Mangled exception handling with `chai-as-promised` leads to mocha silently exiting without reporting an error

I don’t know if this is supported or not, but it causes a very vicious silent error which causes the rest of the unit tests to not run and mocha to immediately exit with 0, reporting a global success - which means that automated unit testing doesn’t report any error

It is somewhat random, depending on the Node version - I have a repo that can reproduce it with 100% probability on Node 14 on Ubuntu 20.04

Normally ds.root.arrays.getAsync('time') returns a Promise that resolves with a gdal.MDArray It is a promisified function of a function that calls a callback In this particular case getAsync() is throwing synchronously from C++ and then proceeding to invoke its callback which causes the exception to be propagated in a very unusual way going higher up the chain.

it('should have "getAsync()" method', (done) => {
  assert.eventually.instanceOf(ds.root.arrays.getAsync('time'), gdal.MDArray).then(done)
})

[mmomtchev]

@sukrosono I think I found the problem: https://github.com/nodejs/node/issues/29355

[mmomtchev]

@sukrosono I was able to reproduce the problem without any C++ shenanigans

npm i mocha chai chai-as-promised

mocha.test.js

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

function asyncIterator() {
  let i = 0
  const count = 10

  return {
    next: () => Promise.resolve(count)
      .then((count) => {
        if (i++ < count) {
          return Promise.resolve(i).then((value) => ({ done: false, value }))
        }
        return { done: true, value: null }
      })
  }
}

it('asyncIterator', (done) => {
  const w = []
  const it = asyncIterator()
  const recurse = (r) => {
    if (r.done) {
      assert(w.length == 0) // This will throw
      done()
    } else {
      w.push(r.value)
      it.next().then(recurse)
    }
  }
  it.next().then(recurse)
})

.mocharc.json

{
  "timeout": 0
}

If you run this test, mocha will silently exit with a 0 exit code, indicating success, upon hitting the exception. If the file contain other tests, they will be silently ignored.