[Feature] Dependencies (#3)

This PR contains the work done to provide a simple dependency injection feature whenever required.

To provide further details about this work:
- [x] renamed the `Coordinator` target in the `Package` file as `Coordination`;
- [x] declared the `Dependencies` target in the `Package` file;
- [x] defined the `DependencyKey` public protocol;
- [x] implemented the `DependencyService` public service;
- [x] implemented the `Dependency` public property wrapper;

Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Reviewed-on: #3

Package.swift

@@ -14,15 +14,16 @@ let package = Package(
         .library(
             name: "SwiftLibs",
             targets: [
-                "Coordinator",
-                "Core"
+                "Coordination",
+                "Core",
+                "Dependencies"
             ]
         ),
     ],
     dependencies: [],
     targets: [
         .target(
-            name: "Coordinator",
+            name: "Coordination",
             dependencies: [],
             exclude: excludePlatforms
         ),
@@ -30,12 +31,16 @@ let package = Package(
             name: "Core",
             dependencies: []
         ),
+        .target(
+            name: "Dependencies",
+            dependencies: []
+        ),
         .testTarget(
-            name: "CoordinatorTests",
+            name: "CoordinationTests",
             dependencies: [
-                "Coordinator"
+                "Coordination"
             ],
-            path: "Tests/Coordinator",
+            path: "Tests/Coordination",
             exclude: excludePlatforms
         ),
         .testTarget(
@@ -45,6 +50,13 @@ let package = Package(
             ],
             path: "Tests/Core"
         ),
+        .testTarget(
+            name: "DependenciesTests",
+            dependencies: [
+                "Dependencies"
+            ],
+            path: "Tests/Dependencies"
+        ),
     ]
 )
 

Sources/Coordination/Platform/iOS/Routers/BaseNavigationRouter.swift

@@ -1,6 +1,6 @@
 //
 //  BaseNavigationRouter.swift
-//  Coordinator
+//  Coordination
 //
 //  Created by Javier Cicchelli on 11/04/2023.
 //  Copyright © 2023 Röck+Cöde. All rights reserved.

Sources/Coordination/Platform/iOS/Routers/ModalNavigationRouter.swift

@@ -1,6 +1,6 @@
 //
 //  ModalNavigationRouter.swift
-//  Coordinator
+//  Coordination
 //
 //  Created by Javier Cicchelli on 11/04/2023.
 //  Copyright © 2023 Röck+Cöde. All rights reserved.

Sources/Coordination/Platform/iOS/Routers/PushNavigationRouter.swift

@@ -1,6 +1,6 @@
 //
 //  PushNavigationRouter.swift
-//  Coordinator
+//  Coordination
 //
 //  Created by Javier Cicchelli on 11/04/2023.
 //  Copyright © 2023 Röck+Cöde. All rights reserved.

Sources/Coordination/Platform/iOS/Routers/WindowRouter.swift

@@ -1,6 +1,6 @@
 //
 //  WindowRouter.swift
-//  Coordinator
+//  Coordination
 //
 //  Created by Javier Cicchelli on 11/04/2023.
 //  Copyright © 2023 Röck+Cöde. All rights reserved.

Sources/Coordination/Protocols/Coordinator.swift

@@ -1,6 +1,6 @@
 //
 //  Coordinator.swift
-//  Coordinator
+//  Coordination
 //
 //  Created by Javier Cicchelli on 11/04/2023.
 //  Copyright © 2023 Röck+Cöde. All rights reserved.

Sources/Coordination/Protocols/Router.swift

@@ -1,6 +1,6 @@
 //
 //  Router.swift
-//  Coordinator
+//  Coordination
 //
 //  Created by Javier Cicchelli on 11/04/2023.
 //  Copyright © 2023 Röck+Cöde. All rights reserved.
@@ -13,7 +13,7 @@ import UIKit
 /// This protocol defines how view controllers will be shown and dismissed.
 public protocol Router: AnyObject {
     
-    // MARK: Typealiases
+    // MARK: Type aliases
     
     typealias OnDismissedClosure = () -> Void
     

Sources/Dependencies/Property Wrappers/Dependency.swift

@@ -0,0 +1,31 @@
+//
+//  Dependency.swift
+//  Dependencies
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+/// This property wrapper provides a direct connection to the `DependencyService` service.
+@propertyWrapper
+public struct Dependency<D> {
+    
+    // MARK: Properties
+    
+    private let keyPath: WritableKeyPath<DependencyService, D>
+    
+    /// This property allows direct read/write access to a defined dependency attached to a selected key path.
+    public var wrappedValue: D {
+        get { DependencyService[keyPath] }
+        set { DependencyService[keyPath] = newValue }
+    }
+    
+    // MARK: Initialisers
+    
+    /// Initialise the property wrapper by setting a key path to a defined dependency.
+    /// - Parameter keyPath: A key path to a defined dependency in the `DependencyService` service.
+    public init(_ keyPath: WritableKeyPath<DependencyService, D>) {
+        self.keyPath = keyPath
+    }
+
+}

Sources/Dependencies/Protocols/DependencyKey.swift

@@ -0,0 +1,22 @@
+//
+//  DependencyKey.swift
+//  Dependencies
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+/// This protocol defines a key to use in the dependency service.
+public protocol DependencyKey {
+    
+    // MARK: Associated types
+    
+    /// The associated type representing the type of the dependency key's value.
+    associatedtype Value
+    
+    // MARK: Properties
+    
+    /// The default value for the dependency key.
+    static var currentValue: Value { get set }
+    
+}

