Sinon.Stub in Node with AWS-SDK

Question

I am trying to write some test coverage for an app that uses the aws-sdk NPM module that pushes things up to a SQS queue, but I am unsure how to mock things correctly.

Here is my test so far:

var request = require('superagent'),
    expect = require('chai').expect,
    assert = require('chai').assert,
    sinon = require('sinon'),
    AWS = require('aws-sdk'),
    app = require("../../../../app");

describe("Activities", function () {

    describe("POST /activities", function () {

        beforeEach(function(done) {
            sinon.stub(AWS.SQS.prototype, 'sendMessage');

            done();
        });

        afterEach(function(done) {
            AWS.SQS.prototype.sendMessage.restore();

            done();
        });

        it("should call SQS successfully", function (done) {
            var body = {
                "custom_activity_node_id" : "1562",
                "campaign_id" : "318"
            };

            reqest
            .post('/v1/user/123/custom_activity')
            .send(body)
            .set('Content-Type', 'application/json')
            .end(function(err, res) {
                expect(res.status).to.equal(200)

                assert(AWS.SQS.sendMessage.calledOnce);
                assert(AWS.SQS.sendMessage.calledWith(body));
            });
        });

    });

});

The error I am seeing is:

  1) Activities POST /activities "before each" hook:
     TypeError: Attempted to wrap undefined property sendMessage as function

  2) Activities POST /activities "after each" hook:
     TypeError: Cannot call method 'restore' of undefined

I am a bit of a newb when it comes to sinon.stub or mocking objects in JavaScript, so please excuse my ignorance

Answer 1

This is how I stub the AWS-SDK using sinonjs

import AWS from 'aws-sdk'
import sinon from 'sinon'

let sinonSandbox

const beforeEach = (done) => {
   sinonSandbox = sinon.sandbox.create()
   done()
}

const afterEach = done => {
   sinonSandbox.restore()
   done()
} 
lab.test('test name', (done) => {
    sinonSandbox.stub(AWS, 'SQS')
      .returns({
        getQueueUrl: () => {
          return {
            QueueUrl: 'https://www.sample.com'
          }
        }
    })
    done()
})

Basically I control all the methods from the main SQS. Hope this will help someone

Answer 2

We have created an aws-sdk-mock npm module which mocks out all the AWS SDK services and methods. https://github.com/dwyl/aws-sdk-mock

It's really easy to use. Just call AWS.mock with the service, method and a stub function.

AWS.mock('SQS', 'sendMessage', function(params, callback) {
    callback(null, 'success');
});

Then restore the methods after your tests by calling:

AWS.restore('SQS', 'sendMessage');

Answer 3

I think the issue is that AWS SDK classes are built dynamically from JSON configuration. Here's the one for SQS: Github.

All API calls eventually make it down to makeRequest or makeUnauthenticatedRequest on Service, so I just stubbed those using withArgs(...). For example:

var stub = sinon.stub(AWS.Service.prototype, 'makeRequest');
stub.withArgs('assumeRole', sinon.match.any, sinon.match.any)
    .yields(null, fakeCredentials);

which worked fine for my simple use case.