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
Kind
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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.
pytest
The Python testing framework that makes writing small tests easy and scales to complex functional test suites.
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
pluggy
The minimalist, production-ready plugin and hook system that powers pytest, tox, and devpi
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.
Faker
A Python library that generates realistic fake data for testing, seeding, and anonymizing datasets across 70+ locales.
hypothesis
Property-based testing for Python that generates edge cases and shrinks failures to their simplest reproducing example.
fake-useragent
Up-to-date user-agent string faker backed by a real-world browser usage database, bundled offline.
fakeredis
A pure-Python, in-memory implementation of the Redis protocol for testing.
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.
behave
A Python behavior-driven development framework that runs Gherkin feature files against step definitions written in plain Python.
testcontainers-python
Throwaway Docker containers for real integration tests, driven straight from Python.
pytest-html
A pytest plugin that turns your test run into an interactive, shareable HTML report.
mock
The rolling backport of Python's unittest.mock library
