public void GetAllZones() { // Note: in ID order. var zone1 = DateTimeZoneProviders.Tzdb["America/New_York"]; var zone2 = DateTimeZoneProviders.Tzdb["Europe/London"]; var zone3 = DateTimeZoneProviders.Tzdb["Europe/Paris"]; var provider = new FakeDateTimeZoneSource.Builder { zone1, zone2, zone3 }.Build().ToProvider(); CollectionAssert.AreEqual(new[] { zone1, zone2, zone3 }, provider.GetAllZones()); }