testing-rejections-with-chai2.js

import thirdPartyClient from 'some-third-party-client'
import myApi            from '../../src/my-api'

describe('myApi', () => {
  describe('Error handling', () => {
    const myRejection = {
      errorCode: 404,
      errorMessage: 'You broke everything',
      errorUrl: 'http://coolapp.api.docs/error/404/'
    }
    
    beforeEach(() => {
      sinon.stub(thirdPartyClient.prototype, 'dingus')
         .returns(Promise.reject(myRejection)
    })

    afterEach(() => thirdPartyClient.prototype.dingus.restore())
    
    it('should be rejected with the correct error object', () => {
      const expected = myRejection
      
      return myApi.someMethod()
        .then(() => {
          const actual = thirdPartyClient.prototype.dingus
          return expect(actual).to.be.rejected
            .and.to.eventually.deep.equal(expected)
        })
    })
  })
})