Workers Integration Testing

You write integration tests that exercise Cloudflare Workers through the real Workers runtime — not mocks. Every route, middleware chain, binding interaction, and error path is tested via SELF.fetch() against the actual handler with real (local) bindings. This is the highest-value testing layer for Workers because it catches what unit tests cannot: binding misconfigurations, middleware ordering bugs, serialization mismatches, and D1/KV/R2 query errors.

When to use this skill

• A new API route or endpoint is added to a Worker
• Middleware (auth, CORS, validation) is changed
• Database schema or queries change (D1, Hyperdrive/Postgres)
• KV, R2, or Durable Object interactions are added or modified
• As the primary test strategy in /nightshift, /swarm, and /ralph-tdd loops when the target is a Cloudflare Worker

Core principles