Field Merging [5/x] Move fieldMerging option to experimental

Tests/ApolloCodegenInternalTestHelpers/MockApolloCodegenConfiguration.swift

@@ -30,6 +30,7 @@ extension ApolloCodegenConfiguration {
   public static func mock(
     _ moduleType: ApolloCodegenConfiguration.SchemaTypesFileOutput.ModuleType,
     options: ApolloCodegenConfiguration.OutputOptions = .init(),
+    experimentalFeatures: ExperimentalFeatures = .init(),
     schemaNamespace: String = "TestSchema",
     to path: String = "MockModulePath"
   ) -> Self {
@@ -42,7 +43,8 @@ extension ApolloCodegenConfiguration {
       output: .init(
         schemaTypes: .init(path: path, moduleType: moduleType)
       ),
-      options: options
+      options: options,
+      experimentalFeatures: experimentalFeatures
     )
   }
 }

Tests/ApolloCodegenTests/ApolloCodegenConfigurationCodableTests.swift

@@ -67,6 +67,7 @@ class ApolloCodegenConfigurationCodableTests: XCTestCase {
           markOperationDefinitionsAsFinal: true
         ),
         experimentalFeatures: .init(
+          fieldMerging: .all,
           legacySafelistingCompatibleOperations: true
         ),
         operationManifest: .init(
@@ -81,6 +82,9 @@ class ApolloCodegenConfigurationCodableTests: XCTestCase {
       """
       {
         "experimentalFeatures" : {
+          "fieldMerging" : [
+            "all"
+          ],
           "legacySafelistingCompatibleOperations" : true
         },
         "input" : {
@@ -112,9 +116,6 @@ class ApolloCodegenConfigurationCodableTests: XCTestCase {
             "inputObjects" : "none"
           },
           "deprecatedEnumCases" : "exclude",
-          "fieldMerging" : [
-            "all"
-          ],
           "markOperationDefinitionsAsFinal" : true,
           "operationDocumentFormat" : [
             "definition"

Tests/ApolloCodegenTests/ApolloCodegenTests.swift

@@ -2415,6 +2415,46 @@ class ApolloCodegenTests: XCTestCase {
     })
   }
 
+  func test__validation__givenFieldMerging_notAll_andSelectionSetInitializers_enabled_shouldThrowError() throws {
+    // given
+    let fieldMergingOptions: [ApolloCodegenConfiguration.FieldMerging] = [
+      .none,
+      .ancestors,
+      .namedFragments,
+      .siblings,
+      [.ancestors, .namedFragments],
+      [.siblings, .ancestors],
+      [.siblings, .namedFragments]
+    ]
+    let initializerOptions: [ApolloCodegenConfiguration.SelectionSetInitializers] = [
+      .all,
+      .localCacheMutations,
+      .operations,
+      .namedFragments,
+      .fragment(named: "TestFragment"),
+      [.operations, .localCacheMutations]
+    ]
+
+    for fieldMergingOption in fieldMergingOptions {
+      for initializerOption in initializerOptions {
+
+        let config = ApolloCodegenConfiguration.mock(
+          .other,
+          options: .init(
+            selectionSetInitializers: initializerOption
+          ),
+          experimentalFeatures: .init(
+            fieldMerging: fieldMergingOption
+          )
+        )
+
+        // then
+        expect(try ApolloCodegen._validate(config: config))
+          .to(throwError(ApolloCodegen.Error.fieldMergingIncompatibility))
+      }
+    }
+  }
+
   // MARK: Path Match Exclusion Tests
 
   func test__match__givenFilesInSpecialExcludedPaths_shouldNotReturnExcludedPaths() throws {

Tests/ApolloCodegenTests/CodeGeneration/Templates/FragmentTemplateTests.swift

@@ -653,9 +653,9 @@ class FragmentTemplateTests: XCTestCase {
       // when
       try await buildSubjectAndFragment(config: .mock(
         options: .init(
-          selectionSetInitializers: [.all],
-          fieldMerging: test
-        )
+          selectionSetInitializers: [.all]
+        ),
+        experimentalFeatures: .init(fieldMerging: test)
       ))
 
       let actual = renderSubject()

Tests/ApolloCodegenTests/CodeGeneration/Templates/OperationDefinitionTemplateTests.swift

@@ -669,9 +669,9 @@ class OperationDefinitionTemplateTests: XCTestCase {
 
       config = .mock(
         options: .init(
-          selectionSetInitializers: [.all],
-          fieldMerging: test
-        )
+          selectionSetInitializers: [.all]
+        ),
+        experimentalFeatures: .init(fieldMerging: test)
       )
 
