full-stack-skills/swift-skills/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

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.

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.