How to compare the response of multiple GET requests after they all complete

Question

I want to make sure the each time I make a specific get request I get the same result for a specific array in the body called spells. (SIDE NOTE: I will also write a different test to make sure another part of the body active_spell is random/different at least some of the time). I've written the following code but can't seem to get into the 'data' or 'end' events.

So why am I not getting into the 'data' and 'end' events?

And really the main question, is there a more proper or efficient way to reach my main objective, which is to ensure the spellbooks returns the same each time?

NOTE: I Don't mind looking at libraries to help with this, but I am looking for a way to do this without needing to add more.

var config = require('./../config');

//Setup client with automatic tests on each response 
var api = require('nodeunit-httpclient').create({
    host: config.api.host,
    port: config.api.port,
    path: '/api', //Base URL for requests
    status: 200, //Test each response is OK (can override later)
    headers: { //Test that each response must have these headers (can override later)
        'content-type': 'application/json'
    }
});

exports.spellbook_get = {
 'ensure spells are always the same': function(test) {
    //2 default tests in the client plus the one below
    test.expect(3);

    var urls = ['/spellbook', '/spellbook', '/spellbook', '/spellbook'];
    var completed_requests = 0;

    urls.forEach(function(url) {
        var responses = [];

        api.get(test, url, function(res) {

            res.on('data', function(chunk){
                console.log('YAY!-DATA');
                responses.push(chunk);
            });

            res.on('end', function(){
                console.log('YAY!-END');
                if (completed_requests++ == urls.length - 1) {
                    // All requests are completed
                    var uniques = [],
                        hashes = {};

                    for (var i=0; i < responses.length; i++) {
                        var hash = JSON.stringify(responses[i].spells);
                        if (!(hash in hashes)) {
                            hashes[hash] = true;
                            uniques.push(responses[i].spells);
                        }
                    }
                    //test that there is only 1 unique array
                    test.equal(uniques.length, 1, 'All spells responses must match');
                    test.done();
                }
            });
        });
    });
  }
};