domain-logic-module

To isolate domain logic, you encapsulate domain rules and invariants into a dedicated, testable module boundary, preventing them from leaking into controllers, jobs, or adapters. This approach enforces strict invariants across backend service boundaries.

The best way to unit test business logic invariants is to refactor domain rules into a testable module boundary with defined inputs and outputs. This setup supports unit tests by providing deterministic error behavior through encoded preconditions and postconditions.

Refactoring domain rules involves consolidating them into a clear API surface module that enforces invariants with preconditions and postconditions. This scalable refactoring maintains deterministic errors while ensuring rules apply uniformly across controllers and adapters.

Yes, encapsulating domain rules into a module boundary supports scalable refactoring of business logic. By enforcing rules through a clear API surface and deterministic error behavior, the module maintains strict invariants while the surrounding backend services scale.

You need to consolidate business logic into a dedicated module boundary when invariants begin leaking into controllers, jobs, or adapters. This process is applicable to backend services requiring strict invariants, clear module interfaces, and deterministic unit tests.