Not able to mock S3 download request using proxyquire

Question

const awsSdk = require('aws-sdk');

module.exports = {

    downloadFile(bucketName, fileName, callback) {
        var s3 = new awsSdk.S3();
        var params = { Bucket: bucketName, Key: fileName };
        var file = require('fs').createWriteStream('abcd.jpg');
        var stream = s3.getObject(params).on('error', function (err) {
            console.log(' download.on');
            callback('error', null);
        })
        .createReadStream()
        stream.pipe(file);
    }
}

Above, is the code i need to mock in my Test class using proxyquire. The issue is, im not able to mock methods like getObject,on,createReadStream. Also after mocking i need to emit the error event from test class that will trigger the above on method which will call the callback in my test class where exception is tested.

Below is my test class code.

const proxyquire = require('proxyquire').noCallThru().noPreserveCache();
const sinon = require('sinon');
const emitter = require('events').EventEmitter;


function Download() {
    emitter.call(this);
    this.error = function () {
        this.emit('error');
    }
}

describe('S3 download test', () => {
    awsSdkMock = {}
    awsSdkMock.config = {};
    awsSdkMock.config.region = { };
    var s3Instance = {};    
    awsSdkMock.S3 = function (){
        return s3Instance;
    };
    var object = {};
    s3Instance.getObject = function (params){ 
        return object; 
    };

    var request = {};
    const errorCallBack = sinon.spy();
    var err = 'error';
    object.on = function (err, errorCallBack) {
        console.log('object.on');  
        errorCallBack();      
        return request;
    };
    var stream = {};
    request.createReadStream = function(){
        console.log('createReadStream');        
        return stream
    };
    stream.pipe = function(file){
        console.log('download.error');
       // download.error();            
    };



    Download.prototype.__proto__ = emitter.prototype;
    var download = new Download();



    const s3 = proxyquire('./../../../modules/s3', {
        'aws-sdk': awsSdkMock
    })


    it('Error in download test', (done) => {
        const errorCallBack = sinon.spy();
        s3.downloadFile('123', 'abcd', errorCallBack);
        sinon.assert.calledWith(errorCallBack, 'error', null);
        done();
    });
})

Any help is appreciated.