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

29.5.0

Features

[jest-changed-files] Support Sapling (#13941)
[jest-circus, @jest/cli, jest-config] Add feature to randomize order of tests via CLI flag or through the config file(#12922)
[jest-cli, jest-config, @jest/core, jest-haste-map, @jest/reporters, jest-runner, jest-runtime, @jest/types] Add workerThreads configuration option to allow using worker threads for parallelization (#13939)
[jest-cli] Export yargsOptions (#13970)
[jest-config] Add openHandlesTimeout option to configure possible open handles warning. (#13875)
[@jest/create-cache-key-function] Allow passing length argument to createCacheKey() function and set its default value to 16 on Windows (#13827)
[jest-message-util] Add support for AggregateError (#13946 & #13947)
[jest-message-util] Add support for Error causes in test and it (#13935 & #13966)
[jest-reporters] Add summaryThreshold option to summary reporter to allow overriding the internal threshold that is used to print the summary of all failed tests when the number of test suites surpasses it (#13895)
[jest-runtime] Expose @sinonjs/fake-timers async APIs functions advanceTimersByTimeAsync(msToRun) (tickAsync(msToRun)), advanceTimersToNextTimerAsync(steps) (nextAsync), runAllTimersAsync (runAllAsync), and runOnlyPendingTimersAsync (runToLastAsync) (#13981)
[jest-runtime, @jest/transform] Allow V8 coverage provider to collect coverage from files which were not loaded explicitly (#13974)
[jest-snapshot] Add support to cts and mts TypeScript files to inline snapshots (#13975)
[jest-worker] Add start method to worker farms (#13937)
[jest-worker] Support passing a URL as path to worker (#13982)

Fixes

[babel-plugin-jest-hoist] Fix unwanted hoisting of nested jest usages (#13952)
[jest-circus] Send test case results for todo tests (#13915)
[jest-circus] Update message printed on test timeout (#13830)
[jest-circus] Avoid creating the word "testfalse" when takesDoneCallback is false in the message printed on test timeout AND updated timeouts test (#13954)
[jest-environment-jsdom] Stop setting document to null on teardown (#13972)
[@jest/expect-utils] Update toStrictEqual() to be able to check jest.fn().mock.calls (#13960)
[@jest/test-result] Allow TestResultsProcessor type to return a Promise (#13950)

Chore & Maintenance

[jest-snapshot] Remove dependency on jest-haste-map (#13977)

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 06 Mar 2023

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