fix: allow user to reset timezone

packages/@internationalized/date/src/index.ts

@@ -63,6 +63,8 @@ export {
   today,
   getHoursInDay,
   getLocalTimeZone,
+  setLocalTimeZone,
+  resetLocalTimeZone,
   startOfMonth,
   startOfWeek,
   startOfYear,

packages/@internationalized/date/src/queries.ts

@@ -133,14 +133,23 @@ let localTimeZone: string | null = null;
 
 /** Returns the time zone identifier for the current user. */
 export function getLocalTimeZone(): string {
-  // TODO: invalidate this somehow?
   if (localTimeZone == null) {
     localTimeZone = new Intl.DateTimeFormat().resolvedOptions().timeZone;
   }
 
   return localTimeZone!;
 }
 
+/** Sets the time zone identifier for the current user. */
+export function setLocalTimeZone(timeZone: string): void {
+  localTimeZone = timeZone;
+}
+
+/** Resets the time zone identifier for the current user. */
+export function resetLocalTimeZone(): void {
+  localTimeZone = null;
+}
+
 /** Returns the first date of the month for the given date. */
 export function startOfMonth(date: ZonedDateTime): ZonedDateTime;
 export function startOfMonth(date: CalendarDateTime): CalendarDateTime;

packages/@internationalized/date/tests/queries.test.js

@@ -17,6 +17,7 @@ import {
   endOfYear,
   EthiopicCalendar,
   getDayOfWeek,
+  getLocalTimeZone,
   getMinimumDayInMonth,
   getMinimumMonthInYear,
   getWeeksInMonth,
@@ -31,6 +32,8 @@ import {
   maxDate,
   minDate,
   PersianCalendar,
+  resetLocalTimeZone,
+  setLocalTimeZone,
   startOfMonth,
   startOfWeek,
   startOfYear,
@@ -343,4 +346,15 @@ describe('queries', function () {
       expect(b.compare(a)).toBeGreaterThan(0);
     });
   });
+
+  describe('getLocalTimeZone', function () {
+    it('gets local time zone', function () {
+      const systemTimeZone = new Intl.DateTimeFormat().resolvedOptions().timeZone;
+      expect(getLocalTimeZone()).toBe(systemTimeZone);
+      setLocalTimeZone('America/Denver');
+      expect(getLocalTimeZone()).toBe('America/Denver');
+      resetLocalTimeZone();
+      expect(getLocalTimeZone()).toBe(systemTimeZone);
+    });
+  });
 });