go-interface-design

Design Go interfaces for testability by defining them on the consumer side, keeping them small with 1–3 methods, and returning concrete types to ensure decoupled, composable contracts.

Consumer-side Go interfaces prevent import cycles and bloated abstractions by declaring contracts where they are consumed, ensuring dependencies remain focused on specific client needs rather than broad implementations.

Structure Go interfaces for code review by preferring small 1–3 method contracts, verifying compile-time compliance assertions, avoiding pointers to interfaces, and replacing empty interface usage with generics or narrower types.

Verify compile-time compliance for Go interface implementations by using compile-time assertions, ensuring concrete types satisfy consumer-side contracts during package design and refactors without runtime checks.

Avoid the empty interface in Go when narrower types or generics provide better type safety, as gratuitous empty interface usage increases coupling and reduces compile-time verification during package design.

Return concrete types instead of interfaces in Go package design to preserve implementation flexibility, while accepting interfaces at the consumer side to maintain decoupled and testable code.