awsProvider.js

'use strict';

const AWS = require('aws-sdk');
const BbPromise = require('bluebird');

class AwsProvider {
  request(service, method, params) {
    const awsService = new AWS[service]();
    const req = awsService[method](params);

    return new BbPromise((resolve, reject) => {
      req.send((errParam, data) => {
        const err = errParam;
        if (err) {
          reject(new Error(err.message, err.statusCode));
        } else {
          resolve(data);
        }
      });
    });
  }
}

module.exports = new AwsProvider();

index.js

'use strict';
const aws = require('./awsProvider');
const BbPromise = require('bluebird');

class Index {
  constructor() {
    this.provider = aws;
  }

  method() {
    return this.provider.request('STS',
      'getCallerIdentity',
      {}
    ).then((result) => {
      return BbPromise.resolve(result);
    });
  }
}

module.exports = Index;

index.test.js

'use strict';

const expect = require('chai').expect;
const BbPromise = require('bluebird');
const sinon = require('sinon');
const Index = require('./index');

describe('index', () => {
  let index;

  beforeEach(() => {
    index = new Index();
  });

  describe('method', () => {
    let stsStub;
    beforeEach(() => {
      stsStub = sinon.stub(index.provider, 'request')
          .returns(BbPromise.resolve({}));
    });
    it('should the correct value', () => {
      index.aa().then(() => {
        expect(stsStub.calledOnce).to.be.equal(true);
        expect(stsStub.calledWithExactly(
          'STS',
          'getCallerIdentity',
          {}
        )).to.be.equal(true);
        index.provider.request.restore();
      });
    });
  });
});