usecase-pattern

Refactor large methods into testable use cases by creating orchestration units that enforce consistent dependency injection, guard clauses, and immutable updates. This separates business flows from UI and state, ensuring deterministic behavior across app modules.

Coordinate domain use cases by defining a single entry point via a call(...) method with constructor-injected dependencies. This pattern enforces guard clauses and delegates persistence or service calls to separate concerns for clean orchestration.

Constructor injection in domain-driven use cases supplies required dependencies upfront, ensuring the call(...) method operates with fully initialized services. This enables immutable updates and deterministic, testable orchestration flows without hidden dependencies.

Use guard clauses in business logic orchestration to enforce preconditions and prevent invalid state transitions early. Combined with immutable updates, they ensure deterministic behavior and simplify testing by failing fast before executing the core workflow.

Immutable updates work with delegated persistence by ensuring the use case call(...) method does not mutate state directly. Instead, it delegates persistence or service calls to injected dependencies, keeping orchestration logic separate and deterministic.

Separating orchestration logic from UI and repositories improves testability by isolating business flows into single-entry-point use cases. This allows you to inject mock dependencies, verify guard clauses, and test immutable updates without triggering UI or database side effects.