Why doesn't this test with promises pass?

I've stepped into wonderful world of Promises a few days ago and I was just thinking I was enlightened. Promises look simple but they can be confusing.

Could you please tell me why the following test doesn't pass?

var Promise = require('bluebird');
var expect = require('chai').expect;
var request = Promise.promisifyAll(require('request'));

describe('Promise', function() {
    it('should work again', function() {

        var final_result;

        function first_promise() {
            return new Promise(function(resolve, reject) {
                resolve("http://www.google.com");
            })
        }

        function second_promise() {
            return new Promise(function(resolve, reject) {
                resolve("This is second promise!");
            })
        }

        function inner_async_request(url_from_first_promise) {
            return new Promise(function(resolve, reject) {
                return request.getAsync(url_from_first_promise).spread(function(response, content) {
                    final_result = content;
                    resolve(content);
                })
            })
        }

        return request.getAsync('http://127.0.0.1:3000/').spread(function(result, content) {
                //do something with content and then return first_promise
                console.log(content);
                return first_promise;
            })
            .then(function(url) {
                inner_async_request(url).then(function(result) {
                    console.log(result);
                    final_result = result;
                })
                return second_promise;
            })
            .then(function(result) {
                // result should be "This is second promise!"
                console.log(result);
                // final_result should be google's html
                expect(final_result).not.to.be.undefined;
            })
    });
});

Currently the error is: Unhandled rejection Error: options.uri is a required argument which should be received from first_promise, I guess?

By this test, actually, I want to understand how to use promises which depend on each other AND how to use promises as asynchronous functions inside promises -which should just work separately-.

Thank you