'Store valid keys in _config.'

@patch('homeassistant.components.sensor.tcp.TcpSensor.update')
def test_config_valid_keys(self, *args):

    sensor = tcp.TcpSensor(self.hass, TEST_CONFIG['sensor'])
    del TEST_CONFIG['sensor']['platform']
    for key in TEST_CONFIG['sensor']:
        assert (key in sensor._config)
