'L{_saveKey} will choose an empty string for the passphrase if
no-passphrase is C{True}.'

def test_saveKeyEmptyPassphrase(self):

    base = FilePath(self.mktemp())
    base.makedirs()
    filename = base.child('id_rsa').path
    key = Key.fromString(privateRSA_openssh)
    _saveKey(key, {'filename': filename, 'no-passphrase': True, 'format': 'md5-hex'})
    self.assertEqual(key.fromString(base.child('id_rsa').getContent(), None, ''), key)
