Return copied CKRecords when modifying database.

Sources/SQLiteData/CloudKit/Internal/MockCloudContainer.swift

@@ -52,7 +52,8 @@
       let rootRecord: CKRecord? = database.state.withValue {
         $0.storage[share.recordID.zoneID]?.records.values.first { record in
           record.share?.recordID == share.recordID
-        }
+        }?
+          .copy() as? CKRecord
       }
 
       return ShareMetadata(

Sources/SQLiteData/CloudKit/Internal/MockCloudDatabase.swift

@@ -188,21 +188,22 @@
                 return
               }
 
-              guard let copy = recordToSave.copy() as? CKRecord
+              guard let databaseCopy = recordToSave.copy() as? CKRecord
               else { fatalError("Could not copy CKRecord.") }
-              copy._recordChangeTag = state.nextRecordChangeTag()
+              databaseCopy._recordChangeTag = state.nextRecordChangeTag()
 
-              for key in copy.allKeys() {
-                guard let assetURL = (copy[key] as? CKAsset)?.fileURL
+              for key in databaseCopy.allKeys() {
+                guard let assetURL = (databaseCopy[key] as? CKAsset)?.fileURL
                 else { continue }
-                state.assets[AssetID(recordID: copy.recordID, key: key)] =
+                state.assets[AssetID(recordID: databaseCopy.recordID, key: key)] =
                   try? dataManager.wrappedValue
                   .load(assetURL)
               }
 
               // TODO: This should merge copy's values to more accurately reflect reality
-              state.storage[recordToSave.recordID.zoneID]?.records[recordToSave.recordID] = copy
-              saveResults[recordToSave.recordID] = .success(copy)
+              state.storage[recordToSave.recordID.zoneID]?.records[recordToSave.recordID] =
+                databaseCopy
+              saveResults[recordToSave.recordID] = .success(databaseCopy.copy() as! CKRecord)
 
               // NB: "Touch" parent records when saving a child:
               if let parent = recordToSave.parent,

Sources/SQLiteData/CloudKit/Internal/MockSyncEngine.swift

@@ -49,6 +49,7 @@
           accum,
           zoneID in
           accum += ((state.storage[zoneID]?.records.values).map { Array($0) } ?? [])
+            .map { $0.copy() as! CKRecord }
             .filter {
               precondition(
                 $0._recordChangeTag != nil,

Tests/SQLiteDataTests/CloudKitTests/AppLifecycleTests.swift

@@ -5,6 +5,7 @@
   import InlineSnapshotTesting
   import SQLiteData
   import SnapshotTestingCustomDump
+  import TestLocals
   import Testing
   import SQLiteDataTestSupport
 
@@ -24,7 +25,9 @@
           }
         }
         defaultNotificationCenter.post(
-          name: UIApplication.willResignActiveNotification, object: nil)
+          name: UIApplication.willResignActiveNotification,
+          object: nil
+        )
         try await Task.sleep(for: .seconds(1))
         assertInlineSnapshot(of: container, as: .customDump) {
           """
@@ -52,10 +55,12 @@
       }
 
       @available(iOS 17, macOS 14, tvOS 17, watchOS 10, *)
-      @Test(.startImmediately(false))
+      @Test(.taskLocal($startImmediately, false))
       func background_whileNotRunning() async throws {
         defaultNotificationCenter.post(
-          name: UIApplication.willResignActiveNotification, object: nil)
+          name: UIApplication.willResignActiveNotification,
+          object: nil
+        )
         try await Task.sleep(for: .seconds(1))
         // NB: Not runtime warnings emitted.
       }
@@ -101,7 +106,9 @@
         }
 
         defaultNotificationCenter.post(
-          name: UIApplication.willResignActiveNotification, object: nil)
+          name: UIApplication.willResignActiveNotification,
+          object: nil
+        )
         try await Task.sleep(for: .seconds(1))
         assertInlineSnapshot(of: container, as: .customDump) {
           """

