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

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)