Vitest

Vitest — Vite-native test framework with Jest-compatible API.

TestingSimple

Stack Components

FrameworkVitest 2.x

BaseVite

Why

Vite-powered fast transforms, ESM-native, watch mode, in-source testing, UI. 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 Vite projects. Avoid for non-Vite legacy projects.

How

1. npm install vitest 2. Write *.test.ts 3. npx vitest 4. npx vitest ui 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, expect } from 'vitest'; test('add', () => { expect(1 + 1).toBe(2); });

Common Problems

⚠Module resolution — use deps.inline for CJS
⚠Coverage — install @vitest/coverage-v8
⚠Configuration drift between environments — use infrastructure-as-code (Terraform/Pulumi) to keep dev/staging/prod identical

Best Practices

✓Use vi.mock for mocking
✓Leverage test.concurrent for parallel tests
✓Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit

FAQ

What is Vitest and what projects is it for?

Vitest — Vite-native test framework with Jest-compatible API. 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 Vitest in 10 minutes?

Two steps: (1) npm install vitest; (2) Write *.test.ts. 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 Vitest and how do I avoid it?

The most common pitfall is: Module resolution — use deps.inline for CJS. 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 Vitest?

Best practices for Vitest include: Use vi.mock for mocking; Leverage test.concurrent for parallel tests; Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit. The first one — "Use vi.mock for mocking" — should be set up at project init to avoid costly rework later.

When should I NOT choose Vitest?

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). Vitest shines for mid-to-high complexity full-stack and API work — don't over-engineer simple static pages with it.