awsLib.js

import AWS from 'aws-sdk';
import config from './config.js';
import sigV4Client from './sigV4Client';

export function getAwsCredentials(userToken) {
  const authenticator = `cognito-idp.${config.cognito.REGION}.amazonaws.com/${config.cognito.USER_POOL_ID}`;

  AWS.config.update({ region: config.cognito.REGION });

  AWS.config.credentials = new AWS.CognitoIdentityCredentials({
    IdentityPoolId: config.cognito.IDENTITY_POOL_ID,
    Logins: {
      [authenticator]: userToken
    }
  });

  return AWS.config.credentials.getPromise();
}

test-snippet.js

const chakram = require('chakram'),
    expect = chakram.expect;

const util = require('util');

const aws = require('aws-sdk');
const amazonCognitoIdentity = require('amazon-cognito-identity-js');

const config = require('../secrets.json');
const myconfig = require('./config.js');

const awsLib = require('./awsLib.js'); // provided in gist
import sigV4Client from './sigV4Client.js'; // identical to the sigV4Client from the tutorial

const cognitoUserPool = amazonCognitoIdentity.CognitoUserPool;

// Set the AWS region
aws.config.update({ region: config.AwsRegion });

// The API portion being tested
const card_route = "/cards" // my modification - I'm creating "cards" instead of "notes"

const cisp = new aws.CognitoIdentityServiceProvider({ apiVersion: '2016-04-18' });

const params = {
    AuthFlow: 'ADMIN_NO_SRP_AUTH',
    ClientId: config.AwsAppClientId,
    UserPoolId: config.CognitoUserPoolId,
    AuthParameters: {
        USERNAME: config.CognitoTestUsername,
        PASSWORD: config.CognitoTestPassword
    }
};

var adminInitiateAuthPromise = cisp.adminInitiateAuth(params).promise();

const getSignedRequest = function (method, path, headers, queryParams, body) {
    const signedRequest = sigV4Client
        .newClient({
            accessKey: aws.config.credentials.accessKeyId,
            secretKey: aws.config.credentials.secretAccessKey,
            sessionToken: aws.config.credentials.sessionToken,
            region: myconfig.default.apiGateway.REGION,
            endpoint: myconfig.default.apiGateway.URL,
        })
        .signRequest({
            method,
            path,
            headers,
            queryParams,
            body
        });

    return signedRequest;
}

describe("cards API", function () {
    var opts = {};

    before("test setup", function () {
        return adminInitiateAuthPromise
            .then(function (auth) {
                const idToken = auth.AuthenticationResult.IdToken;


                return awsLib.getAwsCredentials(idToken);
            });
    });

    it("should support a put (create) and delete endpoints", function () {
        const body = JSON.stringify({
            'url': 'my_new_url',
            'title': 'My new title',
            'description': 'My new description'
        });

        const method = 'POST';

        const signedRequest = getSignedRequest(method, card_route, {}, {}, body);

        const opts = {
            'headers': signedRequest.headers,
            'body': signedRequest.body
        };

        console.log(signedRequest);
        return chakram.request(signedRequest.method, signedRequest.url, opts).then(function (postResponse) {
          
          // ... the test should continue here. but this request returns the 403 error I described.