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Vitest integration

For most users, Cloudflare recommends using the Workers Vitest integration for unit testing Workers and Pages Functions projects. Vitest ↗ is a popular JavaScript testing framework featuring a fast watch mode, Jest compatibility, and default TypeScript support. Cloudflare provides the @cloudflare/vitest-plugin Vite plugin, which runs your Vitest tests inside the Workers runtime.

The Workers Vitest integration:

• Supports both unit tests and integration tests.
• Provides direct access to Workers runtime APIs and bindings.
• Implements isolated per-test-file storage.
• Runs tests fully-locally using Miniflare ↗.
• Leverages Vitest's hot-module reloading for near instant reruns.
• Supports projects with multiple Workers.

If you use @cloudflare/vitest-pool-workers, refer to Migrate to Vitest plugin.