@jest/types

What is @jest/types?

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

@types/jest

Before Jest provided its own TypeScript definitions, @types/jest was the go-to package for Jest types. It serves a similar purpose by providing type definitions for Jest, but @jest/types is more up-to-date and maintained by the Jest team.

ts-jest

While ts-jest is primarily a TypeScript preprocessor for Jest, allowing Jest to understand TypeScript files, it also includes some utility types for configuration. However, @jest/types focuses solely on providing comprehensive type definitions for Jest's API.

jest-mock-extended

jest-mock-extended provides extended types and utilities for mocking in Jest, particularly with TypeScript. It complements @jest/types by offering more detailed mock creation and manipulation capabilities, though @jest/types provides the foundational type definitions.

README

The README file is missing

Changelog

25.5.0

Features

• [@jest/globals] New package so Jest's globals can be explicitly imported (#9801)
• [jest-core] Show coverage of sources related to tests in changed files (#9769)
• [jest-runtime] Populate require.cache (#9841)

Fixes

• [*] Use graceful-fs directly in every package instead of relying on fs being monkey patched (#9443)
• [expect] Prints the Symbol name into the error message with a custom asymmetric matcher (#9888)
• [jest-circus, jest-jasmine2] Support older version of jest-runtime (#9903 & #9842)
• [@jest/environment] Make sure not to reference Jest types (#9875)
• [jest-message-util] Code frame printing should respect --noStackTrace flag (#9866)
• [jest-runtime] Support importing CJS from ESM using import statements (#9850)
• [jest-runtime] Support importing parallel dynamic imports (#9858)
• [jest-transform] Improve source map handling when instrumenting transformed code (#9811)

Chore & Maintenance

• [docs] Add an example for mocking non-default export class

Performance

• [jest-resolve] Update resolve to a version using native realpath, which is faster than the default JS implementation (#9872)
• [jest-resolve] Pass custom cached realpath function to resolve (#9873)
• [jest-runtime] Add teardown method to clear any caches when tests complete (#9906)
• [jest-runtime] Do not pass files required internally through transformation when loading them (#9900)
• [jest-runtime] Use Maps instead of object literals as cache holders (#9901)