class_docstr: Image dataset for test split of `Cityscapes dataset`_.
  
  .. _`Cityscapes dataset`: https://www.cityscapes-dataset.com
  
  .. note::
  
      Please manually download the data because it is not allowed to
      re-distribute Cityscapes dataset.
  
  Args:
      data_dir (string): Path to the dataset directory. The directory should
          contain the :obj:`leftImg8bit` directory. If :obj:`auto` is given,
          it uses :obj:`$CHAINER_DATSET_ROOT/pfnet/chainercv/cityscapes` by
          default.
  
  This dataset returns the following data.
  
  .. csv-table::
      :header: name, shape, dtype, format
  
      :obj:`img`, ":math:`(3, H, W)`", :obj:`float32`,         "RGB, :math:`[0, 255]`"
code: def _get_image(self, i):
      return read_image(self.img_paths[i])
  
file_path: chainercv/chainercv/datasets/cityscapes/cityscapes_test_image_dataset.py
imports: import glob
  import os
  from chainer.dataset import download
  from chainercv.chainer_experimental.datasets.sliceable import GetterDataset
  from chainercv.utils import read_image
label_desc: Use image node_id 3 for calling the CityscapesTestImageDataset obj's underlying member method code with example usage: obj._get_image(i) and returns: read_image