Add comprehensive tests for scheduled task repository, scheduler service, and task handlers

- Implemented tests for ScheduledTaskRepository covering task creation, retrieval, filtering, and status updates.
- Developed tests for SchedulerService including task creation, cancellation, user task retrieval, and maintenance jobs.
- Created tests for TaskHandlerRegistry to validate task execution for various types, including credit recharge and sound playback.
- Ensured proper error handling and edge cases in task execution scenarios.
- Added fixtures and mocks to facilitate isolated testing of services and repositories.

check_tasks.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+"""Check current tasks in the database."""
+
+import asyncio
+from datetime import datetime
+
+from app.core.database import get_session_factory
+from app.repositories.scheduled_task import ScheduledTaskRepository
+
+async def check_tasks():
+    session_factory = get_session_factory()
+    
+    async with session_factory() as session:
+        repo = ScheduledTaskRepository(session)
+        
+        # Get all tasks
+        all_tasks = await repo.get_all(limit=20)
+        
+        print("All tasks in database:")
+        print("=" * 80)
+        for task in all_tasks:
+            print(f"ID: {task.id}")
+            print(f"Name: {task.name}")
+            print(f"Type: {task.task_type}")
+            print(f"Status: {task.status}")
+            print(f"Scheduled: {task.scheduled_at}")
+            print(f"Timezone: {task.timezone}")
+            print(f"Active: {task.is_active}")
+            print(f"User ID: {task.user_id}")
+            print(f"Executions: {task.executions_count}")
+            print(f"Last executed: {task.last_executed_at}")
+            print(f"Error: {task.error_message}")
+            print(f"Parameters: {task.parameters}")
+            print("-" * 40)
+        
+        # Check specifically for pending tasks
+        print(f"\nCurrent time: {datetime.utcnow()}")
+        print("\nPending tasks:")
+        from app.models.scheduled_task import TaskStatus
+        pending_tasks = await repo.get_all(limit=10)
+        pending_tasks = [t for t in pending_tasks if t.status == TaskStatus.PENDING and t.is_active]
+        
+        if not pending_tasks:
+            print("No pending tasks found")
+        else:
+            for task in pending_tasks:
+                time_diff = task.scheduled_at - datetime.utcnow()
+                print(f"- {task.name} (ID: {task.id}): scheduled for {task.scheduled_at} (in {time_diff})")
+
+if __name__ == "__main__":
+    asyncio.run(check_tasks())