jest-util

What is jest-util?

The jest-util package provides utility functions for Jest, a popular JavaScript testing framework. It includes a variety of helpers and tools that are used internally by Jest but can also be useful for developers working with or extending Jest tests.

What are jest-util's main functionalities?

Console Replacement

This feature allows for the creation of a custom console that buffers all logs. This is useful for controlling and testing console output during test runs.

const { BufferedConsole } = require('jest-util');
const customConsole = new BufferedConsole();
customConsole.log('Hello, this is a buffered log.');

Error Formatting

This function formats execution errors for display in Jest's output, providing a standardized view of test errors, including stack traces.

const { formatExecError } = require('jest-util');
const error = new Error('Test error');
const config = {rootDir: '/path/to/project', testMatch: []};
console.log(formatExecError(error, config, {noStackTrace: false}, undefined, true));

Test Path Normalization

This utility normalizes file paths for glob matching, which is particularly useful on Windows where path separators differ.

const { replacePathSepForGlob } = require('jest-util');
const path = 'path\to\test\file.js';
console.log(replacePathSepForGlob(path));

Other packages similar to jest-util

chai

Chai is an assertion library similar to jest-util in that it is used to help with testing JavaScript applications. Unlike jest-util, Chai focuses more on providing a rich set of assertions rather than utilities for managing Jest environments or outputs.

mocha

Mocha is a test framework that, like Jest, can utilize utility packages for enhanced testing capabilities. While jest-util specifically supports Jest, Mocha has its own set of utilities and plugins that serve a similar purpose but are tailored to Mocha's ecosystem.

sinon

Sinon provides standalone test spies, stubs, and mocks for JavaScript. It complements jest-util by offering more focused functionalities for creating and managing test doubles, which can be used alongside or independently of Jest.

README

The README file is missing

Changelog

29.1.0

Features

• [expect, @jest/expect] Support type inference for function parameters in CalledWith assertions (#13268)
• [expect, @jest/expect] Infer type of *ReturnedWith matchers argument (#13278)
• [@jest/environment, jest-runtime] Allow jest.requireActual and jest.requireMock to take a type argument (#13253)
• [@jest/environment] Allow jest.mock and jest.doMock to take a type argument (#13254)
• [@jest/fake-timers] Add jest.now() to return the current fake clock time (#13244, #13246)
• [@jest/mock] Add withImplementation method for temporarily overriding a mock (#13281)
• [expect] Export toThrow* matchers (#13328)

Fixes

• [jest-circus, jest-jasmine2] Fix error messages for Node's assert.throes (#13322)
• [jest-haste-map] Remove __proto__ usage (#13256)
• [jest-mock] Improve spyOn typings to handle optional properties (#13247)
• [jest-mock] Fix mocking of getters and setters on classes (#13145)
• [jest-snapshot] Throw useful error when an array is passed as property matchers (#13263)
• [jest-snapshot] Prioritize parser used in the project (#13323)
• [jest-transform] Attempt to work around issues with atomic writes on Windows (#11423)