'Shouldn\'t store invalid keys in _config.'

@patch('homeassistant.components.sensor.tcp.TcpSensor.update')
def test_config_invalid_keys(self, mock_update):

    config = copy(TEST_CONFIG['sensor'])
    config.update({'a': 'test_a', 'b': 'test_b', 'c': 'test_c'})
    sensor = tcp.TcpSensor(self.hass, config)
    for invalid_key in 'abc':
        assert (invalid_key not in sensor._config)
