TanStack Start Testing

Select the smallest meaningful check

Read ../../docs/testing-and-debugging.md. Map the changed behavior to its owning boundary and reproduce the failure before editing when possible.

1. Test pure validators and domain logic.
2. Test server functions, middleware, or server routes through their public contract.
3. Test route matching, params, search, loaders, and boundaries.
4. Run typecheck, configured lint, and production build.
5. Reproduce browser-visible behavior and inspect console and network output.

Use the project's existing runner and conventions. Ask before installing a test framework or changing configuration.

Cover failure paths

Include malformed input, authentication, authorization, cross-tenant access, dependency failure, redirect, not-found, status/header behavior, hydration mismatch, direct load, and client navigation as relevant.

Diagnose without masking