public void TimeZoneTests()
{
var zonesToIgnore = new HashSet <string>();
foreach (var zone in TimeZoneInfo.GetSystemTimeZones().Where(t => !zonesToIgnore.Contains(t.Id)))
{
for (var i = 0; i < 4; i++)
{
var summer = new DateTime(2017 + i, 7, 1, 12, 0, 0, DateTimeKind.Unspecified);
var winter = new DateTime(2017 + i, 1, 1, 12, 0, 0, DateTimeKind.Unspecified);
var custZone = DateTimeZone.ById(zone.Id);
Assert.AreEqual(TimeZoneInfo.ConvertTime(summer, TimeZoneInfo.Utc, zone)
, DateTimeZone.ConvertTime(summer, DateTimeZone.Utc, custZone));
Assert.AreEqual(TimeZoneInfo.ConvertTime(summer, zone, TimeZoneInfo.Utc)
, DateTimeZone.ConvertTime(summer, custZone, DateTimeZone.Utc));
Assert.AreEqual(TimeZoneInfo.ConvertTime(winter, TimeZoneInfo.Utc, zone)
, DateTimeZone.ConvertTime(winter, DateTimeZone.Utc, custZone));
Assert.AreEqual(TimeZoneInfo.ConvertTime(winter, zone, TimeZoneInfo.Utc)
, DateTimeZone.ConvertTime(winter, custZone, DateTimeZone.Utc));
Assert.AreEqual(zone.GetUtcOffset(summer), custZone.GetUtcOffset(summer));
Assert.AreEqual(zone.GetUtcOffset(winter), custZone.GetUtcOffset(winter));
Assert.AreEqual(TimeZoneInfo.ConvertTime(new DateTimeOffset(summer, TimeSpan.FromHours(3)), zone)
, DateTimeZone.ConvertTime(new DateTimeOffset(summer, TimeSpan.FromHours(3)), custZone));
Assert.AreEqual(TimeZoneInfo.ConvertTime(new DateTimeOffset(winter, TimeSpan.FromHours(3)), zone)
, DateTimeZone.ConvertTime(new DateTimeOffset(winter, TimeSpan.FromHours(3)), custZone));
Assert.AreEqual(TimeZoneInfo.ConvertTime(new DateTimeOffset(summer, TimeSpan.FromHours(-7.5)), zone)
, DateTimeZone.ConvertTime(new DateTimeOffset(summer, TimeSpan.FromHours(-7.5)), custZone));
Assert.AreEqual(TimeZoneInfo.ConvertTime(new DateTimeOffset(winter, TimeSpan.FromHours(-7.5)), zone)
, DateTimeZone.ConvertTime(new DateTimeOffset(winter, TimeSpan.FromHours(-7.5)), custZone));
}
}
}