text: // this file can be used to test if
  // the connection to the mqtt broker works
  let mqtt = require('mqtt')
  let config = require('./config.json')
  let client = mqtt.connect(
      config.mqtt_broker,
      config.mqtt_options
    );
    let messageContent = 'secret message';
    let channel = 'test/message/';
  console.log('Trying to connect to mqtt broker...');
  client.on('connect', function () {
    console.log(`successfully connected!
    publishing a message to ${channel} with content:
    ${messageContent}`);
    client.publish(channel, messageContent);
    client.end();
  })
   
  client.on('message', function (topic, message) {
    // message is Buffer
    console.log(`recieved message, with the following content:
    ${message.toString()}`);
    client.end()
  })