iOS Testing Best Practices Comprehensive testing guide for iOS and Swift applications, written at principal engineer level. Contains 44 rules across 8 categories, prioritized by impact to guide test architecture decisions, test authoring patterns, and CI infrastructure. Clinic Architecture Contract (iOS 26 / Swift 6.2) All guidance in this skill assumes the clinic modular MVVM-C architecture: - Feature modules import + only (never , never sibling features) - App target is the convergence point and owns , concrete coordinators, and Route Shell wiring - stays pure Swift and defines models plus…