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.