       // when

Tests/ApolloCodegenTests/CodeGeneration/Templates/SelectionSet/SelectionSetTemplate_ErrorHandling_Tests.swift

@@ -44,7 +44,7 @@ class SelectionSetTemplate_ErrorHandling_Tests: XCTestCase {
     let config = ApolloCodegenConfiguration.mock(
       schemaNamespace: "TestSchema",
       output: .mock(moduleType: .swiftPackageManager, operations: .inSchemaModule),
-      options: .init(
+      experimentalFeatures: .init(
         fieldMerging: fieldMerging
       )
     )

Tests/ApolloCodegenTests/CodeGeneration/Templates/SelectionSet/SelectionSetTemplate_FieldMerging_Tests.swift

@@ -52,11 +52,11 @@ class SelectionSetTemplate_FieldMerging_Tests: XCTestCase {
       options: .init(
         additionalInflectionRules: inflectionRules,
         schemaDocumentation: schemaDocumentation,
-        fieldMerging: fieldMerging,
         cocoapodsCompatibleImportStatements: cocoapodsImportStatements,
         warningsOnDeprecatedUsage: warningsOnDeprecatedUsage,
         conversionStrategies: conversionStrategies
-      )
+      ),
+      experimentalFeatures: .init(fieldMerging: fieldMerging)
     ))
     let mockTemplateRenderer = MockTemplateRenderer(
       target: .operationFile(),
@@ -1218,4 +1218,82 @@ class SelectionSetTemplate_FieldMerging_Tests: XCTestCase {
     expect(actual).to(equalLineByLine(expected, atLine: 12, ignoringExtraLines: true))
   }
 
+  // MARK: - SelectionSetInitializers
+
+  func test__render_selectionSetInitializer__givenFieldMerging_none_withMergedSelections_rendersInitializerWithAllMergedSelections() async throws {
+    // given
+    schemaSDL = """
+    type Query {
+      allAnimals: [Animal!]
+    }
+
+    interface Animal {
+      species: String!
+      age: Int!
+    }
+
+    interface Pet implements Animal {
+      species: String!
+      age: Int!
+    }
+
+    type Dog implements Animal & Pet {
+      species: String!
+      age: Int!
+      bark: Boolean!
+    }
+    """
+
+    document = """
+    query TestOperation {
+      allAnimals {
+        age
+        ... on Pet {
+          species
+        }
+        ... on Dog {
+          bark
+        }
+      }
+    }
+    """
+
+    let expected =
+    """
+      public init(
+        bark: Bool,
+        age: Int,
+        species: String
+      ) {
+        self.init(_dataDict: DataDict(
+          data: [
+            "__typename": TestSchema.Objects.Dog.typename,
+            "bark": bark,
+            "age": age,
+            "species": species,
+          ],
+          fulfilledFragments: [
+            ObjectIdentifier(TestOperationQuery.Data.AllAnimal.self),
+            ObjectIdentifier(TestOperationQuery.Data.AllAnimal.AsDog.self),
+            ObjectIdentifier(TestOperationQuery.Data.AllAnimal.AsPet.self)
+          ]
+        ))
+      }
+    """
+
+    // when
+    try await buildSubjectAndOperation(
+      fieldMerging: .none,
+      selectionSetInitializers: true
+    )
+
+    let allAnimals_asDog = try XCTUnwrap(
+      operation[field: "query"]?[field: "allAnimals"]?[as: "Dog"]
+    )
+
+    let actual = subject.test_render(childEntity: allAnimals_asDog.computed)
+
+    // then
+    expect(actual).to(equalLineByLine(expected, atLine: 14, ignoringExtraLines: true))
+  }
 }

apollo-ios-codegen/Sources/ApolloCodegenLib/ApolloCodegen+Errors.swift

@@ -17,6 +17,7 @@ extension ApolloCodegen {
     case invalidConfiguration(message: String)
     case invalidSchemaName(_ name: String, message: String)
     case targetNameConflict(name: String)
+    case fieldMergingIncompatibility
 
     public var errorDescription: String? {
       switch self {
@@ -52,6 +53,13 @@ extension ApolloCodegen {
           Target name '\(name)' conflicts with a reserved library name. Please choose a different \
           target name.
           """
+      case .fieldMergingIncompatibility:
+        return """
+          Options for disabling 'fieldMerging' and enabling 'selectionSetInitializers' are
+          incompatible.
+
+          Please set either 'fieldMerging' to 'all' or 'selectionSetInitializers' to be empty.
+          """
       }
     }
   }