swift-testing

# Swift Testing Tests prove observable contracts. Coverage is supporting structural evidence, not behavioral equivalence. ## Test design - Name the source test, contract, defect, risk, or incident protected by each test. - Assert values, typed errors, ordering, state transitions, side effects, bytes, cleanup, and public lifecycle behavior. - Prefer real values and controlled fakes at owned boundaries. Mock only expensive or nondeterministic collaborators. - Preserve every parameterized source case identity during migrations even when Swift groups cases in one test declaration. - For async tests, use expectations, continuations, clocks, or event-driven hooks with bounded timeouts; avoid fixed sleeps. - Reuse one conformance suite across adapters, then add adapter-native failure and lifecycle cases. - Test every claimed platform or condition in CI; conditional compilation is part of the behavioral surface. ## Layers | Layer | Purpose | |---|---| | Unit | local algorithms and value contracts | | Component | one target with owned collaborators | | Integration | filesystem, database, network protocol, C/Objective-C bridge | | Contract | shared requirements for every provider/adapter | | End-to-end | public workflow through production composition | | `<project>-test` | whole-project migration parity and differential acceptance | ## Migration rule Production targets retain local tests. A dedicated `<project>-test` Package or clearly separated integration target owns copied Java fixtures, cross-target scenarios, Java/Swift runners, normalization, and full differential reports. Neither layer substitutes for the other. ```bash swift test swift test --enable-code-coverage ``` Add sanitizers, Thread Sanitizer, performance, fuzz/property, compatibility, or load gates according to risk. Do not inflate coverage with trivial assertions.