old_contents: import unittest
  
  from chainer import testing
  from chainercv.dataset import PickableDataset
  
  
  class SampleDataset(PickableDataset):
      def __init__(self, len):
          super(SampleDataset, self).__init__()
  
          self.data_names = ('img', 'bbox', 'label', 'mask')
          self.add_getter('img', self.get_image)
          self.add_getter('mask', self.get_mask)
          self.add_getter(('bbox', 'label'), self.get_bbox_label)
  
          self.len = len
          self.count = 0
  
      def __len__(self):
          return self.len
  
      def get_image(self, i):
          self.count += 1
          return 'img_{:d}'.format(i)
  
      def get_mask(self, i):
          self.count += 1
          return 'mask_{:d}'.format(i)
  
      def get_bbox_label(self, i):
          self.count += 1
          return 'bbox_{:d}'.format(i), 'label_{:d}'.format(i)
  
  
  class TestAnnotatedImageDatasetMixin(unittest.TestCase):
  
      def setUp(self):
          self.len = 10
          self.dataset = SampleDataset(self.len)
  
      def test_base_dataset(self):
          self.assertEqual(len(self.dataset), self.len)
          self.assertEqual(
              self.dataset[0], ('img_0', 'bbox_0', 'label_0', 'mask_0'))
          self.assertEqual(self.dataset.count, 3)
  
      def test_single_picked_dataset(self):
          dataset = self.dataset.pick('label')
          self.assertEqual(len(dataset), self.len)
          self.assertEqual(dataset[1], 'label_1')
          self.assertEqual(self.dataset.count, 1)
  
      def test_multiple_picked_dataset(self):
          dataset = self.dataset.pick('label', 'bbox')
          self.assertEqual(len(dataset), self.len)
          self.assertEqual(dataset[2], ('label_2', 'bbox_2'))
          self.assertEqual(self.dataset.count, 1)
  
  
  testing.run_module(__name__, __file__)
  
new_contents: import unittest
  
  from chainer import testing
  from chainercv.dataset import PickableDataset
  
  
  class SampleDataset(PickableDataset):
      def __init__(self, len):
          super(SampleDataset, self).__init__()
  
          self.data_names = ('img', 'bbox', 'label', 'mask')
          self.add_getter('img', self.get_image)
          self.add_getter('mask', self.get_mask)
          self.add_getter(('bbox', 'label'), self.get_bbox_label)
  
          self.len = len
          self.count = 0
  
      def __len__(self):
          return self.len
  
      def get_image(self, i):
          self.count += 1
          return 'img_{:d}'.format(i)
  
      def get_mask(self, i):
          self.count += 1
          return 'mask_{:d}'.format(i)
  
      def get_bbox_label(self, i):
          self.count += 1
          return 'bbox_{:d}'.format(i), 'label_{:d}'.format(i)
  
  
  class TestPickableDataset(unittest.TestCase):
  
      def setUp(self):
          self.len = 10
          self.dataset = SampleDataset(self.len)
  
      def test_base_dataset(self):
          self.assertEqual(len(self.dataset), self.len)
          self.assertEqual(
              self.dataset[0], ('img_0', 'bbox_0', 'label_0', 'mask_0'))
          self.assertEqual(self.dataset.count, 3)
  
      def test_single_picked_dataset(self):
          dataset = self.dataset.pick('label')
          self.assertEqual(len(dataset), self.len)
          self.assertEqual(dataset[1], 'label_1')
          self.assertEqual(self.dataset.count, 1)
  
      def test_multiple_picked_dataset(self):
          dataset = self.dataset.pick('label', 'bbox')
          self.assertEqual(len(dataset), self.len)
          self.assertEqual(dataset[2], ('label_2', 'bbox_2'))
          self.assertEqual(self.dataset.count, 1)
  
  
  testing.run_module(__name__, __file__)
  
subject: fix name