Add unit test

Signed-off-by: Zhaohui Sun <zhaohuisun@microsoft.com>

tests/caclmgrd/caclmgrd_test.py

@@ -1,14 +1,14 @@
 import os
 import sys
 import swsscommon
-from unittest.mock import call
+from unittest.mock import call, patch
 from unittest import TestCase, mock
 from tests.common.mock_configdb import MockConfigDb
 from sonic_py_common.general import load_module_from_source
 import threading
 import time
 import sys
-import traceback
+
 from queue import Queue
 class TestCaclmgrd(TestCase):
     def setUp(self):
@@ -34,3 +34,21 @@ def test_get_chain_list(self):
         with mock.patch("caclmgrd.ControlPlaneAclManager.run_commands_pipe") as mock_run_commands_pipe:
             caclmgrd_daemon.get_chain_list([], [''])
             mock_run_commands_pipe.assert_has_calls(expected_calls)
+
+    @patch('caclmgrd.ControlPlaneAclManager.update_control_plane_acls')
+    def test_update_control_plane_acls_exception(self, mock_update):
+        # Set the side effect to raise an exception
+        mock_update.side_effect = Exception('Test exception')
+        # Mock the necessary attributes and methods
+        manager = self.caclmgrd.ControlPlaneAclManager("caclmgrd")
+        manager.UPDATE_DELAY_SECS = 1
+        manager.lock = {'': threading.Lock()}
+        manager.num_changes = {'': 0}
+        manager.update_thread = {'': None}
+        exception_queue = Queue()
+        manager.num_changes[''] = 1
+        manager.check_and_update_control_plane_acls('', 0, exception_queue)
+        self.assertFalse(exception_queue.empty())
+        exc_info = exception_queue.get()
+        self.assertEqual(exc_info[0], '')
+        self.assertIn('Test exception', exc_info[1])