jest-environment-node

What is jest-environment-node?

The jest-environment-node npm package is a test environment for Jest that simulates a Node.js environment. It is used when testing Node.js specific code. It provides a global environment that's set up for each test file to be executed in a Node-like environment, with all the necessary globals like `process` and `Buffer` available.

What are jest-environment-node's main functionalities?

Simulating Node.js Environment

This configuration in Jest's setup file tells Jest to use the Node environment for testing. It is useful when you want to test code that relies on Node.js APIs.

module.exports = { testEnvironment: 'jest-environment-node' };

Global Setup and Teardown

This feature allows you to extend the Node environment to add custom setup and teardown logic that runs before and after each test suite.

class CustomEnvironment extends NodeEnvironment {
  async setup() {
    await super.setup();
    // Your setup code here
  }

  async teardown() {
    // Your teardown code here
    await super.teardown();
  }
}

Custom Module Mocking

In a Node environment, you can mock Node modules like 'fs' to control their behavior during tests, which is useful for testing code that interacts with the filesystem without actually reading or writing files.

jest.mock('fs', () => ({
  readFileSync: jest.fn().mockReturnValue('mocked content'),
}));

Other packages similar to jest-environment-node

jest-environment-jsdom

This package is similar to jest-environment-node but is intended for testing web applications by simulating a browser environment using jsdom. It provides a DOM API that can be used in tests.

jest-environment-puppeteer

This package integrates Jest with Puppeteer for end-to-end testing. It sets up a browser environment and allows for testing user interactions with a real browser.

jest-environment-webdriver

This package is designed for integration with Selenium WebDriver for browser-based testing. It is similar to jest-environment-puppeteer but uses WebDriver API for controlling browsers.

README

The README file is missing

Changelog

jest 18.0.0

See https://jestjs.io/blog/2016/12/15/2016-in-jest

• The testResultsProcessor function is now required to return the modified results.
• Removed pit and mockImpl. Use it or mockImplementation instead.
• Fixed re-running tests when --bail is used together with --watch.
• pretty-format is now merged into Jest.
• require('v8') now works properly in a test context.
• Jest now clears the entire scrollback in watch mode.
• Added expect.any, expect.anything, expect.objectContaining, expect.arrayContaining, expect.stringMatching.
• Properly resolve snapshotSerializers, setupFiles, transform, testRunner and testResultsProcessor instead of using path.resolve.
• --testResultsProcessor is now exposed through the cli.
• Renamed --jsonOutputFile to --outputFile.
• Added jest-editor-support for vscode and Nuclide integration.
• Fixed test.concurrent unhandled promise rejections.
• The Jest website is now auto-deployed when merging into main.
• Updated testRegex to include test.js and spec.js files.
• Fixes for babel-plugin-jest-hoist when using jest.mock with three arguments.
• The JSON global in jest-environment-node now comes from the vm context instead of the parent context.
• Jest does not print stack traces from babel any longer.
• Fake timers are reset when FakeTimers.useTimers() is called.
• Usage of Jest in watch mode can be hidden through JEST_HIDE_USAGE.
• Added expect.assertions(number) which will ensure that a specified amount of assertions is made in one test.
• Added .toMatchSnapshot(?string) feature to give snapshots a name.
• Escape regex in snapshots.
• jest-react-native was deprecated and now forwards react-native.
• Added .toMatchObject matcher.
• Further improve printing of large objects.
• Fixed NaN% Failed in the OS notification when using --notify.
• The first test run without cached timings will now use separate processes instead of running in band.
• Added .toHaveProperty matcher.
• Fixed Map/Set comparisons.
• test.concurrent now works with --testNamePattern.