'Check the return that _state is value_on.'

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

    sensor = bin_tcp.TcpBinarySensor(self.hass, test_tcp.TEST_CONFIG['sensor'])
    sensor._state = test_tcp.TEST_CONFIG['sensor'][tcp.CONF_VALUE_ON]
    print sensor._state
    assert sensor.is_on
