code: def setUp(self):
      self.mpi_comm = mpi4py.MPI.COMM_WORLD
      self.communicator = NodeAwareNaiveCommunicator(self.mpi_comm)
  
file_path: chainer/tests/chainermn_tests/communicator_tests/test_node_aware_communicator_base.py
imports: import collections
  import os
  import unittest
  import mpi4py.MPI
  import pytest
  from chainermn.communicators.mpi_communicator_base import MpiCommunicatorBase
label_desc: Use image node_id 1 for calling the TestMpiCommunicatorBase obj's underlying member method code with example usage: obj.setUp() without return types