def test_printFingerprintBadFingerPrintFormat(self):
        """
        L{printFigerprint} raises C{keys.BadFingerprintFormat} when unsupported
        formats are requested.
        """
        filename = self.mktemp()
        FilePath(filename).setContent(publicRSA_openssh)
        with self.assertRaises(BadFingerPrintFormat) as em:
            printFingerprint({'filename': filename, 'format':'sha-base64'})
        self.assertEqual('Unsupported fingerprint format: sha-base64',
            em.exception.args[0])

        L{printFigerprint} raises C{keys.BadFingerprintFormat} when unsupported
        formats are requested.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_ckeygen.py