Testing the request library

To test, we'll save the file, move into Terminal, and shut down nodemon for the promise.js file. We'll run node for the promise.js file. It's in the playground folder, and it's called promise-2.js:

node playground/promise-2.js

Now, when we run this program, we're actually making that HTTP request. As shown in the following code output, we can see the data comes back exactly as we expected:

We get our address, latitude, and longitude variables. This is fantastic! Now let's test to see what happens when we pass in an invalid address, something like 5 zeroes, which we've used before to simulate an error:

const request = require('request');

var geocodeAddress = (address) => {
  return new Promise((resolve, reject) => {
    var encodedAddress = encodeURIComponent(address);

  request({
   url: `https://maps.googleapis.com/maps/api/geocode/json?address=${encodedAddress}`,
   json: true
 }, (error, response, body) => {
   if (error) {
     reject('Unable to connect to Google servers.');
   } else if (body.status === 'ZERO_RESULTS') {
     reject('Unable to find that address.');
   } else if (body.status === 'OK') {
     resolve({
       address: body.results[0].formatted_address,
       latitude: body.results[0].geometry.location.lat,
       longitude: body.results[0].geometry.location.lng
      });
     }
   });
  });
};

We'll save the file, rerun the program, and Unable to find that address. prints to the screen:

This happens only because we call reject. We will call reject inside of the Promise constructor function. We have our error handler, which prints the message to the screen. This is an example of how to take a library that does not support promises and wrap it in a promise, creating a promise ready function. In our case, that function is geocodeAddress.