uvu

uvu — ultra-lightweight test runner, 1KB, no dependencies.

TestingSimple

Stack Components

Frameworkuvu 0.x

Why

1KB bundle, ESM-native, fast startup, great for edge/CI. Vitest replaced Jest for Vite projects, running 3x faster with native ESM.

Playwright became the #1 E2E tool in 2024, surpassing Cypress with cross-browser support and auto-waiting.

When

Use for minimal test setups. Avoid for complex mocking needs.

How

1. npm install uvu 2. Create suite with uvu() 3. Run test() 4. View results 5. Add environment configuration — cp .env.example .env && edit values 6. Run tests — npm test or pnpm test to verify setup 7. Deploy — git push to trigger CI/CD or manual deploy

Example

import { test, suite } from 'uvu'; const math = suite('math'); math('add', () => { /* assert */ }); math.run();

Common Problems

⚠No built-in mocking — use tinyspy
⚠No watch mode — use chokidar
⚠Configuration drift between environments — use infrastructure-as-code (Terraform/Pulumi) to keep dev/staging/prod identical

Best Practices

✓Use uvu/assert for assertions
✓Run in parallel with multiple processes
✓Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit

FAQ

What is uvu and what projects is it for?

uvu — ultra-lightweight test runner, 1KB, no dependencies. It pairs layered technologies for end-to-end type safety and out-of-the-box deploys, fitting everything from MVPs to production SaaS.

How do I spin up a working demo with uvu in 10 minutes?

Two steps: (1) npm install uvu; (2) Create suite with uvu(). Get the local dev server running, then wire one real data source to verify the end-to-end loop.

What is the most common pitfall with uvu and how do I avoid it?

The most common pitfall is: No built-in mocking — use tinyspy. Avoid it by adding the matching checklist to your PR template and running type-check + lint + unit tests in CI — three gates before merge.

What are the best practices for uvu?

Best practices for uvu include: Use uvu/assert for assertions; Run in parallel with multiple processes; Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit. The first one — "Use uvu/assert for assertions" — should be set up at project init to avoid costly rework later.

When should I NOT choose uvu?

Pick something else in three cases: (1) the team has zero experience with the core framework and the deadline is tight (learning-curve risk); (2) it's a pure content/marketing site (Astro is lighter); (3) you need very high throughput (>10k RPS) or strict-consistency microservices (Go/Rust). uvu shines for mid-to-high complexity full-stack and API work — don't over-engineer simple static pages with it.