code: def testDeleteDir(self):
      self.createFiles({"dir": {"file.txt": "testing"}})
      io_utils.delete_dir(self.relpath("dir"))
      self.assertDirectoryEqual(self._base_dir, {})
  
imports: import os
  from unittest import mock
  import tensorflow
  from tfx.dsl.io import fileio
  from tfx.utils import io_utils
  from tensorflow.python.lib.io import file_io
label_desc: Use image node_id 16 for calling the IoUtilsTest obj's underlying member method code with example usage: obj.testDeleteDir() without return types