Refactor example-app package manifest

Example/example-app/Package.swift

 // swift-tools-version: 5.6
-
 import PackageDescription
 
-let swiftSettings: [SwiftSetting] = [
+// MARK: - Helpers
+
+struct Feature {
+  var product: Product
+  var targets: [Target]
+  var targetDependency: Target.Dependency
+
+  static func library(
+    name: String,
+    dependencies: [Target.Dependency] = [],
+    testDependencies: [Target.Dependency] = [],
+    swiftSettings: [SwiftSetting] = [
       .unsafeFlags(
         [
           "-Xfrontend",
@@ -13,170 +23,158 @@ let swiftSettings: [SwiftSetting] = [
         .when(configuration: .debug)
       ),
     ]
-
-let package = Package(
-  name: "example-app",
-  platforms: [
-    .iOS(.v15),
-  ],
-  products: [
-    .library(
-      name: "AppFeature",
-      targets: ["AppFeature"]
-    ),
-    .library(
-      name: "ErrorFeature",
-      targets: ["ErrorFeature"]
-    ),
-    .library(
-      name: "LandingFeature",
-      targets: ["LandingFeature"]
+  ) -> Feature {
+    .init(
+      product: .library(name: name, targets: [name]),
+      targets: [
+        .target(
+          name: name,
+          dependencies: dependencies,
+          swiftSettings: swiftSettings
         ),
-    .library(
-      name: "SessionFeature",
-      targets: ["SessionFeature"]
+        .testTarget(
+          name: "\(name)Tests",
+          dependencies: [.target(name: name)] + testDependencies,
+          swiftSettings: swiftSettings
         ),
       ],
-  dependencies: [
-    .package(path: "../../"), // elixxir-dapps-sdk-swift
-    .package(
+      targetDependency: .target(name: name)
+    )
+  }
+}
+
+struct Dependency {
+  var packageDependency: Package.Dependency
+  var targetDependency: Target.Dependency
+
+  static func local(
+    path: String,
+    name: String,
+    package: String
+  ) -> Dependency {
+    .init(
+      packageDependency: .package(path: path),
+      targetDependency: .product(name: name, package: package)
+    )
+  }
+
+  static func external(
+    url: String,
+    version: Range<Version>,
+    name: String,
+    package: String
+  ) -> Dependency {
+    .init(
+      packageDependency: .package(url: url, version),
+      targetDependency: .product(name: name, package: package)
+    )
+  }
+}
+
+// MARK: - Manifest
+
+extension Dependency {
+  static let all: [Dependency] = [
+    .composableArchitecture,
+    .composablePresentation,
+    .elixxirDAppsSDK,
+    .keychainAccess,
+    .xcTestDynamicOverlay,
+  ]
+
+  static let composableArchitecture = Dependency.external(
     url: "https://github.com/pointfreeco/swift-composable-architecture.git",
-      .upToNextMajor(from: "0.35.0")
-    ),
-    .package(
-      url: "https://github.com/darrarski/swift-composable-presentation.git",
-      .upToNextMajor(from: "0.5.2")
-    ),
-    .package(
-      url: "https://github.com/kishikawakatsumi/KeychainAccess.git",
-      .upToNextMajor(from: "4.2.2")
-    ),
-    .package(
-      url: "https://github.com/pointfreeco/xctest-dynamic-overlay.git",
-      .upToNextMajor(from: "0.3.3")
-    ),
-  ],
-  targets: [
-    .target(
-      name: "AppFeature",
-      dependencies: [
-        .target(name: "ErrorFeature"),
-        .target(name: "LandingFeature"),
-        .target(name: "SessionFeature"),
-        .product(
+    version: .upToNextMajor(from: "0.38.3"),
     name: "ComposableArchitecture",
     package: "swift-composable-architecture"
-        ),
-        .product(
+  )
+
+  static let composablePresentation = Dependency.external(
+    url: "https://github.com/darrarski/swift-composable-presentation.git",
+    version: .upToNextMajor(from: "0.5.2"),
     name: "ComposablePresentation",
     package: "swift-composable-presentation"
-        ),
-        .product(
+  )
+
+  static let elixxirDAppsSDK = Dependency.local(
+    path: "../../",
     name: "ElixxirDAppsSDK",
     package: "elixxir-dapps-sdk-swift"
-        ),
-        .product(
+  )
+
+  static let keychainAccess = Dependency.external(
+    url: "https://github.com/kishikawakatsumi/KeychainAccess.git",
+    version: .upToNextMajor(from: "4.2.2"),
     name: "KeychainAccess",
     package: "KeychainAccess"
-        ),
-        .product(
+  )
+
+  static let xcTestDynamicOverlay = Dependency.external(
+    url: "https://github.com/pointfreeco/xctest-dynamic-overlay.git",
