JavaScript
Storybook 8 expanded from a documentation tool into a component testing platform. The key additions are play functions (interaction tests that run inside the browser), portable stories (importing stories into Vitest or Jest), and the Storybook test runner that executes all play functions in CI. Together they let you write
React
Ladle is a fast, lightweight alternative to Storybook for developing and documenting React components. It uses Vite instead of Webpack, which means near-instant startup and hot module replacement measured in milliseconds rather than seconds. Ladle is compatible with the CSF (Component Story Format) that Storybook uses, so migrating existing stories
JavaScript
Faker.js (@faker-js/faker) generates realistic fake data for tests and seeding. The basics — faker.person.firstName(), faker.internet.email() — are straightforward. The advanced features are what make Faker useful for complex test data: custom providers for domain-specific data, locales for internationalization testing, seeded randomness for reproducible test runs, and
wasm-bindgen
wasm-bindgen is the bridge between Rust WebAssembly and JavaScript. It generates the glue code that lets JS call Rust functions, pass complex types across the boundary, and use JavaScript APIs from Rust. That bridge is a rich source of bugs: type mismatches, ownership errors at the boundary, and behavior differences
Test Automation
Vitest's browser mode runs your tests inside a real browser instead of a simulated DOM environment like jsdom or happy-dom. This matters because jsdom does not execute real JavaScript rendering, does not run CSS layout, and does not implement browser APIs like ResizeObserver, IntersectionObserver, or Web Components. When
Test Automation
Vite plugins extend the build pipeline with custom transforms, virtual modules, and build hooks. Testing them is harder than testing application code because a plugin's behavior is entangled with Vite's internals — module graphs, HMR events, rollup hooks. This guide covers a practical, reproducible approach to testing
Test Automation
H3 is the HTTP framework that powers Nitro, which in turn powers Nuxt 3's server engine. If you write server/api/*.ts or server/routes/*.ts files in a Nuxt project, you are writing H3 event handlers. Testing these handlers in isolation — without starting a full Nuxt or
Test Automation
Cloudflare Workers run in V8 isolates, not Node.js. That difference means standard testing approaches break: node:fs, node:http, and most Node.js built-ins are unavailable. Miniflare solves this by implementing the Workers runtime APIs locally — KV, R2, D1, Durable Objects, Queues — so your tests run in an environment
Test Automation
Biome is a high-performance JavaScript and TypeScript toolchain that replaces ESLint, Prettier, and several other tools with a single binary. It is written in Rust, has near-zero configuration overhead, and runs lint checks 10–100× faster than the Node.js equivalents. This guide covers everything you need to integrate Biome
Testing
Web Push notifications rely on three moving parts: VAPID authentication, encrypted payloads using the Web Cryptography API, and browser subscription endpoints from push services like FCM or Mozilla's autopush. Testing all three layers without a real browser is entirely possible — this guide shows how using pywebpush in Python
Database Testing
Sequelize has been a cornerstone of Node.js database development for over a decade. While newer ORMs have taken some of the spotlight, millions of production applications still run on Sequelize, and many teams are actively maintaining large Sequelize codebases that need solid test coverage. Testing Sequelize effectively is more
Testing
SendGrid powers email delivery for many production applications. Testing SendGrid integration involves mocking the API client for unit tests, using SendGrid's sandbox mode for integration tests, and testing Event Webhooks for delivery tracking. This guide covers all three layers with Node.js examples. Key Takeaways Enable sandbox mode