mockable-code

Write, edit, refactor, and review code so dependencies can be replaced by mocks, stubs, fakes, or in-memory implementations without distorting production design.

Passive Trigger

Load this skill in the background whenever the task involves source code and any behavior depends on collaborators, I/O, time, randomness, persistence, configuration, network calls, queues, SDKs, process state, or framework context. Keep it lightweight for tiny edits: apply the core rules silently, then mention only the mockability decisions that affect the final implementation.

Decision Tree

What are you doing?

• Adding code that calls a dependency: Accept the dependency from the caller when practical. Keep domain policy separate from construction, configuration, and transport.

• Refactoring hard-to-test code: Read references/boundaries.md. Move side effects behind the smallest useful boundary before changing behavior.