Tests/SQLiteDataTests/CloudKitTests/MockCloudDatabaseTests.swift

@@ -741,6 +741,49 @@
         }
         #expect(error?.code == .limitExceeded)
       }
+
+      @available(iOS 17, macOS 14, tvOS 17, watchOS 10, *)
+      @Test func `mutating record returned from modifyRecords does not mutate database`() async throws {
+        let record = CKRecord(recordType: "A", recordID: CKRecord.ID(recordName: "1"))
+        record["title"] = "original"
+        let (saveResults, _) = try syncEngine.private.database.modifyRecords(saving: [record])
+        let savedRecord = try #require(try saveResults[record.recordID]?.get())
+        savedRecord["title"] = "mutated"
+
+        let storedRecord = try syncEngine.private.database.record(for: record.recordID)
+        #expect(storedRecord["title"] as? String == "original")
+      }
+
+      @available(iOS 17, macOS 14, tvOS 17, watchOS 10, *)
+      @Test func `mutating record returned from non-atomic modifyRecords does not mutate database`() async throws {
+        let record = CKRecord(recordType: "A", recordID: CKRecord.ID(recordName: "1"))
+        record["title"] = "original"
+        let (saveResults, _) = try syncEngine.private.database.modifyRecords(
+          saving: [record],
+          atomically: false
+        )
+        let savedRecord = try #require(try saveResults[record.recordID]?.get())
+        savedRecord["title"] = "mutated"
+
+        let storedRecord = try syncEngine.private.database.record(for: record.recordID)
+        #expect(storedRecord["title"] as? String == "original")
+      }
+
+      @available(iOS 17, macOS 14, tvOS 17, watchOS 10, *)
+      @Test func `mutating record returned from shareMetadata does not mutate database`() async throws {
+        let record = CKRecord(recordType: "A", recordID: CKRecord.ID(recordName: "1"))
+        record["title"] = "original"
+        let share = CKShare(rootRecord: record, shareID: CKRecord.ID(recordName: "share"))
+        _ = try syncEngine.private.database.modifyRecords(saving: [share, record])
+
+        let metadata = try await container.shareMetadata(for: share, shouldFetchRootRecord: true)
+        let rootRecord = try #require(metadata.rootRecord)
+        rootRecord["title"] = "mutated"
+
+        let storedRecord = try syncEngine.private.database.record(for: record.recordID)
+        #expect(storedRecord["title"] as? String == "original")
+      }
+
     }
   }
 #endif

Tests/SQLiteDataTests/CloudKitTests/MockSyncEngineTests.swift

@@ -0,0 +1,44 @@
+#if canImport(CloudKit)
+  import CloudKit
+  import Dependencies
+  import SQLiteData
+  import Testing
+
+  extension BaseCloudKitTests {
+    @MainActor
+    final class MockSyncEngineTests: BaseCloudKitTests, @unchecked Sendable {
+      @available(iOS 17, macOS 14, tvOS 17, watchOS 10, *)
+      @Test func `fetching changes does not mutate database`() async throws {
+        try await userDatabase.userWrite { db in
+          try db.seed {
+            RemindersList(id: 1, title: "Personal")
+          }
+        }
+        try await syncEngine.processPendingRecordZoneChanges(scope: .private)
+
+        try await withDependencies {
+          $0.currentTime.now += 30
+        } operation: {
+          try await userDatabase.userWrite { db in
+            try RemindersList.find(1).update { $0.title = "Family" }.execute(db)
+          }
+        }
+
+        let before = try syncEngine.private.database.record(
+          for: RemindersList.recordID(for: 1)
+        )
+        #expect(before.userModificationTime == 0)
+
+        try await syncEngine.private.fetchChanges(CKSyncEngine.FetchChangesOptions())
+
+        let after = try syncEngine.private.database.record(
+          for: RemindersList.recordID(for: 1)
+        )
+        #expect(after.userModificationTime == 0)
+        #expect(after.encryptedValues["title"] as? String == "Personal")
+
+        try await syncEngine.processPendingRecordZoneChanges(scope: .private)
+      }
+    }
+  }
+#endif