swift-protocol-di-testing

Installation
Summary

Protocol-based dependency injection for testable Swift code with focused abstractions and Swift Testing.

  • Define small, single-responsibility protocols for each external concern (file system, network, APIs) and provide default production implementations
  • Create mock implementations with configurable error properties to test failure paths deterministically without real I/O
  • Inject dependencies via default parameters so production code uses real implementations automatically while tests override with mocks
  • Ensure Sendable conformance on protocols and mocks for safe use across actor boundaries in Swift concurrency
SKILL.md

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
Related skills
Installs
3.4K
GitHub Stars
179.7K
First Seen
Feb 17, 2026