The @jest/types package provides TypeScript definitions and utility types for Jest, a popular JavaScript testing framework. It includes types for Jest configuration, global variables, and other utilities that help in creating type-safe test environments and extending Jest functionalities.

What are @jest/types's main functionalities?

Config

Defines types for Jest configuration options. This allows for type-safe Jest configuration files, ensuring that any configuration options passed to Jest are valid.

{"globals": {"myGlobal": "value"}, "testMatch": ["**/__tests__/**/*.js?(x)", "**/?(*.)+(spec|test).js?(x)"]}

Global

Provides types for Jest's global variables and functions, such as 'describe', 'it', and 'expect'. This is useful for creating custom global setups or mocks in a type-safe manner.

"declare var jest: jest.Jest"

Mock

Includes types for Jest's mocking utilities, enabling developers to create and manipulate mocks with full TypeScript support.

"const mockedFunction: jest.Mock = jest.fn()"

Other packages similar to @jest/types

Changelog

Source

28.1.1

Features

[jest] Expose Config type (#12848)
[@jest/reporters] Improve GitHubActionsReporters annotation format (#12826)
[@jest/types] Infer argument types passed to test and describe callback functions from each tables (#12885, #12905)

Fixes

[@jest/expect-utils] Fix deep equality of ImmutableJS OrderedMaps (#12899)
[jest-docblock] Handle multiline comments in parseWithComments (#12845)
[jest-mock] Improve spyOn error messages (#12901)
[jest-runtime] Correctly report V8 coverage with resetModules: true (#12912)
[jest-worker] Make JestWorkerFarm helper type to include methods of worker module that take more than one argument (#12839)

Chore & Maintenance

[docs] Updated docs to indicate that jest-environment-jsdom is a separate package #12828
[docs] Document the comments used by coverage providers #12835
[docs] Use docusaurus-remark-plugin-tab-blocks to format tabs with code examples (#12859)
[jest-haste-map] Bump walker version (#12324)

Readme

Source

@jest/types

This package contains shared types of Jest's packages.

If you are looking for types of Jest globals, you can import them from @jest/globals package:

import {describe, expect, it} from '@jest/globals';

describe('my tests', () => {
  it('works', () => {
    expect(1).toBe(1);
  });
});

If you prefer to omit imports, a similar result can be achieved installing the @types/jest package. Note that this is a third party library maintained at DefinitelyTyped and may not cover the latest Jest features.

Another use-case for @types/jest is a typed Jest config as those types are not provided by Jest out of the box:

// jest.config.ts
import {Config} from '@jest/types';

const config: Config.InitialOptions = {
  // some typed config
};

export default config;

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Last updated on 07 Jun 2022

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