Fix duplicate outcome validation during sync

CareKit/CareKitTests/Synchronization/TestOutcomeDuplicate.swift

@@ -0,0 +1,74 @@
+/*
+ Copyright (c) 2016-2025, Apple Inc. All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without modification,
+ are permitted provided that the following conditions are met:
+
+ 1.  Redistributions of source code must retain the above copyright notice, this
+ list of conditions and the following disclaimer.
+
+ 2.  Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions and the following disclaimer in the documentation and/or
+ other materials provided with the distribution.
+
+ 3. Neither the name of the copyright holder(s) nor the names of any contributors
+ may be used to endorse or promote products derived from this software without
+ specific prior written permission. No license is granted to the trademarks of
+ the copyright holders even if such marks are included in this software.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import XCTest
+@testable import CareKitStore
+import CoreData
+
+class TestOutcomeDuplicate: XCTestCase {
+    var context: NSManagedObjectContext!
+
+    override func setUp() {
+        super.setUp()
+        context = OCKCoreDataContextFactory().makeContext()
+    }
+
+    func testDuplicateOutcomeValidation() throws {
+        // Create a task 
+        let task = OCKCDTask(context: context)
+        task.uuid = UUID()
+        task.scheduleElements = []
+
+        // Create first outcome 
+        let outcome1 = OCKCDOutcome(context: context)
+        outcome1.uuid = UUID()
+        outcome1.task = task
+        outcome1.taskOccurrenceIndex = 0
+
+        // Create a next version outcome 
+        let outcome2 = OCKCDOutcome(context: context)
+        outcome2.uuid = UUID()
+        outcome2.task = task 
+        outcome2.taskOccurrenceIndex = 0
+        outcome1.next = [outcome2]
+
+        // outcome1 should skip duplicate validation because it has a next version
+        XCTAssertNoThrow(try outcome1.validateForInsert())
+
+        // Save outcome1 to context
+        try context.save()
+
+        // outcome2 should check for duplicates and throw, since outcome1 exists
+        outcome2.next = []
+        XCTAssertThrowsError(try outcome2.validateForInsert()) { error in 
+            XCTAssertEqual((error as? OCKStoreError)?.localizedDescription, "A duplicate outcome exists for this task.")
+        }
+    }
+}

CareKitStore/CareKitStore/CoreData/OCKCDOutcome.swift

@@ -86,6 +86,11 @@ class OCKCDOutcome: OCKCDVersionedObject {
             return
         }
 
+        // Fix: If this outcome has a next version, skip duplicate validation.
+        if next.count > 0 {
+            return
+        }
+
         let request = NSFetchRequest<OCKCDObject>(entityName: entity.name!)
 
         request.predicate = NSPredicate(