class_docstr: OSS Filesystem Tests
code: def test_file_doesnt_exist(self):
      file_path = file_io.join(self._base_dir, "temp_file")
      self.assertFalse(gfile.Exists(file_path))
      with self.assertRaises(errors.NotFoundError):
          _ = file_io.read_file_to_string(file_path)
  
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 7 for calling the OSSFSTest obj's underlying member method code with example usage: obj.test_file_doesnt_exist() without return types