sets the timezone for your node.js process across all OSes

const setTZ = require('set-tz')
setTZ('UTC')
// that's it

It will even convert between operating systems

const setTZ = require('set-tz')
setTZ('America/New_York')

This will set timezone to America/New_York in non-Windows environments. In Windows environments, it will set the timezone to Eastern Standard Time (because Windows doesn't respect IANA timezones).

It is common to run all your tests in UTC no matter which timezone your computer is in. This ensures your snapshots will run fine on you CI and on your local machine no matter where you are located. If you need that, then you can use a shortcut:

  "jest": {
    "globalSetup": ['set-tz/utc']
  }

On windows, when you call setTZ() it effectively changes your whole OS timezone so beware-if you kill the process, you'll need to manually revert back after you're done-I am assuming you'r process is short-lived. If you don't kill your process, it will revert your original timezone back for you.

On all other OSes, it just sets process.env.TZ, so beware that the current process won't have the timezome set. Only it's children.