nixpkgs/nixos/tests/timezone.nix

import ./make-test-python.nix (
  { pkgs, ... }:
  {
    name = "timezone";
    meta.maintainers = with pkgs.lib.maintainers; [ ];

    nodes = {
      node_eutz =
        { pkgs, ... }:
        {
          time.timeZone = "Europe/Amsterdam";
        };

      node_nulltz =
        { pkgs, ... }:
        {
          time.timeZone = null;
        };
    };

    testScript =
      { nodes, ... }:
      ''
        node_eutz.wait_for_unit("dbus.socket")

        with subtest("static - Ensure timezone change gives the correct result"):
            node_eutz.fail("timedatectl set-timezone Asia/Tokyo")
            date_result = node_eutz.succeed('date -d @0 "+%Y-%m-%d %H:%M:%S"')
            assert date_result == "1970-01-01 01:00:00\n", "Timezone seems to be wrong"

        node_nulltz.wait_for_unit("dbus.socket")

        with subtest("imperative - Ensure timezone defaults to UTC"):
            date_result = node_nulltz.succeed('date -d @0 "+%Y-%m-%d %H:%M:%S"')
            print(date_result)
            assert (
                date_result == "1970-01-01 00:00:00\n"
            ), "Timezone seems to be wrong (not UTC)"

        with subtest("imperative - Ensure timezone adjustment produces expected result"):
            node_nulltz.succeed("timedatectl set-timezone Asia/Tokyo")

            # Adjustment should be taken into account
            date_result = node_nulltz.succeed('date -d @0 "+%Y-%m-%d %H:%M:%S"')
            print(date_result)
            assert date_result == "1970-01-01 09:00:00\n", "Timezone was not adjusted"

        with subtest("imperative - Ensure timezone adjustment persists across reboot"):
            # Adjustment should persist across a reboot
            node_nulltz.shutdown()
            node_nulltz.wait_for_unit("dbus.socket")
            date_result = node_nulltz.succeed('date -d @0 "+%Y-%m-%d %H:%M:%S"')
            print(date_result)
            assert (
                date_result == "1970-01-01 09:00:00\n"
            ), "Timezone adjustment was not persisted"
      '';
  }
)