jestjs/jest

Delightful JavaScript Testing.

🃏 Delightful JavaScript Testing **👩🏻‍💻 Developer Ready**: A comprehensive JavaScript testing solution. Works out of the box for most JavaScript projects. **🏃🏽 Instant Feedback**: Fast, interactive watch mode only runs test files related to changed files. **📸 Snapshot Testing**: Capture snapshots of large objects to simplify testing and to analyze how they change over time. See more on jestjs.io ## Table of Contents - [Getting Started](#getting-started) - [Running from command line](#running-from-command-line) - [Additional Configuration](#additional-configuration) - [Generate a basic configuration file](#generate-a-basic-configuration-file) - [Using Babel](#using-babel) - [Using webpack](#using-webpack) - [Using Vite](#using-vite) - [Using Parcel](#using-parcel) - [Using Typescript](#using-typescript) - [Documentation](#documentation) - [Badge](#badge) - [Contributing](#contributing) - [Code of Conduct](#code-of-conduct) - [Contributing Guide](#contributing-guide) - [Good First Issues](#good-first-issues) - [Credits](#credits) - [Backers](#backers) - [Sponsors](#sponsors) - [License](#license) - [Copyright](#copyright) ## Getting Started Install Jest using [`yarn`](https://yarnpkg.com/en/package/jest): ```bash yarn add --dev jest ``` Or [`npm`](https://www.npmjs.com/package/jest): ```bash npm install --save-dev jest ``` Note: Jest documentation uses `yarn` commands, but `npm` will also work. You can compare `yarn` and `npm` commands in the [yarn docs, here](https://yarnpkg.com/en/docs/migrating-from-npm#toc-cli-commands-comparison). Let's get started by writing a test for a hypothetical function that adds two numbers. First, create a `sum.js` file: ```javascript function sum(a, b) { return a + b; } module.exports = sum; ``` T