flaky test due to not waiting for OperationRepo

This test had two problems:
1. We were not waiting for OperationRepo.loadSavedOperations to finish
2. After we added waiting, it didn't work we didn't wrap
RecoverFromDroppedLoginBug in spyk(). This was causing all fields
and properties being cleared from it!

Author: jkasten2

OneSignalSDK/onesignal/core/src/test/java/com/onesignal/user/internal/migrations/RecoverFromDroppedLoginBugTests.kt

@@ -1,6 +1,8 @@
 package com.onesignal.user.internal.migrations
 
+import com.onesignal.common.threading.Waiter
 import com.onesignal.core.internal.config.ConfigModelStore
+import com.onesignal.core.internal.operations.IOperationRepoLoadedListener
 import com.onesignal.core.internal.operations.impl.OperationModelStore
 import com.onesignal.core.internal.operations.impl.OperationRepo
 import com.onesignal.core.internal.time.impl.Time
@@ -31,16 +33,24 @@ class RecoverFromDroppedLoginBugTests : FunSpec({
             )
         every { mockOperationModelStore.loadOperations() } just runs
         every { mockOperationModelStore.list() } returns listOf()
-
-        val recovery = RecoverFromDroppedLoginBug(operationRepo, MockHelper.identityModelStore(), mockConfigModelStore)
-        every { recovery.onOperationRepoLoaded() } just runs
+        val recovery = spyk(RecoverFromDroppedLoginBug(operationRepo, MockHelper.identityModelStore(), mockConfigModelStore))
 
         // When
-        operationRepo.start()
         recovery.start()
+        val waiter = Waiter()
+        operationRepo.addOperationLoadedListener(
+            object : IOperationRepoLoadedListener {
+                override fun onOperationRepoLoaded() {
+                    waiter.wake()
+                }
+            },
+        )
+        operationRepo.start()
+        // Waiting here ensures recovery.onOperationRepoLoaded() is called consistently
+        waiter.waitForWake()
 
         // Then
-        verify {
+        verify(exactly = 1) {
             operationRepo.subscribe(recovery)
             recovery.onOperationRepoLoaded()
         }