Testing & Mocking Packages
Testing frameworks, assertion libraries, and mocking tools for writing reliable unit, integration, and end-to-end tests (testify, pytest, Vitest).
Packages in Testing & Mocking
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Playwright
Cross-browser end-to-end web testing and browser automation with a single API for Chromium, Firefox, and WebKit.
jsdom
A pure-JavaScript implementation of the WHATWG DOM and HTML standards for Node.js.
React Testing Library
Simple and complete React DOM testing utilities that encourage good testing practices.
jest-dom
Custom Jest matchers for asserting on the state of the DOM in your tests.
user-event
Simulates the full sequence of real browser events so Testing Library tests behave the way an actual user does.
Storybook
The industry-standard workshop for building, documenting, and testing UI components in isolation, across every major frontend framework.
DOM Testing Library
Simple, framework-agnostic DOM query utilities that test your UI the way real users interact with it.
Faker
Generate massive amounts of realistic fake data for testing, seeding, and mocking in JavaScript and TypeScript.
mocha
The classic, battle-tested JavaScript test framework for Node.js and the browser, built around flexible async testing and pluggable reporters.
Chai
BDD/TDD assertion library for Node.js and the browser, framework-agnostic
pytest-xdist
Distribute pytest test runs across multiple CPUs and hosts to cut suite runtime
pytest-mock
A pytest plugin that provides a `mocker` fixture wrapping Python's `unittest.mock`, with automatic teardown between tests.
jest-junit
A Jest reporter that converts test results into JUnit-compatible XML for CI dashboards and test-analytics tools.
deep-equal
A standalone port of Node's own assert.deepEqual algorithm, giving spec-accurate deep equality checks in Node and the browser alike.
pytest-order
Pytest plugin for running tests in a specific, controllable order
chrome-remote-interface
A Node.js client for the Chrome DevTools Protocol, exposing every browser command, event, and type as a plain JavaScript API.
pytest-html
A pytest plugin that turns your test run into an interactive, shareable HTML report.
pytest-docker
Pytest fixtures that spin up Docker Compose services for integration tests, then tear them down automatically.
@sinonjs/fake-timers
Deterministic fake implementations of setTimeout, setInterval, Date, and other timer APIs for fast, reliable JavaScript tests.
pytest-cases
Separate test code from test cases in pytest, with fixture unions and parametrization goodies for readable, reusable test suites.
pytest-repeat
A pytest plugin for repeating tests a set number of times
memlab
Meta's end-to-end framework for finding JavaScript memory leaks and analyzing heap snapshots
pytest-sugar
A pytest plugin that replaces the default test runner output with a live progress bar, instant failure display, and colorized results.
user-agents
A JavaScript library that generates realistic, frequency-weighted random user agents and browser fingerprints from a dataset refreshed daily.
