'L{SSHProtocolChecker.requestAvatarId} should defer to one if its
registered checkers to authenticate a user.'

def test_requestAvatarId(self):

    checker = checkers.SSHProtocolChecker()
    passwordDatabase = InMemoryUsernamePasswordDatabaseDontUse()
    passwordDatabase.addUser('test', 'test')
    checker.registerChecker(passwordDatabase)
    d = checker.requestAvatarId(UsernamePassword('test', 'test'))
    def _callback(avatarId):
        self.assertEqual(avatarId, 'test')
    return d.addCallback(_callback)
