Classify test doubles and apply Testcontainers for real middleware integration testing.
npx skills add https://github.com/Hakkadaikon/hymme --skill test-doubles-hakkadaikon
Please help me install this Agent Skill. Skill: test-doubles Source: https://github.com/Hakkadaikon/hymme/tree/main/skills/test-doubles Command: npx skills add https://github.com/Hakkadaikon/hymme --skill test-doubles-hakkadaikon
High-intent search queries and answers about installing and using this skill.
A stub supplies input to the system under test by returning prepared values and is never verified. A mock verifies outgoing calls to external collaborators using assertions like toHaveBeenCalledWith. Combining both roles in one double signals oversized responsibilities.
Use a fake like an in-memory repository for fast tests where contract fidelity is not critical. Use Testcontainers with the real database engine when SQL dialects, transaction isolation, or constraints matter, since fakes can diverge from production behavior.
Use Testcontainers for managed out-of-process dependencies like your own PostgreSQL database, where mocking would couple tests to repository implementation details. Reserve it for a small set of integration tests since container startup is much slower than unit tests.
Verifying stubs with toHaveBeenCalled creates over-specification, locking tests to input-supply details that should be free to change. Only verify mocks that represent outputs to unmanaged external systems, and check stub-supplied values through observable results instead.
Yes, the @testcontainers/postgresql package integrates with vitest using beforeAll to start the container and afterAll to stop it. Give startup a generous timeout such as 60 seconds and keep test data isolated between cases.
xiaolaiBuilds a test matrix with assertion strategy, lane, and spec level per case.
jpeggdevGuide developers through the Red-Green-Refactor cycle for Test-Driven Development.
Nandansai08Selects the correct test double type for unit tests based on what each test verifies.
StudentCristianAutomate property-based and mutation testing across Python and JavaScript.
