code: def test_call(self):
      target = mock.MagicMock()
      w = snapshot_writers.StandardWriter()
      worker = mock.MagicMock()
      name = snapshot_writers_path + ".StandardWriter.create_worker"
      with mock.patch(name, return_value=worker):
          with utils.tempdir() as tempd:
              w("myfile.dat", tempd, target)
              w("myfile.dat", tempd, target)
              w.finalize()
  
          assert worker.start.call_count == 2
          assert worker.join.call_count == 2
  
imports: import multiprocessing
  import threading
  import unittest
  import mock
  from chainer import testing
  from chainer.training.extensions import snapshot_writers
  from chainer import utils
label_desc: Use image node_id 1 for calling the TestStandardWriter obj's underlying member method code with example usage: obj.test_call() without return types