Sources/Dependencies/Services/DependencyService.swift

@@ -0,0 +1,28 @@
+//
+//  DependencyService.swift
+//  Dependencies
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+/// This service provide write/read access to the injected dependencies.
+public struct DependencyService {
+    
+    // MARK: Properties
+    
+    private static var current = DependencyService()
+    
+    // MARK: Subscripts
+
+    public static subscript<DK: DependencyKey>(key: DK.Type) -> DK.Value {
+        get { key.currentValue }
+        set { key.currentValue = newValue }
+    }
+    
+    public static subscript<D>(_ keyPath: WritableKeyPath<DependencyService, D>) -> D {
+        get { current[keyPath: keyPath] }
+        set { current[keyPath: keyPath] = newValue }
+    }
+
+}

Tests/Coordination/Platform/iOS/Helpers/TestCoordinators.swift

@@ -1,12 +1,12 @@
 //
 //  TestCoordinators.swift
-//  CoordinatorTests
+//  CoordinationTests
 //
 //  Created by Javier Cicchelli on 11/04/2023.
 //  Copyright © 2023 Röck+Cöde. All rights reserved.
 //
 
-import Coordinator
+import Coordination
 import UIKit
 
 // MARK: - Test coordinators

Tests/Coordination/Platform/iOS/Protocols/CoordinatorTests.swift

@@ -1,12 +1,12 @@
 //
 //  CoordinatorTests.swift
-//  CoordinatorTests
+//  CoordinationTests
 //
 //  Created by Javier Cicchelli on 11/04/2023.
 //  Copyright © 2023 Röck+Cöde. All rights reserved.
 //
 
-import Coordinator
+import Coordination
 import UIKit
 import XCTest
 

Tests/Dependencies/Helpers/TestServices.swift

@@ -0,0 +1,34 @@
+//
+//  TestServices.swift
+//  DependenciesTests
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import Dependencies
+
+// MARK: - Protocols
+
+protocol TestService {}
+
+// MARK: - Services
+
+struct SomeService: TestService, Equatable {}
+struct SomeOtherService: TestService, Equatable {}
+
+// MARK: - DependencyKey
+
+struct TestServiceKey: DependencyKey {
+    static var currentValue: TestService = SomeService()
+}
+
+// MARK: - DependencyService+Keys
+
+extension DependencyService {
+    var testService: TestService {
+        get { Self[TestServiceKey.self] }
+        set { Self[TestServiceKey.self] = newValue }
+    }
+}
+

Tests/Dependencies/Property Wrappers/DependencyTests.swift

@@ -0,0 +1,73 @@
+//
+//  DependencyTests.swift
+//  DependenciesTests
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import Dependencies
+import XCTest
+
+final class DependencyTests: XCTestCase {
+    
+    // MARK: Properties
+    
+    private var subject: TestSubject!
+    
+    // MARK: Setup
+    
+    override func setUp() {
+        DependencyService[\.testService] = SomeService()
+    }
+    
+    // MARK: Tests
+
+    func test_readTestService() {
+        // GIVEN
+        subject = .init()
+        
+        // WHEN
+        let service = subject.testService
+        
+        // THEN
+        XCTAssertNotNil(service)
+        XCTAssert(service is SomeService)
+    }
+    
+    func test_writeDependencyKey() async throws {
+        // GIVEN
+        subject = .init()
+        
+        subject.testService = SomeOtherService()
+        
+        // WHEN
+        let service = DependencyService[\.testService]
+        
+        // THEN
+        XCTAssertNotNil(service)
+        XCTAssert(service is SomeOtherService)
+    }
+    
+    func test_writeDependencyKeyTwice() async throws {
+        // GIVEN
+        subject = .init()
+        
+        subject.testService = SomeOtherService()
+        subject.testService = SomeService()
+        
+        // WHEN
+        let service = DependencyService[\.testService]
+        
+        // THEN
+        XCTAssertNotNil(service)
+        XCTAssert(service is SomeService)
+    }
+
+}
+
+// MARK: - TestSubject
+
+private struct TestSubject {
+    @Dependency(\.testService) var testService
+}

Tests/Dependencies/Services/DependencyServiceTests.swift

@@ -0,0 +1,57 @@
+//
+//  DependencyServiceTests.swift
+//  DependenciesTests
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import Dependencies
+import XCTest
+
+final class DependencyServiceTests: XCTestCase {
+
+    // MARK: Setup
+    
+    override func setUp() {
+        DependencyService[\.testService] = SomeService()
+    }
+    
+    // MARK: Tests
+
+    func test_readDependencyKey() async throws {
+        // GIVEN
+        // WHEN
+        let service = DependencyService[\.testService]
+        
+        // THEN
+        XCTAssertNotNil(service)
+        XCTAssert(service is SomeService)
+    }
+    
+    func test_writeDependencyKey() async throws {
+        // GIVEN
+        DependencyService[\.testService] = SomeOtherService()
+        
+        // WHEN
+        let service = DependencyService[\.testService]
+        
+        // THEN
+        XCTAssertNotNil(service)
+        XCTAssert(service is SomeOtherService)
+    }
+    
+    func test_writeDependencyKeyTwice() async throws {
+        // GIVEN
+        DependencyService[\.testService] = SomeOtherService()
+        DependencyService[\.testService] = SomeService()
+        
+        // WHEN
+        let service = DependencyService[\.testService]
+        
+        // THEN
+        XCTAssertNotNil(service)
+        XCTAssert(service is SomeService)
+    }
+
+}