def test_changePassphraseWithOld(self):
        """
        L{changePassPhrase} allows a user to change the passphrase of a
        private key, providing the old passphrase and prompting for new one.
        """
        newConfirm = makeGetpass('newpass', 'newpass')
        self.patch(getpass, 'getpass', newConfirm)

        filename = self.mktemp()
        FilePath(filename).setContent(privateRSA_openssh_encrypted)

        changePassPhrase({'filename': filename, 'pass': 'encrypted'})
        self.assertEqual(
            self.stdout.getvalue().strip('\n'),
            'Your identification has been saved with the new passphrase.')
        self.assertNotEqual(privateRSA_openssh_encrypted,
                            FilePath(filename).getContent())

        L{changePassPhrase} allows a user to change the passphrase of a
        private key, providing the old passphrase and prompting for new one.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_ckeygen.py