swift-protocol-di-testing

name	swift-protocol-di-testing
description	Protocol-based dependency injection for testable Swift code — mock file system, network, and external APIs using focused protocols and Swift Testing.
license	MIT
compatibility	opencode
metadata	{"origin":"claude-skills","type":"workflow"}

Swift Protocol-Based Dependency Injection for Testing

Patterns for making Swift code testable by abstracting external dependencies (file system, network, iCloud) behind small, focused protocols. Enables deterministic tests without I/O.

When to Activate

• Writing Swift code that accesses file system, network, or external APIs
• Need to test error handling paths without triggering real failures
• Building modules that work across environments (app, test, SwiftUI preview)
• Designing testable architecture with Swift concurrency (actors, Sendable)

Core Pattern

1. Define Small, Focused Protocols

Each protocol handles exactly one external concern.

// File system access
public protocol FileSystemProviding:  {
     ( : ) -> ?
}


  :  {
     ( : )  -> 
     ( : ,  : ) 
     ( : ) -> 
}


  :  {
     ( : ,  : ) 
     ( : )  -> ?
}