Unit test of authenticateUser - aws-cognito-identity-js - sinon/proxyquire

Question

I am new to node js and testing in general. I manage to use sinon to stub my functions etc but now I have to test a function that sends callback depending on event (onSuccess, onFailure).

Here is the code I need to test.

var AWSCognito = require('amazon-cognito-identity-js');

exports.getToken = function (options, callback) {
  var poolData = {
    UserPoolId : options.UserPoolId,
    ClientId : options.ClientId,
  };
  var authenticationData = {
    Username : options.username,
    Password : options.password,
  };
  var userPool = new AWSCognito.CognitoUserPool(poolData);
  var authenticationDetails = new AWSCognito.AuthenticationDetails(authenticationData);
  var userData = {
    Username : options.username,
    Pool : userPool
  };

  var cognitoUser = new AWSCognito.CognitoUser(userData);

  cognitoUser.authenticateUser(authenticationDetails, {
    onSuccess: function (result) {
      callback(null, {idToken: result.getIdToken().getJwtToken()});
    },
    onFailure: function (err) {
      callback(err);
    },
  });
}

this is what I did so far.

var proxyquire = require('proxyquire'); var should = require('should'); var sinon = require('sinon'); var AWSCognito = require('amazon-cognito-identity-js');

describe('authentication tests', function () {   var expectedResult;

  it('should invoke a lambda function correctly', function (done) {
    var options = {
      username: 'username1',
      password: 'pwd',
      UserPoolId : 'user_Pool',
      ClientId : 'clientId'
    };
    var expectedResult = {
      idToken: '123u'
    };

    var authenticateUserStub = sinon.stub().yieldsTo('onSuccess');

    var testedModule = proxyquire('../../../api/helpers/authentication.js', {
      'amazon-cognito-identity-js': {
        'CognitoUser': function () {
          return {
            authenticateUser: authenticateUserStub
          }
        }
      }
    });

    testedModule.getToken(options, function (err, data) {
      // should.not.exist(err);
      // data.should.eql(expectedResult);
      done();
    });   }); });

This is what I get as error

TypeError: Cannot read property 'getIdToken' of undefined
    at onSuccess (api/helpers/authentication.js:25:38)
    at callCallback (node_modules/sinon/lib/sinon/behavior.js:95:18)
    at Object.invoke (node_modules/sinon/lib/sinon/behavior.js:128:9)
    at Object.functionStub (node_modules/sinon/lib/sinon/stub.js:98:47)
    at Function.invoke (node_modules/sinon/lib/sinon/spy.js:193:47)
    at Object.proxy [as authenticateUser] (node_modules/sinon/lib/sinon/spy.js:89:22)
    at Object.exports.getToken (api/helpers/authentication.js:23:15)
    at Context.<anonymous> (test/api/helpers/authenticationTests.js:37:18)

It looks like it is going into the onSuccess function and then it does not recognize getIdToken. But it is going too far into the test, no? I only want to stub/mock authenticateUser and return a dummy response.

How can I just tell sinon to give me back a callback on 'onSuccess' without going into the details of the callback?

Thanks for your help

tswaters · Answer 1 · 2017-12-17T23:07:47.177

You need to pass additional parameters to the callback via yieldsTo. e.g.,

const getJwtTokenStub = sinon.stub()
const authenticateUserStub = sinon.stub().yieldsTo('onSuccess', {
  getIdToken: sinon.stub().returns({getJwtToken: getJwtTokenStub})
});

// then later, 
assert.equal(getJwtTokenStub.callCount, 1)

That said, it may not be valuable to have this stuff unit tested. You're basically stubbing out a slew of third party functionality and to do what - verify a function gets called?

Having test coverage for this might be better as an integration test - where you take out the stubs and actually hit aws with credentials specifically used for testing to make sure your app is calling everything correctly.

Thank you, I will try your solution. Yes, it is to test if our getToken function is doing what it is supposed to do. But like you said an integration test is more appropriate to test the aws-sdk with credentials etc. I agree with you — nguyeti, Dec 17 '17 at 21:17

Unit test of authenticateUser - aws-cognito-identity-js - sinon/proxyquire

1 Answers1