fix: make MockOneSignalClient hold/release atomic

Hold check and enqueue share one lock, and releaseHeldResponses clears the hold flag so in-flight test callbacks cannot be stranded.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalCoreMocks/MockOneSignalClient.swift

@@ -102,14 +102,16 @@ public class MockOneSignalClient: NSObject, IOneSignalClient {
     public func execute(_ request: OneSignalRequest, onSuccess successBlock: @escaping OSResultSuccessBlock, onFailure failureBlock: @escaping OSClientFailureBlock) {
         print("🧪 MockOneSignalClient execute called")
 
-        lock.withLock {
+        // Check hold + enqueue under one lock so releaseHeldResponses can't miss a callback mid-hold.
+        let shouldHold = lock.withLock { () -> Bool in
             startedRequests.append(request)
-        }
-
-        if holdResponses {
-            lock.withLock {
-                heldExecutions.append((request, successBlock, failureBlock))
+            guard holdResponses else {
+                return false
             }
+            heldExecutions.append((request, successBlock, failureBlock))
+            return true
+        }
+        if shouldHold {
             return
         }
 
@@ -122,9 +124,10 @@ public class MockOneSignalClient: NSObject, IOneSignalClient {
         }
     }
 
-    /// Completes every request currently held by `holdResponses`.
+    /// Completes every request currently held by `holdResponses`, and stops holding further executes.
     public func releaseHeldResponses() {
         let held: [(request: OneSignalRequest, onSuccess: OSResultSuccessBlock, onFailure: OSClientFailureBlock)] = lock.withLock {
+            holdResponses = false
             let copy = heldExecutions
             heldExecutions.removeAll()
             return copy

iOS_SDK/OneSignalSDK/OneSignalUserTests/Executors/SubscriptionUpdateRaceTests.swift

@@ -180,7 +180,6 @@ final class SubscriptionUpdateRaceTests: XCTestCase {
 
         XCTAssertEqual(client.startedRequests.count, 1, "Follow-up must wait for in-flight UpdateSubscription")
 
-        client.holdResponses = false
         client.releaseHeldResponses()
         OneSignalCoreMocks.waitForBackgroundThreads(seconds: 0.5)