Testing

Review the tools available for testing and debugging Workers.

• Unit testing
• Integration testing
• Vitest integration
• Miniflare

Testing comparison matrix

Feature	Vitest Pool	unstable_dev()	Miniflare's API
Unit testing	✅	❌	❌
Integration testing	✅	✅	✅
Loading wrangler.toml / wrangler.json files	✅	✅	❌
Bindings directly in tests	✅	❌	✅
Isolated per-test storage	✅	❌	❌
Outbound request mocking	✅	❌	✅
Multiple Worker support	✅	🚧1	✅
Direct access to Durable Objects	✅	❌	❌
Run Durable Object alarms immediately	✅	❌	❌
List Durable Objects	✅	❌	❌
Testing service Workers	❌	✅	✅

Pages Functions

The content described on this page is also applicable to Pages Functions. Pages Functions are Cloudflare Workers and can be thought of synonymously with Workers in this context.

Footnotes

1. Support for multiple Workers in unstable_dev() relies on wrangler dev's service registry which can be unreliable when running multiple tests in parallel. ↩