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Software Engineering•January 20, 2024•8 min read

Vitest: Fast Unit Testing for Modern JavaScript

Vitest provides Jest-compatible testing with native ESM support and Vite integration.

#vitest#testing#vite#jest

Vitest leverages Vite for fast test execution. Jest-compatible API eases migration. Native ESM support works without configuration. Watch mode re-runs affected tests instantly.

Configuration

Configure through vite.config.ts or vitest.config.ts. Share configuration with your Vite application. Set up coverage with v8 or istanbul. Configure test environment for DOM or Node.

  • Use Jest-compatible assertions and mocks
  • Configure coverage thresholds for CI
  • Enable watch mode for rapid development
  • Use workspace mode for monorepo testing
  • Run benchmarks with vitest bench

Performance

Vite's transform pipeline accelerates tests. Worker threads parallelize test files. Smart watch mode minimizes re-runs. Typical projects see 2-3x speed improvement over Jest.

Tags

vitesttestingvitejestunit-testing