Expected rejections should not raise 'unhandledRejection'

[erikerikson]

Apologies if this is not the exact right place to raise this...

Reproduction available at https://github.com/erikerikson/chai-bluebird

Using:

OS X, version 10.12.6 (16G1114)

$node --version
v6.11.0

{
    "bluebird": "^3.5.1",
    "chai": "^4.1.2",
    "chai-as-promised": "^7.1.1",
    "mocha": "^5.0.0"
}

Executing:

const BbPromise = require('bluebird');
const chai = require('chai');

chai.use(require('chai-as-promised'))

const expect = chai.expect;

process.on('unhandledRejection', err => {
    console.log(`UNHANDLED! ${err}`);
    throw err;
});

describe('Variables', function variables() {
    it('simpler', () => {
        return expect(BbPromise.reduce([
            BbPromise.resolve('foo'),
            BbPromise.resolve('bar'),
            BbPromise.reject('reason')
        ])).to.be.rejected;
    })
});

Outputs:

chai-bluebird $npm test

> chai-bluebird@1.0.0 test ~/chai-bluebird
> mocha test.spec.js



  Variables
    1) simpler
UNHANDLED! reason
UNHANDLED! TypeError: expecting a function but got [object Undefined]

~/chai-bluebird/node_modules/mocha/lib/runner.js:707
  err.uncaught = true;
               ^

TypeError: Cannot create property 'uncaught' on string 'reason'
    at Runner.uncaught (~/chai-bluebird/node_modules/mocha/lib/runner.js:707:16)
    at process.uncaught (~/chai-bluebird/node_modules/mocha/lib/runner.js:821:10)
    at emitOne (events.js:96:13)
    at process.emit (events.js:188:7)
    at process._fatalException (bootstrap_node.js:296:26)
npm ERR! Test failed.  See above for more details.

[erikerikson]

FWIW, this also behaves similarly if one rejects with an Error instead of with a string:
https://github.com/erikerikson/chai-bluebird/blob/reject-error/test.spec.js#L18

Normally you will observe:

~/chai-bluebird $npm test

> chai-bluebird@1.0.0 test ~/chai-bluebird
> mocha test.spec.js



  Variables
UNHANDLED! Error: reason
    ✓ simpler


  1 passing (12ms)

Note the "UNHANDLED" message indicating that the process emitted an 'unhandledRejection' event.

You may have to run npm test a number of times but if you (with this same code) eventually you will see:

~/chai-bluebird $npm test

> chai-bluebird@1.0.0 test ~/chai-bluebird
> mocha test.spec.js



  Variables
UNHANDLED! Error: reason
    1) simpler
    ✓ simpler


  1 passing (11ms)
  1 failing

  1) Variables
       simpler:
     Uncaught Error: reason
      at Context.it (test.spec.js:19:24)




  1 passing (12ms)
  1 failing

  1) Variables
       simpler:
     Uncaught Error: reason
      at Context.it (test.spec.js:19:24)



npm ERR! Test failed.  See above for more details.

Note the double report and "phantom" test.

[meeber]

@erikerikson I believe this issue is related to petkaantonov/bluebird#1487. I'd recommend letting them know you're running into the same issue with .reduce. (I tested your example with bluebird@3.5.0 and the problem went away).

[erikerikson]

Thank you @meeber I've narrowed this down further and it does not relate to chai. Have reported to bluebird. Apologies for the noise.