Jest is a delightful JavaScript Testing Framework with a focus on simplicity. It is an open-source tool that helps developers write tests for their JavaScript applications. In this section, we will explore the basics of Jest and how it can be used to ensure the quality of your code.

Features of Jest

  • Asynchronous Testing: Jest supports asynchronous tests out of the box.
  • Mocking: Jest provides a comprehensive mocking library that allows you to mock modules and functions.
  • Snapshots: Jest allows you to take snapshots of your application, which can be used to automatically generate test data.
  • Fast: Jest runs tests in parallel and has a very fast test suite execution time.

Getting Started

To get started with Jest, you can follow these steps:

  1. Install Node.js and npm (Node Package Manager).
  2. Create a new project using npm init.
  3. Install Jest by running npm install --save-dev jest.
  4. Create a test file in your project (e.g., app.test.js).
  5. Write your first test and run it using jest.

Example

Here's a simple example to illustrate how to write a test using Jest:

// app.js
function add(a, b) {
  return a + b;
}

// app.test.js
const { add } = require('./app');

test('adds 1 + 2 to equal 3', () => {
  expect(add(1, 2)).toBe(3);
});

To run the test, use the command jest.

Resources

For more information on Jest, you can visit the official documentation.

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