def test_fromPrivateBlobUnsupportedType(self):
        """
        C{BadKeyError} is raised when loading a private blob with an
        unsupported type.
        """
        badBlob = common.NS(b'ssh-bad')

        self.assertRaises(
            keys.BadKeyError, keys.Key._fromString_PRIVATE_BLOB, badBlob)

        C{BadKeyError} is raised when loading a private blob with an
        unsupported type.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_keys.py