Shared Fakes Across a Monorepo: One Test Double from Frontend to Backend

Originally published at recca0120.github.io The previous post covered DI + Fake + in-memory basics . This one takes it further, into a scenario most testing tutorials ignore: how frontend, backend, and shared logic can use the same Fake in a monorepo . Scope of this post : internal services — classes you wrote, with interfaces you can swap. If the dependency is an external HTTP API (Stripe, GitHub, third-party SaaS), Fake isn't the right tool. See part three on shared HTTP mocks for that case. T