Unhandled rejection warnings when expecting a rejection

[laggingreflex]

I'm not using Bluebird but similarly to this thread I'm getting the same warning errors of unhanded rejection when actually expecting a rejection.

Here's a repo to reproduce: https://github.com/laggingreflex/chai-as-promised-reject-test

It was mentioned chai-as-promised is indeed handling the errors (here) but I think they're not being handled soon enough. Putting a console.log there shows that it reaches that code only after the warning has been displayed:

(node:5580) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: rejected
  promise
(node:5580) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 1)
>>> assertIfNegated about to be called... <<<
    √ should be rejected


  1 passing (48ms)

[domenic]

This is a bug introduced in Node.js v7.0.0. I can only recommend not using v7 for now. See nodejs/node#8217.

[darkobits]

I am also experiencing this issue on Node 6.9.1 and:

chai@3.5.0
chai-as-promised@6.0.0
mocha@3.1.0

This spec should fail:

import chai from 'chai';
import chaiAsPromised from 'chai-as-promised';

chai.use(chaiAsPromised);
const expect = chai.expect;

describe('Test', () => {
  it('should fail', () => {
    expect(Promise.resolve(2)).to.eventually.equal(1);
  });
});

Instead, the output is:

  Test
    ✓ should fail
(node:52529) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): AssertionError: expected 2 to equal 1

  4 passing (27ms)

And the process exits with a 0 exit code.

[domenic]

Ugh, it does seem this kind of major change slipped in to Node.js 6.x as well, although that bug thread is confusing :(.

[laggingreflex]

@darkobits I think you need to return the expect

  it('should fail', () => {
    return expect(Promise.resolve(2)).to.eventually.equal(1);
  });

Also I think my (OP) problem was that I was using chai v4, I tested it again and the original test lib works well with chai 3.5

[keithamus]

@laggingreflex do you think this might be a regression in chai v4? If so please please do file a report on the chai issue tracker 😄

[meeber]

Also might wanna check out #157. However, I submitted that a long time ago and there have been a lot of changes since then; it may need further updating.

[adamvoss]

Is this still considered a node bug? I am seeing this too in node 8.0.0.

const chai = require('chai');
chai.use(require("chai-as-promised"));
const assert = chai.assert;

describe('rejection assertion', function(){
  it('should correctly fail the test', function(){
    const p = Promise.resolve("resolved")
    return assert.isRejected(p)
  })
})

The above erroneously passes:

rejection assertion
✓ should correctly fail the test
(node:27794) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): AssertionError: expected promise to be rejected but it was fulfilled with 'resolved'
(node:27794) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

1 passing (37ms)

    "chai": "^4.0.1",
    "chai-as-promised": "^6.0.0",
    "mocha": "^3.4.2"

[meeber]

@adamvoss chai-as-promised doesn't support Chai v4 yet. See #198 and #157.

[zazoomauro]

I'm having exactly the same issue right there

version:
node: v6.11.0
chai: ^3.5.0
chai-as-promised: ^6.0.0
mocha: ^3.2.0
sinon: ^2.1.0

Source Code:

export default class SomeManager {
  /**
   * @param {SomeOtherManager} someOtherManager
   */
  constructor(someOtherManager) {
    this._someOtherManager = someOtherManager;
  }

  /**
   * @return {Promise}
   */
  execute() {
    return this._someOtherManager.get('id');
  }
}

Spec file:

import chai from 'chai';
import cp from 'chai-as-promised';
import SomeManager from './../../lib/manager/someManager';
import SomeOtherManager from './../../lib/manager/someOtherManager';
import {beforeEach, describe, it} from 'mocha';
import sinon from 'sinon';

describe('SomeManager', () => {
  chai.use(cp);
  let expect = chai.expect;
  let someManager;
  let someOtherManagerMock;

  beforeEach(() => {
    someOtherManagerMock = sinon.createStubInstance(SomeOtherManager);
    someManager = new SomeManager(someOtherManagerMock);
  });

  describe('execute', () => {
    it('should reject promise', () => {
      // Arrange.
      someOtherManagerMock.get.withArgs('id').returns(Promise.reject());

      // Act.
      let actual = someManager.execute();

      // Assert.
      return expect(actual).to.eventually.be.resolved;
    });
  });
});

Output:

SomeManager
    execute
      ✓ should reject promise
(node:11844) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): undefined

With node: 8.1.0 different Output:

    execute
      ✓ should reject promise
(node:12102) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): undefined
(node:12102) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

[meeber]

@zazoomauro In your case, the problem is that .resolved isn't an assertion in chai-as-promised. I think you need .fulfilled.

[zazoomauro]

@meeber Thanks!

[ChrisCurrin]

I also have the same problem
node: v6.11.0
chai: 3.5.0 -- also tested on ^4.0.1
chai-as-promised: ^7.1.1
mocha: ^3.4.2

[vitalets]

Have the same issue.
The solution for node:

process.on('unhandledRejection', () => {});