Function firstTickInLocalDay

pkgs/core/src/_lib/test/tzOffsetTransitions.ts:44–53

(date: Date)

const MINUTE = 1000 * 60;

function firstTickInLocalDay(date: Date): Date {
  const dateNumber = date.getDate();
  let prev = date;
  let d = date;
  do {
    prev = d;
    d = new Date(d.getTime() - MINUTE);
  } while (dateNumber === d.getDate());
  return prev;
}

function fiveMinutesLater(date: Date): Date {
  return new Date(date.getTime() + 5 * MINUTE);