Testing

Review the tools available for testing and debugging Workers.

Testing comparison matrix

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

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