class_docstr: OSS Filesystem Tests
code: def test_copy_overwrite(self):
      file_path = file_io.join(self._base_dir, "temp_file")
      with gfile.Open(file_path, mode="w") as f:
          f.write("testing")
      copy_path = file_io.join(self._base_dir, "copy_file")
      gfile.Open(copy_path, mode="w").write("copy")
      gfile.Copy(file_path, copy_path, overwrite=True)
      self.assertTrue(gfile.Exists(copy_path))
      self.assertEqual(
          "testing", gfile.Open(copy_path, mode="r").read()
      )
  
imports: import os
  import unittest
  from tensorflow.python.framework import errors
  from tensorflow.python.lib.io import file_io
  from tensorflow.python.platform import test
  from tensorflow.python.platform import gfile
  import tensorflow
  import tensorflow_io
label_desc: Use image node_id 18 for calling the OSSFSTest obj's underlying member method code with example usage: obj.test_copy_overwrite() without return types