moment-timezone.js – Getting Error When Running in Jest Test

[friendken]

Hi moment-timezone team, Firstly, I want to thank you very much for great package.

I got an error using moment-timezone.js. It runs perfectly on a web page, but when I try to implement the test for it, the test result always returns an error like below.

import moment from 'moment-timezone';

class TimezoneCityItem extends React.Component {

  componentDidMount(){
    this.setState({
      time: moment.tz(this.props.timezone)
    })
  }

  render(){
    return (
      <div>{this.state.time.format('HH:mm')}</div>
    )
  }
}

This is timezoneListDummyData:

const timezoneList = [
  { name: 'los-angeles', title: 'Los Angeles', timezone: 'America/Los_Angeles' },
  { name: 'washington', title: 'Washington', timezone: 'America/New_York' },
  { name: 'london', title: 'London', timezone: 'Europe/London' },
  { name: 'dubai', title: 'Dubai', timezone: 'Asia/Dubai' },
  { name: 'hongkong', title: 'Hongkong', timezone: 'Asia/Hong_Kong' },
];

export default timezoneList;

this is code I use on my test file

import React from 'react';
import { shallow } from 'enzyme';
import TimezoneCityItem from '../TimezoneCity.item';
import timezoneList from '/lib/timezoneListDummyData'; // It just an array list of timezone

describe('<TimezoneCityItem />', () => {
   test('Should render TimezoneCityItem correctly', () => {
       const wrapper = shallow(<TimezoneCityItem {...timezoneList[0]} />);
       expect(wrapper).toMatchSnapshot();
   });
});

This is the version of the packages:

"moment": "~2.18.1",
"moment-timezone": "~0.5.13",

This is the error message:

Test suite failed to run
TypeError: Cannot read property 'split' of undefined

  at node_modules/moment-timezone/moment-timezone.js:36:34
  at Object.<anonymous>.moment (node_modules/moment-timezone/moment-timezone.js:14:20)
  at Object.<anonymous> (node_modules/moment-timezone/moment-timezone.js:18:2)
  at Object.<anonymous> (node_modules/moment-timezone/index.js:1:120)
  at Object.<anonymous> (imports/ui/components/mainLayout/TimezoneCity.item.jsx:3:49)
  at Object.<anonymous> (imports/ui/components/mainLayout/TimezoneCity.jsx:3:47)
  at Object.<anonymous> (imports/ui/components/mainLayout/MainLayout.jsx:6:47)
  at Object.<anonymous> (imports/ui/components/mainLayout/__tests__/MainLayout.test.js:3:19)
      at Generator.next (<anonymous>)
      at new Promise (<anonymous>)
      at Generator.next (<anonymous>)
      at <anonymous>

Please help me on this situation Thanks & best regards

[m-vdb]

that's crazy that this bug isn't fixed...

[ellenaua]

@m-vdb How can I reproduce it? Check pls this my repository, https://github.com/ellenaua/webpack-1/blob/master/src/index.js - can you change it in a way so that I get this error?

[m-vdb]

sorry @ellenaua I forgot to update my comment here. After spending two hours on this, I finally pinpointed the issue, and it was totally my fault. I was mocking moment explicitly (because I wanted to mock the timezone to UTC). Maybe it can help others if I post it here. Here was my code before:

//  test-setup.js
jest.mock('moment', () => {
  // UTC everywhere
  const moment = require.requireActual('moment');
  return moment.utc;
});

And I finally replaced that code with:

// test-setup.js
moment.tz.setDefault('UTC');

I honestly think that the initial issue report was similar to the one I had since jest auto mocks everything (what a pain...). If you agree, you can close this ✅

[osmyn]

I did something similar with mocking moment with moment-timezone:

    let diffMins = updateThreshold + 1;
    jest.mock('moment', () => {
      const mMoment = {
        diff: jest.fn(() => diffMins),
      };
      const fn = jest.fn(() => mMoment);
      fn.version = '2.24';
      fn.tz = jest.fn();
      fn.fn = jest.fn();
      return fn;
    });

[dtahoa]

sorry @ellenaua I forgot to update my comment here. After spending two hours on this, I finally pinpointed the issue, and it was totally my fault. I was mocking moment explicitly (because I wanted to mock the timezone to UTC). Maybe it can help others if I post it here. Here was my code before:

//  test-setup.js
jest.mock('moment', () => {
  // UTC everywhere
  const moment = require.requireActual('moment');
  return moment.utc;
});

And I finally replaced that code with:

// test-setup.js
moment.tz.setDefault('UTC');

I honestly think that the initial issue report was similar to the one I had since jest auto mocks everything (what a pain...). If you agree, you can close this ✅

// test-setup.js moment.tz.setDefault('UTC');

This works like a charm.

[testacode]

Doesn't work for me :( Tests passes but the log is angry.

moment: 2.26.0 moment-timezone: 0.5.3 (with data included)

edit: adding image + info

[dtahoa]

@testacode try to setup test like this: // test-setup.js moment.tz.setDefault('UTC');

[gilmoreorless]

I'm going to close this as it looks like the initial problem was solved. Since the answer appears to be "change the way Jest mocks are handled", there's nothing to be done in Moment Timezone itself.