code: def setUp(self):
      self.temp_dir = tempfile.mkdtemp()
      img_dir = os.path.join(
          self.temp_dir, "leftImg8bit/{}/aachen".format(self.split)
      )
      resol = "gtFine" if self.label_mode == "fine" else "gtCoarse"
      label_dir = os.path.join(
          self.temp_dir, "{}/{}/aachen".format(resol, self.split)
      )
      os.makedirs(img_dir)
      os.makedirs(label_dir)
  
      for i in range(10):
          img = np.random.randint(0, 255, size=(3, 128, 160)).astype(
              np.uint8
          )
          write_image(
              img,
              os.path.join(
                  img_dir,
                  "aachen_000000_0000{:02d}_leftImg8bit.png".format(i),
              ),
          )
  
          label = np.random.randint(0, 34, size=(1, 128, 160)).astype(
              np.int32
          )
          write_image(
              label,
              os.path.join(
                  label_dir,
                  "aachen_000000_0000{:02d}_{}_labelIds.png".format(
                      i, resol
                  ),
              ),
          )
  
      self.dataset = CityscapesSemanticSegmentationDataset(
          self.temp_dir, self.label_mode, self.split, self.ignore_labels
      )
  
imports: import numpy
  import os
  import shutil
  import tempfile
  import unittest
  from chainer import testing
  from chainer.testing import attr
  from chainercv.datasets.cityscapes.cityscapes_utils import cityscapes_labels
  from chainercv.datasets import CityscapesSemanticSegmentationDataset
  from chainercv.datasets import CityscapesTestImageDataset
  from chainercv.utils import assert_is_semantic_segmentation_dataset
  from chainercv.utils.testing.assertions.assert_is_image import assert_is_image
  from chainercv.utils import write_image
label_desc: Use image node_id 1 for calling the TestCityscapesSemanticSegmentationDataset obj's underlying member method code with example usage: obj.setUp() without return types