What problem does it solve? SwiftData tests often fail intermittently or silently corrupt device state because they share ModelContexts, write to the real persistent store, or cross @ModelActor boundaries incorrectly. This Skill writes and reviews SwiftData test code so it runs in isolation, uses in-memory storage, and catches failure modes specific to @Model, @ModelActor, and Decimal money values. ## Core Features & Use Cases - In-Memory Test Fixtures: Builds fresh ModelContainer fixtures with isStoredInMemoryOnly per test, eliminating cross-test state leakage and device-store mutation. - Mock Repository Pattern: Replaces real ModelContainers in ViewModel unit tests with protocol-based in-memory mocks that run in microseconds. - Actor-Safe Testing: Enforces DTO/PersistentIdentifier patterns across @ModelActor boundaries instead of passing @Model instances. - Specialized Assertions: Covers Decimal money-value exact-equality assertions and content-hash dedup idempotency tests for CSV/API imports. - Use Case: When reviewing a SwiftData-backed app's test suite, the Skill flags a shared ModelContext across tests, a migrationPlan applied to an in-memory config, and epsilon-based Decimal comparisons, then shows before/after fixes. ## Quick Start Ask the assistant to review the SwiftData test files in this project and fix any tests that share containers, touch the real store, or cross actor boundaries.
