Using chai-as-promised library and proxyrequire to test async functions

async-error-handling-chai.js

const chai = require('chai');
var chaiAsPromised = require('chai-as-promised');
chai.use(chaiAsPromised);
chai.should();

const mockStoryModel = {};
const proxyquire = require('proxyquire');

//creates mock model functions to replace original model functions in controller
const StoriesController = proxyquire('../controller/controller',
  { '../model/model' : mockStoryModel}
);

describe('Story', () => {

  const ctx = {request: {body:'foo'}};

  it ('createStory should catch errors from model', async () => {
    const foo = ctx.request.body;
    mockStory.createStory = (foo) => {
      throw new Error('error');
    };
    Story.createStory().should.be.rejected;
  });

});