+    version: .upToNextMajor(from: "0.3.3"),
     name: "XCTestDynamicOverlay",
     package: "xctest-dynamic-overlay"
-        ),
-      ],
-      swiftSettings: swiftSettings
-    ),
-    .testTarget(
-      name: "AppFeatureTests",
+  )
+}
+
+extension Feature {
+  static let all: [Feature] = [
+    .app,
+    .error,
+    .landing,
+    .session,
+  ]
+
+  static let app = Feature.library(
+    name: "AppFeature",
     dependencies: [
-        .target(name: "AppFeature"),
-      ],
-      swiftSettings: swiftSettings
-    ),
-    .target(
+      Feature.error.targetDependency,
+      Feature.landing.targetDependency,
+      Feature.session.targetDependency,
+      Dependency.composableArchitecture.targetDependency,
+      Dependency.composablePresentation.targetDependency,
+      Dependency.elixxirDAppsSDK.targetDependency,
+      Dependency.keychainAccess.targetDependency,
+      Dependency.xcTestDynamicOverlay.targetDependency,
+    ]
+  )
+
+  static let error = Feature.library(
     name: "ErrorFeature",
     dependencies: [
-        .product(
-          name: "ComposableArchitecture",
-          package: "swift-composable-architecture"
-        ),
-        .product(
-          name: "ElixxirDAppsSDK",
-          package: "elixxir-dapps-sdk-swift"
-        ),
-        .product(
-          name: "XCTestDynamicOverlay",
-          package: "xctest-dynamic-overlay"
-        ),
-      ],
-      swiftSettings: swiftSettings
-    ),
-    .testTarget(
-      name: "ErrorFeatureTests",
-      dependencies: [
-        .target(name: "ErrorFeature"),
-      ],
-      swiftSettings: swiftSettings
-    ),
-    .target(
+      Dependency.composableArchitecture.targetDependency,
+      Dependency.elixxirDAppsSDK.targetDependency,
+      Dependency.xcTestDynamicOverlay.targetDependency,
+    ]
+  )
+
+  static let landing = Feature.library(
     name: "LandingFeature",
     dependencies: [
-        .target(name: "ErrorFeature"),
-        .product(
-          name: "ComposableArchitecture",
-          package: "swift-composable-architecture"
-        ),
-        .product(
-          name: "ComposablePresentation",
-          package: "swift-composable-presentation"
-        ),
-        .product(
-          name: "ElixxirDAppsSDK",
-          package: "elixxir-dapps-sdk-swift"
-        ),
-        .product(
-          name: "XCTestDynamicOverlay",
-          package: "xctest-dynamic-overlay"
-        ),
-      ],
-      swiftSettings: swiftSettings
-    ),
-    .testTarget(
-      name: "LandingFeatureTests",
-      dependencies: [
-        .target(name: "LandingFeature"),
-      ],
-      swiftSettings: swiftSettings
-    ),
-    .target(
+      Feature.error.targetDependency,
+      Dependency.composableArchitecture.targetDependency,
+      Dependency.composablePresentation.targetDependency,
+      Dependency.elixxirDAppsSDK.targetDependency,
+      Dependency.xcTestDynamicOverlay.targetDependency,
+    ]
+  )
+
+  static let session = Feature.library(
     name: "SessionFeature",
     dependencies: [
-        .target(name: "ErrorFeature"),
-        .product(
-          name: "ComposableArchitecture",
-          package: "swift-composable-architecture"
-        ),
-        .product(
-          name: "ComposablePresentation",
-          package: "swift-composable-presentation"
-        ),
-        .product(
-          name: "ElixxirDAppsSDK",
-          package: "elixxir-dapps-sdk-swift"
-        ),
-        .product(
-          name: "XCTestDynamicOverlay",
-          package: "xctest-dynamic-overlay"
-        ),
-      ],
-      swiftSettings: swiftSettings
-    ),
-    .testTarget(
-      name: "SessionFeatureTests",
-      dependencies: [
-        .target(name: "SessionFeature"),
-      ],
-      swiftSettings: swiftSettings
-    ),
+      Feature.error.targetDependency,
+      Dependency.composableArchitecture.targetDependency,
+      Dependency.composablePresentation.targetDependency,
+      Dependency.elixxirDAppsSDK.targetDependency,
+      Dependency.xcTestDynamicOverlay.targetDependency,
     ]
   )
+}
+
+let package = Package(
+  name: "example-app",
+  platforms: [.iOS(.v15)],
+  products: Feature.all.map(\.product),
+  dependencies: Dependency.all.map(\.packageDependency),
+  targets: Feature.all.flatMap(\.targets)
+)