What problem does it solve? Writing test doubles for Go interfaces by hand is repetitive boilerplate: every interface needs a stub, an in-memory version, an error-injecting version, and a call-recording fake. This Skill automates creating that full implementation package, or audits an existing package and fills in whichever doubles are missing. ## Core Features & Use Cases - Create new implementation packages: Given an interface like checkpoint.Store, it parses all method signatures and scaffolds blank.go, memory.go, broken.go, fake.go, and memory_test.go in the correct package path. - Review existing packages: Given a path to an implementation package, it detects which doubles exist and generates only the missing ones. - Consistent testing patterns: Every file includes a compile-time interface assertion (var _ Interface = (*Impl)(nil)), fluent error configuration for the broken double, empty and pre-populated factories for memory, and testify-based tests. - Use Case: While writing unit tests for a service that depends on a storage interface, invoke the Skill with the interface name to instantly get an in-memory implementation for happy-path tests and a broken implementation for error-path tests. ## Quick Start Ask the AI to run the implement-go-interface skill on the checkpoint.Store interface to generate the full set of test doubles.
