Test Automation

Test Automation

Testing Effector: Events, Stores, Effects, Sample, and Split with Jest

Effector is a reactive state manager built on the event-sourcing model. Unlike Redux, Effector has no single store — instead, you compose granular units: events, stores, and effects. This makes testing extremely straightforward: each unit is independently testable with no boilerplate. The key testing primitive is fork + allSettled, which gives

Test Automation

Vitest Browser Mode: Running Tests in Real Browsers vs jsdom

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.

Test Automation

Writing and Testing Custom Vite Plugins: Transforms, HMR, and Virtual Modules

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

Testing H3 and Nitro Server Routes: Event Handlers, Middleware, and Plugins

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

Testing Cloudflare Workers Locally with Miniflare and Wrangler

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

Test Automation

Using Biome as an All-in-One Linter and Formatter in CI

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

Test Automation

Testing Valtio Proxy State: subscribe, snapshot, Derived State, and React Integration

Valtio creates proxy state that you mutate directly. Its simplicity is also what makes testing it slightly unconventional — there's no dispatch, no reducers, and the proxy itself is mutable. The keys are using snapshot() for immutable assertions and subscribe() for testing reactive behaviour. Setup npm install valtio npm

Test Automation

Testing MobX Stores: Observables, Computed Values, Reactions, and Actions with Jest

MobX uses observable state, computed values, and reactions to build reactive systems. Testing MobX is straightforward because stores are plain classes with transparent state — no providers, no reducers, no dispatch. You call methods, read properties, and assert. Setup npm install mobx mobx-react-lite npm install -D jest @testing-library/

Test Automation

Testing Legend State: Observables, Computed, Persistence, and React Integration

Legend State is a high-performance state library built on a signals-based observable system. It's designed to minimize re-renders and handle large datasets efficiently. Testing it requires understanding how to read and write observables in tests, how to test computed values, and how to verify persistence.

Test Automation

Testing Zustand Stores: Actions, Selectors, Middleware, and Immer with Vitest

Zustand is a small, fast state management library with a minimal API. Its stores are plain JavaScript objects with actions — which makes them straightforward to test. The main challenges are resetting state between tests, testing middleware like persist and immer, and testing stores integrated with React components. Setup npm install

Test Automation

Testing XState v5 Machines: State Transitions, Guards, Actors, and Parallel States

XState v5 models application behavior as explicit state machines. Every state transition is predictable, every guard condition is explicit, and every side effect is an actor. This makes XState code highly testable — if you follow the right patterns. This guide covers testing XState v5 machines: transition testing, guard testing, actor

Test Automation

Testing Jotai Atoms: Derived Atoms, Async Atoms, Atom Families, and Suspense

Jotai is a primitive, flexible state management library built on atoms. Each atom is an independent piece of state, and atoms can derive from other atoms — synchronously or asynchronously. Testing Jotai requires understanding how to provide atom state in tests and how to handle async atoms with Suspense. Setup npm