fix: Deferred fragment accessor with nested fragment (#709)

Author: calvincestari

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

@@ -3822,7 +3822,93 @@ class SelectionSetTemplateTests: XCTestCase {
       ignoringExtraLines: true
     ))
   }
-  
+
+  func test__render_selections__givenDeferredNamedFragment_insideNamedFragment_rendersInitializerForBothMergedAndDirectFragmentAccessors() async throws {
+    // given
+    schemaSDL = """
+      type Query {
+        allAnimals: [Animal!]
+      }
+
+      type Animal {
+        id: String!
+        name: String!
+        species: String!
+      }
+      """.appendingDeferDirective()
+
+    document = """
+      query TestOperation {
+        allAnimals {
+          ...BasicFragment
+        }
+      }
+
+      fragment BasicFragment on Animal {
+        id
+        ...DetailsFragment @defer(label: "slowDetails")
+      }
+      
+      fragment DetailsFragment on Animal {
+        name
+        species
+      }
+      """
+
+    // when
+    try await buildSubjectAndOperation()
+
+    // then
+    let allAnimals = try XCTUnwrap(operation[field: "query"]?[field: "allAnimals"]?.selectionSet)
+    let allAnimals_basicFragment = try XCTUnwrap(allAnimals[fragment: "BasicFragment"])
+
+    let rendered_allAnimals = subject.test_render(childEntity: allAnimals.computed)
+
+    let basicFragmentSubject = SelectionSetTemplate(
+      definition: allAnimals_basicFragment.fragment,
+      generateInitializers: false,
+      config: self.subject.config,
+      nonFatalErrorRecorder: .init(),
+      renderAccessControl: self.subject.renderAccessControl()
+    )
+    let rendered_allAnimals_basicFragment = basicFragmentSubject.test_render(
+      childEntity: try XCTUnwrap(allAnimals_basicFragment.rootField.selectionSet?.computed)
+    )
+
+    expect(rendered_allAnimals).to(equalLineByLine(
+      """
+        public struct Fragments: FragmentContainer {
+          public let __data: DataDict
+          public init(_dataDict: DataDict) {
+            __data = _dataDict
+            _detailsFragment = Deferred(_dataDict: _dataDict)
+          }
+
+          public var basicFragment: BasicFragment { _toFragment() }
+          @Deferred public var detailsFragment: DetailsFragment?
+        }
+      """,
+      atLine: 14,
+      ignoringExtraLines: true
+    ))
+
+    expect(rendered_allAnimals_basicFragment).to(equalLineByLine(
+      """
+        public struct Fragments: FragmentContainer {
+          public let __data: DataDict
+          public init(_dataDict: DataDict) {
+            __data = _dataDict
+            _detailsFragment = Deferred(_dataDict: _dataDict)
+          }
+
+          @Deferred public var detailsFragment: DetailsFragment?
+        }
+      """,
+      atLine: 15,
+      ignoringExtraLines: true
+    ))
+  }
+
   func test__render_selections__givenDeferredInlineFragmentOnDifferentTypeCase_insideNamedFragment_rendersDeferredFragmentSelection() async throws {
     // given
     schemaSDL = """

apollo-ios-codegen/Sources/ApolloCodegenLib/Templates/SelectionSetTemplate.swift

@@ -526,12 +526,18 @@ struct SelectionSetTemplate {
   private func FragmentInitializerTemplate(
     _ selectionSet: ComputedSelectionSet
   ) -> String {
-    if let directSelections = selectionSet.direct,
-      (directSelections.inlineFragments.containsDeferredFragment
-      || directSelections.namedFragments.containsDeferredFragment)
-    {
-      return DesignatedInitializerTemplate(
-        """
+    guard
+      selectionSet.direct?.inlineFragments.containsDeferredFragment ?? false ||
+      selectionSet.direct?.namedFragments.containsDeferredFragment ?? false ||
+      selectionSet.merged.inlineFragments.containsDeferredFragment ||
+      selectionSet.merged.namedFragments.containsDeferredFragment
+    else {
+      return DesignatedInitializerTemplate()
+    }
+
+    return DesignatedInitializerTemplate(
+      """
+      \(ifLet: selectionSet.direct, { directSelections in """
         \(forEachIn: directSelections.inlineFragments.values, separator: "\n", {
           if let deferCondition = $0.typeInfo.deferCondition {
             return DeferredPropertyInitializationStatement(deferCondition.label)
@@ -546,12 +552,16 @@ struct SelectionSetTemplate {
 
           return ""
         })
-        """
-      )
+        """})
+      \(forEachIn: selectionSet.merged.namedFragments.values, separator: "\n", {
+        if let _ = $0.typeInfo.deferCondition {
+          return DeferredPropertyInitializationStatement($0.definition.name.firstLowercased)
+        }
 
-    } else {
-      return DesignatedInitializerTemplate()
-    }
+        return ""
+      })
+      """
+    )
   }
 
   private func DeferredPropertyInitializationStatement(_ propertyName: String) -> TemplateString {