old_contents: import io
  import os
  import tempfile
  import unittest
  
  import mock
  
  from chainer import datasets
  from chainer import testing
  
  
  class TestPickleDataset(unittest.TestCase):
  
      def setUp(self):
          self.io = io.BytesIO()
  
      def test_write_read(self):
          writer = datasets.PickleDatasetWriter(self.io)
          writer.write(1)
          writer.write('hello')
          writer.write(1.5)
          writer.flush()
  
          dataset = datasets.PickleDataset(self.io)
          assert len(dataset) == 3
          assert dataset[0] == 1
          assert dataset[2] == 1.5
          assert dataset[1] == 'hello'
  
  
  class TestPickleDatasetHelper(unittest.TestCase):
  
      def setUp(self):
          _, self.path = tempfile.mkstemp()
  
      def tearDown(self):
          if os.path.exists(self.path):
              os.remove(self.path)
  
      def test_write_read(self):
          with datasets.open_pickle_dataset_writer(self.path) as writer:
              writer.write(1)
  
          with datasets.open_pickle_dataset(self.path) as dataset:
              assert dataset[0] == 1
  
      def test_dataset_init_fail(self):
          m = mock.mock_open(read_data=b'dummy')
          with mock.patch('chainer.datasets.pickle_dataset.open', m):
              try:
                  datasets.open_pickle_dataset(self.path)
              except Exception:
                  # This dummy data causes an error in initializer
                  pass
          # Even in this situation, the opened file needs to be closed
          assert mock.call().close() in m.mock_calls
  
  
  testing.run_module(__name__, __file__)
  
new_contents: import io
  import os
  import tempfile
  import unittest
  
  import mock
  
  from chainer import datasets
  from chainer import testing
  
  
  class TestPickleDataset(unittest.TestCase):
  
      def setUp(self):
          self.io = io.BytesIO()
  
      def test_write_read(self):
          writer = datasets.PickleDatasetWriter(self.io)
          writer.write(1)
          writer.write('hello')
          writer.write(1.5)
          writer.flush()
  
          dataset = datasets.PickleDataset(self.io)
          assert len(dataset) == 3
          assert dataset[0] == 1
          assert dataset[2] == 1.5
          assert dataset[1] == 'hello'
  
  
  class TestPickleDatasetHelper(unittest.TestCase):
  
      def setUp(self):
          _, self.path = tempfile.mkstemp()
  
      def tearDown(self):
          if os.path.exists(self.path):
              os.remove(self.path)
  
      def test_write_read(self):
          with datasets.open_pickle_dataset_writer(self.path) as writer:
              writer.write(1)
  
          with datasets.open_pickle_dataset(self.path) as dataset:
              assert dataset[0] == 1
  
  
  testing.run_module(__name__, __file__)
  
subject: Remove test