Mocking moment() and moment().format using jest

Question

I\'m unable to mock moment() or moment().format functions. I have states where, currentDateMoment and currentDateFormatted ar

Answer 1

You can mock Moment to return a specific date, then format don't have to be mocked.

jest.mock('moment', () => {
  return () => jest.requireActual('moment')('2020-01-01T00:00:00.000Z');
});

By doing so, any call to Moment() will always return a moment object with date set to 2020-01-01 00:00:00

Here is an example with a function that return the date of tomorrow and the test for this function.

const moment = require('moment');
const tomorrow = () => {
  const now = moment();
  return now.add(1, 'days');
};

describe('tomorrow', () => {
  it('should return the next day in a specific format', () => {
    const date = tomorrow().format('YYYY-MM-DD');
    expect(date).toEqual('2020-01-02');
  });
});