new_contents: import unittest
  
  import numpy as np
  
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
  
  from chainercv.datasets import voc_semantic_segmentation_label_names
  from chainercv.datasets import VOCSemanticSegmentationDataset
  
  
  @testing.parameterize(
      {'split': 'train'},
      {'split': 'val'},
      {'split': 'trainval'}
  )
  class TestVOCSemanticSegmentationDataset(unittest.TestCase):
  
      def setUp(self):
          self.dataset = VOCSemanticSegmentationDataset(split=self.split)
  
      @attr.slow
      @condition.repeat(10)
      def test_camvid_dataset(self):
          i = np.random.randint(0, len(self.dataset))
  
          img, label = self.dataset[i]
  
          self.assertIsInstance(img, np.ndarray)
          self.assertEqual(img.dtype, np.float32)
          self.assertEqual(img.shape[0], 3)
          self.assertGreaterEqual(np.min(img), 0)
          self.assertLessEqual(np.max(img), 255)
  
          self.assertIsInstance(label, np.ndarray)
          self.assertEqual(label.dtype, np.int32)
          self.assertEqual(label.shape, img.shape[1:])
          self.assertGreaterEqual(np.min(label), -1)
          self.assertLessEqual(
              np.max(label), len(voc_semantic_segmentation_label_names) - 1)
  
  
  testing.run_module(__name__, __file__)
  
subject: add tests for voc_semantic_segmentation_dataset