Test Contract Define behavioral contracts as test suites. Any class conforming to a protocol must pass the contract tests. Ensures consistent behavior across implementations — human-written, AI-generated, or mock. When This Skill Activates Use this skill when the user: - Designs a protocol and wants to ensure conformance quality - Has multiple implementations of the same interface (e.g., real + mock + in-memory) - Says "test the protocol" or "contract test" - Wants to swap implementations safely (e.g., CoreData → SwiftData) - Wants to ensure AI-generated implementations meet the spec Why Cont…