Enable a dependency root to receive a renamed @Instantiated property (#…

…43)

README.md

@@ -247,7 +247,7 @@ public final class UpdateUserService {
 
 #### Renaming and retyping dependencies
 
-It is possible to rename or retype a dependency that is `@Instantiated` or `@Forwarded` by an object higher up in the dependency tree with the `@Received` macro. Renamed or retyped dependencies are able to be received with their new name and type by objects instantiated further down the dependency tree.
+It is possible to rename or retype a dependency that is `@Instantiated` or `@Forwarded` by an object higher up in the dependency tree with the `@Received(fulfilledByDependencyNamed:ofType:)` macro. Renamed or retyped dependencies are able to be received with their new name and type by objects instantiated further down the dependency tree.
 
 Here we have an example of a `UserManager` type that is received as a `UserVendor` further down the dependency tree.
 
@@ -379,8 +379,9 @@ SafeDI automatically finds the root(s) of your dependency tree, and creates an e
 
 An `@Instantiable` type qualifies as the root of a dependency tree if and only if:
 
-1. The type‘s SafeDI-injected properties are all `@Instantiated`
-2. The type is not instantiated by another `@Instantiable` type
+1. The type‘s SafeDI-injected properties are all `@Instantiated` or `@Received(fulfilledByDependencyNamed:ofType:)`
+2. The type‘s `@Received(fulfilledByDependencyNamed:ofType:)` properties can be fulfilled by `@Instantiated` or `@Received(fulfilledByDependencyNamed:ofType:)` properties declared on this type
+3. The type is not instantiated by another `@Instantiable` type
 
 ### Comparing SafeDI and Manual Injection: Key Differences
 

Sources/SafeDICore/Generators/DependencyTreeGenerator.swift

@@ -148,7 +148,7 @@ public final class DependencyTreeGenerator {
     private lazy var possibleRootInstantiableTypes: Set<TypeDescription> = Set(
         typeDescriptionToFulfillingInstantiableMap
             .values
-            .filter(\.dependencies.areAllInstantiated)
+            .filter(\.dependencies.couldRepresentRoot)
             .map(\.concreteInstantiableType)
     )
 
@@ -296,11 +296,17 @@ public final class DependencyTreeGenerator {
                 let parentContainsProperty = receivableProperties.contains(receivedProperty)
                 let propertyIsCreatedAtThisScope = createdProperties.contains(receivedProperty)
                 if !parentContainsProperty && !propertyIsCreatedAtThisScope {
-                    unfulfillableProperties.insert(.init(
-                        property: receivedProperty,
-                        instantiable: scope.instantiable,
-                        parentStack: instantiables.elements)
-                    )
+                    if instantiables.elements.isEmpty {
+                        // This property's scope is not a real root instantiable! Remove it from the list.
+                        rootInstantiableTypes.remove(scope.instantiable.concreteInstantiableType)
+                    } else {
+                        // This property is in a dependency tree and is unfulfillable. Record the problem.
+                        unfulfillableProperties.insert(.init(
+                            property: receivedProperty,
+                            instantiable: scope.instantiable,
+                            parentStack: instantiables.elements)
+                        )
+                    }
                 }
             }
 
@@ -357,26 +363,33 @@ extension Dependency {
     fileprivate var isInstantiated: Bool {
         switch source {
         case .instantiated:
-            return true
+            true
         case .aliased, .forwarded, .received:
-            return false
+            false
         }
     }
     fileprivate var isForwarded: Bool {
         switch source {
         case .forwarded:
-            return true
+            true
         case .aliased, .instantiated, .received:
-            return false
+            false
         }
     }
 }
 
-// MARK: - Array
+// MARK: - Collection
 
-extension Array where Element == Dependency {
-    fileprivate var areAllInstantiated: Bool {
-        first(where: { !$0.isInstantiated }) == nil
+extension Collection where Element == Dependency {
+    fileprivate var couldRepresentRoot: Bool {
+        first(where: {
+            switch $0.source {
+            case .instantiated, .aliased:
+                false
+            case .forwarded, .received:
+                true
+            }
+        }) == nil
     }
 }
 

Tests/SafeDIToolTests/SafeDIToolTests.swift

@@ -2295,6 +2295,107 @@ final class SafeDIToolTests: XCTestCase {
         )
     }
 
+    func test_run_writesConvenienceExtensionOnRootOfTree_whenRootHasReceivedAliasOfInstantiable() async throws {
+        let output = try await executeSystemUnderTest(
+            swiftFileContent: [
+                """
+                @Instantiable
+                public struct Root {
+                    @Instantiated
+                    private let defaultUserService: DefaultUserService
+
+                    @Received(fulfilledByDependencyNamed: "defaultUserService", ofType: DefaultUserService.self)
+                    private let userService: any UserService
+                }
+                """,
+                """
+                import Foundation
+
+                public protocol UserService {
+                    var userName: String? { get set }
+                }
+
+                @Instantiable(fulfillingAdditionalTypes: [UserService.self])
+                public final class DefaultUserService: UserService {
+                    public init() {}
+
+                    public var userName: String?
+                }
+                """,
+            ],
+            buildDependencyTreeOutput: true
+        )
+
+        XCTAssertEqual(
+            try XCTUnwrap(output.dependencyTree),
+            """
+            // This file was generated by the SafeDIGenerateDependencyTree build tool plugin.
+            // Any modifications made to this file will be overwritten on subsequent builds.
+            // Please refrain from editing this file directly.
+
+            #if canImport(Foundation)
+            import Foundation
+            #endif
+
+            extension Root {
+                public init() {
+                    let defaultUserService = DefaultUserService()
+                    let userService: any UserService = defaultUserService
+                    self.init(defaultUserService: defaultUserService, userService: userService)
+                }
+            }
+            """
+        )
+    }
+
+    func test_run_successfullyGeneratesOutputFileWhenNoRootFound() async throws {
+        let output = try await executeSystemUnderTest(
+            swiftFileContent: [
+                """
+                @Instantiable
+                public struct NotRoot {
+                    @Instantiated
+                    private let defaultUserService: DefaultUserService
+
+                    // This received property's alias is improperly configured, meaning that this type is not a root.
+                    @Received(fulfilledByDependencyNamed: "userService", ofType: DefaultUserService.self)
+                    private let userService: any UserService
+                }
+                """,
+                """
+                import Foundation
+
+                public protocol UserService {
+                    var userName: String? { get set }
+                }
+
+                @Instantiable(fulfillingAdditionalTypes: [UserService.self])
+                public final class DefaultUserService: UserService {
+                    public init() {}
+
+                    public var userName: String?
+                }
+                """,
+            ],
+            buildDependencyTreeOutput: true
+        )
+
+        XCTAssertEqual(
+            try XCTUnwrap(output.dependencyTree),
+            """
+            // This file was generated by the SafeDIGenerateDependencyTree build tool plugin.
+            // Any modifications made to this file will be overwritten on subsequent builds.
+            // Please refrain from editing this file directly.
+
+            #if canImport(Foundation)
+            import Foundation
+            #endif
+
+            // No root @Instantiable-decorated types found, or root types already had a `public init()` method.
+            """
+        )
+    }
+
     func test_run_writesConvenienceExtensionOnRootOfTree_whenReceivedPropertyIsAliased() async throws {
         let output = try await executeSystemUnderTest(
             swiftFileContent: [