Vitest Configuration Generator

Vitest is a Vite-powered test framework compatible with Jest's API. It's significantly faster (uses native ES modules, no transpilation), has first-class TypeScript support, integrates natively with Vite, and shares your vite.config.ts configuration. If you're using Vite, Vitest is the natural choice. If you're not using Vite, it's still faster than Jest for TypeScript projects because it skips the babel/ts-jest setup.

Use node (default) for backend code, utilities, and APIs — it's the fastest. Use jsdom for React/Vue/Angular component tests — it simulates a browser DOM in Node.js. Use happy-dom for the same purpose as jsdom but with better performance (less complete browser compatibility). Use edge-runtime for Cloudflare Workers or Vercel Edge Functions.

v8 uses Node.js's built-in V8 coverage engine — it's fast and requires no instrumentation (install @vitest/coverage-v8). istanbul instruments your code by injecting counters — it's slower but more accurate, especially for complex code paths (install @vitest/coverage-istanbul). For most projects, v8 is sufficient. Use istanbul if you need precise branch coverage on complex conditional logic.

globals: true injects describe, it, expect, beforeEach, etc. globally — you don't need to import them in test files, matching Jest behavior. The tradeoff is that these global variables aren't type-checked unless you add @types/vitest to your tsconfig.json types array. For new projects, explicit imports (import { describe, it, expect } from 'vitest') are more explicit and don't require any extra setup.

Use it.only() or test.only() to run a single test. Use describe.only() for a block. Run vitest -t 'test name pattern' to filter by name. Use vitest run --reporter=verbose for detailed output. Vitest also has a UI mode: npx vitest --ui gives you a browser-based test explorer with real-time test results.

Run vitest run (not vitest watch) in CI to execute once and exit. Add --reporter=junit to generate a JUnit XML report for CI dashboards. Add --coverage to generate coverage reports. Use --coverage.thresholds to fail the build if coverage drops. Example: vitest run --reporter=junit --coverage --outputFile=test-results.xml