code: def setUp(self):
      if self.file_obj:
          self.f = tempfile.TemporaryFile()
          self.file = self.f
          format = self.format
      else:
          if self.format == "jpeg":
              suffix = ".jpg"
          else:
              suffix = "." + self.format
          self.f = tempfile.NamedTemporaryFile(
              suffix=suffix, delete=False
          )
          self.file = self.f.name
          format = None
  
      self.img = np.random.randint(
          0, 255, size=self.size, dtype=np.uint8
      )
      write_image(self.img[None], self.file, format=format)
      if self.file_obj:
          self.file.seek(0)
  
file_path: chainercv/tests/utils_tests/image_tests/test_read_label.py
imports: import numpy
  import tempfile
  import unittest
  from chainer import testing
  from chainercv.utils import read_label
  from chainercv.utils import write_image
label_desc: Use image node_id 1 for calling the TestReadLabel obj's underlying member method code with example usage: obj.setUp() without return types