts": {
    "test": "jest"
  }
}

By default jest will run tests on any file named with *.test.(js|jsx|ts|tsx).
Go forth and test away! 🎉