code: def test_falls_back_to_stdin(self):
      with mock.patch("os.open") as os_open, mock.patch(
          "sys.stdin", spec=StringIO
      ) as stdin:
          os_open.side_effect = IOError
          stdin.fileno.side_effect = AttributeError
          with support.captured_stderr() as stderr:
              with self.assertWarns(getpass.GetPassWarning):
                  getpass.unix_getpass()
          stdin.readline.assert_called_once_with()
          self.assertIn("Warning", stderr.getvalue())
          self.assertIn("Password:", stderr.getvalue())
  
imports: import getpass
  import os
  import unittest
  from io import BytesIO, StringIO, TextIOWrapper
  from unittest import mock
  from test import support
label_desc: Use image node_id 5 for calling the UnixGetpassTest obj's underlying member method code with example usage: obj.test_falls_back_to_stdin() without return types