atelier-spec-testing

Stub-driven testing is a TDD technique where you define interfaces and write tests against stubs before implementing real logic, ensuring stronger contracts between system layers and reducing brittle tests.

Apply boundary testing by isolating functional core layers—entity, service, router, repository, and consumer—and validating their design contracts independently to achieve faster feedback and resilient tests.

To start stub-driven TDD, create a minimal stub interface for your domain, write tests validating against that stub, and then implement the real logic to satisfy those tests.

Test suites become brittle across boundaries when contracts between system layers are weak; applying layer-boundary testing patterns and avoiding anti-patterns ensures maintainable, scalable tests.

Yes, stub-driven TDD applies to consumer and repository layers by validating design contracts through stubs, which improves confidence in code changes and ensures resilient tests across teams.