code: def _run_test(test_name, dtype=None):
      # subprocess is required not to interfere with cupy module imported in top
      # of this file
      runner_path = pathlib.Path(__file__).parent / "comm_runner.py"
      args = [sys.executable, runner_path, test_name, "store"]
      if dtype is not None:
          args.append(numpy.dtype(dtype).char)
      proc = subprocess.Popen(
          args, stdout=subprocess.PIPE, stderr=subprocess.PIPE
      )
      stdoutdata, stderrdata = proc.communicate()
      assert stderrdata.decode() == ""
      assert proc.returncode == 0
  
imports: import pathlib
  import subprocess
  import sys
  import unittest
  import os
  import numpy
  import pytest
  from cupy.cuda import nccl
  from cupy import testing
  from cupyx.distributed import init_process_group
  from cupyx.distributed._nccl_comm import _mpi_available
label_desc: Use image node_id 1 for calling a global function with example usage: _run_test(test_name, dtype) without return types