go-maintainable-code

Clean Architecture in Go organizes code into layers: server handles HTTP routing, service contains business logic with interfaces, and repository manages data access. Dependencies flow unidirectionally from server through service to repository, enforced via interface-based design and dependency injection with Wire.

Dependency injection decouples components by substituting implementations at runtime, enabling isolated unit testing and reducing coupling. Wire automates wiring dependencies in Go, making it straightforward to swap mock implementations during tests while maintaining clean separation of concerns.

Mock repository and external service dependencies by injecting them into service constructors during tests. This isolates business logic validation from infrastructure concerns, enabling comprehensive unit tests that verify service behavior without database or network calls.

Yes. Incrementally extract business logic into service interfaces, create repository abstractions for data access, and wire dependencies using Wire. Start with new features or targeted refactors to establish the pattern, then expand across the codebase while maintaining working code.

Context propagation threads request-scoped values, timeouts, and cancellation signals through service and repository layers. This enables coordinated shutdown, request tracing, and timeout enforcement across the call stack without passing extra parameters.

Domain-specific errors (domain.Error) encapsulate business logic failures separately from infrastructure errors, making error handling consistent and testable. This clarifies which errors are recoverable, which require user feedback, and which indicate system failures.