code: def test_cpu_worker_connect_gpu_master(self):
      master = Master(port=self.port, device="gpu")
      th = threading.Thread(target=master.run)
      th.start()
      time.sleep(10)
      self.add_worker(n_cpu=1, gpu="")
      self.assertEqual(master.gpu_num, 0)
      self.assertEqual(master.cpu_num, 0)
  
      master.exit()
  
file_path: PARL/parl/remote/tests/gpu/worker_test.py
imports: import unittest
  import parl
  from parl.remote.master import Master
  from parl.remote.worker import Worker
  import time
  import threading
  from parl.remote.client import disconnect
  from parl.utils import logger, get_free_tcp_port
  from parl.utils.test_utils import XparlTestCase
label_desc: Use image node_id 2 for calling the TestCluster obj's underlying member method code with example usage: obj.test_cpu_worker_connect_gpu_master() without return types