jest-config

What is jest-config?

The jest-config package is used for configuring Jest, a popular JavaScript testing framework. It allows developers to programmatically access and manipulate Jest's configuration settings, making it easier to set up and customize tests for JavaScript projects. This package is particularly useful for complex setups or when integrating Jest into larger, automated workflows.

What are jest-config's main functionalities?

Accessing Default Configuration

This feature allows developers to access Jest's default configuration settings. It's useful for understanding the baseline configuration and for extending or customizing these defaults in a project.

const { defaults } = require('jest-config');
console.log(defaults);

Generating a Custom Configuration

This feature enables the creation of a custom Jest configuration programmatically. It's particularly useful for dynamically generating configurations based on specific project requirements or environments.

const { makeConfig } = require('jest-config');
const customConfig = makeConfig({
  rootDir: process.cwd(),
  transform: {
    '^.+\\.js$': 'babel-jest'
  }
});
console.log(customConfig);

Other packages similar to jest-config

mocha

Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple. While Mocha itself is not a configuration tool, it offers a flexible API and a variety of command-line options for configuring tests, similar to how jest-config allows for Jest test configuration.

karma

Karma is a test runner for JavaScript that runs on Node.js. It is designed to work with any testing framework, such as Jasmine, Mocha, or QUnit. Karma itself is more about running tests in different environments rather than configuring a specific testing framework. However, it deals with the aspect of setting up testing environments, which can be seen as a parallel to configuring testing frameworks with jest-config.

ava

AVA is a test runner for Node.js with a concise API, detailed error output, and process isolation that lets you develop with confidence. AVA's configuration approach is more direct and less flexible compared to jest-config, focusing on simplicity and convention over configuration.

README

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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.