use-case-modeling

Express use case acceptance criteria as durable postconditions like system state changes, emitted events, or externally observable side effects rather than relying on transient UI text. This ensures outcomes remain testable and unambiguous across implementation changes.

Model external systems as actors with explicit trust-boundary preconditions and dedicated failure paths. This risk-aware approach handles webhook duplicates, payment timeouts, and state preservation by enforcing idempotency and complete recovery behavior for every external interaction.

A fully-dressed use case template specifies an actor-goal interaction with explicit scope, preconditions, triggers, main paths, alternate paths, failure paths, and durable postconditions. It converts stakeholder goals into precisely specified, testable behavioral contracts.

Reference named business rules by ID directly within your use case specification. This enforces traceability so designs and tests can be verified against authoritative rules and guarantees that behavioral paths satisfy named rule constraints.

Use case modeling handles billing workflows by specifying a main path for successful subscription while explicitly modeling alternate paths for coupon validation failures and payment timeouts, ensuring acceptance criteria and recovery behavior remain unambiguous.

Avoid using UI text as a postcondition when acceptance criteria must be derived directly from durable behavioral guarantees. Relying on UI messages creates brittle tests; instead, specify state changes or emitted events to ensure complete, testable outcomes for every path.