code: def test_request_job(self):
      worker_manager = WorkerManager("localhost", ["gpu"])
      job1 = worker_manager.request_job(n_cpu=0, n_gpu=2)
      self.assertTrue(job1 is None)
  
      worker_manager.add_worker(self.worker1)
      job2 = worker_manager.request_job(n_cpu=0, n_gpu=2)
      self.assertTrue(job2 in self.worker1.initialized_jobs)
      self.assertEqual(worker_manager.job_num, 3)
      self.assertEqual(worker_manager.gpu_num, 2)
  
      job3 = worker_manager.request_job(n_cpu=0, n_gpu=4)
      self.assertTrue(job3 is None)
  
      worker_manager.add_worker(self.worker2)
      job4 = worker_manager.request_job(n_cpu=0, n_gpu=8)
      self.assertTrue(job4 is None)
  
      worker_manager.add_worker(self.worker5)
      job5 = worker_manager.request_job(n_cpu=0, n_gpu=9)
      self.assertTrue(job5 is None)
  
file_path: PARL/parl/remote/tests/gpu/worker_manager_test.py
imports: import unittest
  import socket
  from parl.remote.worker_manager import WorkerManager
  from parl.remote.message import InitializedWorker, InitializedJob, AllocatedCpu, AllocatedGpu
  from parl.utils.test_utils import XparlTestCase
label_desc: Use image node_id 4 for calling the ImportTest obj's underlying member method code with example usage: obj.test_request_job() without return types