Test Strategy

Choose the smallest test boundary that proves the observable behavior at risk. For complex features, prefer repeatable end-to-end coverage where practical, especially when a failure crosses system boundaries or only the assembled product can expose it. A smaller boundary is cheaper and clearer for a local, stable failure mode; account for end-to-end runtime and flakiness costs.

Establish the failure contract

Before choosing checks or changing behavior, state the externally observable result and invariant at risk. Identify plausible failure modes, then select only the cases that expose a real gap at the chosen boundary.

Check, implement, verify