I'm running into an issue while testing two functions that convert ISO and Epoch timestamp to the client timezone. The tests are passing but I'm trying to modify them so we don't have to keep changing them based on Daylight time.

I added a bit of code to obtain the timezone abbreviation using Date() and toLocaleTimeString() and it works, except it fails in the CI/CD pipeline as the server returns UTC time. Even though, I'm adding options to specifically set the zone to America/Chicago, the server doesn't seem to recognize them.

describe('convertISO8601ToClientTimezone', () => {
  const timestamp = '2021-04-08T19:15:42.410506Z';
  const zoneAbbr = new Date(timestamp)
    .toLocaleTimeString('en-us', { timeZone: "America/Chicago", timeZoneName: 'short' })
    .split(' ')[2];

  it('should take ISO-8601 return date formatted string of local timezone offset accordingly', () => {
    expect(convertISO8601ToClientTimezone(timestamp)).toEqual(
      `April 8th 2021, 2:15:42 PM ${zoneAbbr}`
    );
  });
});

describe('convertEpochTimestampToClientTimezone', () => {
  const timestamp = 1617909517024179200; // epoch in nanoseconds
  const zoneAbbr = new Date(timestamp / 100000)
    .toLocaleTimeString('en-us', { timeZoneName: 'short' })
    .split(' ')[2];

  it('should take epoch timestamp and return date formatted string of local timezone offset accordingly', () => {
    expect(convertEpochTimestampToClientTimezone(timestamp)).toEqual(
      `April 8th 2021, 2:18:37 PM ${zoneAbbr}`
    );
  });
});

Is there a better way to get the timezone abbreviation for America/Chicago based on a given timestamp?

I'm also using the Moment library but I'm struggling to figure out how get the value needed from the mock fn. And actually, I'm not sure that would be the recommended approach here but I'm pretty new to Jest.