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Using spread with mocha doesn't work as expected #9296

zazoomauro opened this Issue Jan 8, 2019 · 1 comment


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zazoomauro commented Jan 8, 2019

Bug Report

Current Behavior
When I'm running mocha on some code using spread ... there is an error coming out:
ReferenceError: arrayWithoutHoles is not defined

Input Code

  • REPL or Repo link if applicable:

Source Code

export default class SomeClass {
  async someMethod(array) {
    const newArray = []
    return newArray


import chai from 'chai';
import cp from 'chai-as-promised';
import {beforeEach, describe, it} from 'mocha';
import SomeClass from './someClass';

describe('SomeClass', () => {
  const expect = chai.expect;
  let someClass;

  beforeEach(() => {
    someClass = new SomeClass();

  describe('someMethod', () => {
    it('should retrieve an array', () => {
      // Arrange.
      const array = [1,2,3]

      // Act.
      const actual = someClass.someMethod(array)

      // Assert.
      return expect(actual).to.eventually.equals(array);
"test": "cross-env NODE_ENV=test mocha"

Expected behavior/code
In theory, the test should be green or red but is throwing an exception
ReferenceError: arrayWithoutHoles is not defined at _toConsumableArray (someClass.js:8:36)

Babel Configuration (.babelrc, package.json, cli command)

  "presets": [
        "exclude": [
  "plugins": [


"devDependencies": {
    "@babel/cli": "^7.2.3",
    "@babel/core": "^7.2.2",
    "@babel/plugin-proposal-object-rest-spread": "^7.2.0",
    "@babel/preset-env": "^7.2.3",
    "@babel/register": "^7.0.0",


  • Babel version(s): 7
  • Node/npm version: 11
  • OS: OSX Mojave
  • Monorepo: npm
  • How you are using Babel: cli

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babel-bot commented Jan 8, 2019

Hey @zazoomauro! We really appreciate you taking the time to report an issue. The collaborators
on this project attempt to help as many people as possible, but we're a limited number of volunteers,
so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack
that typically always has someone willing to help. You can sign-up here
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