code: def setUpClass(cls):
      cls.handler = SlackHandler("test-slack-token")
  
imports: from mindsdb.integrations.handlers.slack_handler import SlackHandler
  import unittest
  from unittest.mock import patch
label_desc: Use image node_id 1 for calling the SlackHandlerTest obj's underlying member method code with example usage: obj.setUpClass(cls) without return types