frontend/test-mocha/common/util/format_date.js

import formatDate from '../../../js/common/util/format_date';

const assert = require('assert');

describe('formatDate', () => {
  const dateObj = new Date(
    2017, 10, 18,
    11, 12, 13, 1400,
  );

  it('Formats English dates', () => {
    assert.strictEqual(formatDate(dateObj, 'en'), 'November 18, 2017');
  });

  // Node only contains intl support for english formats. This test at least ensures
  // the fallback to a different locale
  it('Formats other dates', () => {
    assert.strictEqual(formatDate(dateObj, 'fr'), '2017 M11 18');
  });
});