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[2019-08] Fix time zone issue when jumping into DST (#17027)
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There is an issue with jumping into DST for some time zones when the incorrect date-time offset is returned for date-time in UTC (which comes from DateTime.Now). The fix is to just check if the incoming date-time is in UTC
Also I added set of tests for some time zones but they verify jumping into DST in general.

Fixes #16395

Backport of #16430
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@steveisok @akoeplinger
steveisok authored and akoeplinger committed Sep 25, 2019
1 parent 6a8aced commit c99adb9
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Showing 2 changed files with 259 additions and 2 deletions.
7 changes: 5 additions & 2 deletions mcs/class/corlib/System/TimeZoneInfo.cs
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Expand Up @@ -1216,10 +1216,13 @@ private bool TryGetTransitionOffset (DateTime dateTime, out TimeSpan offset, out
return false;
}

var isUtc = false;
if (dateTime.Kind != DateTimeKind.Utc) {
if (!TryAddTicks (date, -BaseUtcOffset.Ticks, out date, DateTimeKind.Utc))
return false;
}
} else
isUtc = true;


AdjustmentRule current = GetApplicableRule (date);
if (current != null) {
Expand All @@ -1231,7 +1234,7 @@ private bool TryGetTransitionOffset (DateTime dateTime, out TimeSpan offset, out
if (forOffset)
isDst = true;
offset = baseUtcOffset;
if (date >= new DateTime (tStart.Ticks + current.DaylightDelta.Ticks, DateTimeKind.Utc))
if (isUtc || (date >= new DateTime (tStart.Ticks + current.DaylightDelta.Ticks, DateTimeKind.Utc)))
{
offset += current.DaylightDelta;
isDst = true;
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254 changes: 254 additions & 0 deletions mcs/class/corlib/Test/System/TimeZoneInfoTest.cs
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Expand Up @@ -54,8 +54,11 @@ public static string MapTimeZoneId (string id)
return "New Zealand Standard Time";
case "Europe/Athens":
return "GTB Standard Time";
case "Europe/Chisinau":
return "E. Europe Standard Time";
case "US/Eastern":
return "Eastern Standard Time";
case "America/Chicago":
case "US/Central":
return "Central Standard Time";
case "US/Pacific":
Expand All @@ -64,18 +67,57 @@ public static string MapTimeZoneId (string id)
case "Australia/Melbourne":
return "AUS Eastern Standard Time";
case "Europe/Brussels":
case "Europe/Copenhagen":
case "Europe/Paris":
case "Europe/Madrid":
return "Romance Standard Time";
case "Africa/Kinshasa":
return "W. Central Africa Standard Time";
case "Europe/Rome":
case "Europe/Vatican":
case "Europe/Vienna":
case "Europe/Berlin":
case "Europe/Luxembourg":
case "Europe/Malta":
case "Europe/Monaco":
case "Europe/Amsterdam":
case "Europe/Oslo":
case "Europe/San_Marino":
return "W. Europe Standard Time";
case "Canada/Eastern":
return "Eastern Standard Time";
case "Asia/Tehran":
return "Iran Standard Time";
case "Europe/Guernsey":
case "Europe/Dublin":
case "Europe/Isle_of_Man":
case "Europe/Jersey":
case "Europe/Lisbon":
case "Europe/London":
return "GMT Standard Time";
case "America/Havana":
return "Cuba Standard Time";
case "America/Anchorage":
return "Alaskan Standard Time";
case "Atlantic/Azores":
return "Azores Standard Time";
case "Asia/Jerusalem":
return "Israel Standard Time";
case "Asia/Amman":
return "Jordan Standard Time";
case "Europe/Tirane":
case "Europe/Warsaw":
return "Central European Standard Time";
case "Europe/Sofia":
case "Europe/Tallinn":
case "Europe/Riga":
case "Europe/Vilnius":
case "Europe/Kiev":
return "FLE Standard Time";
case "Europe/Prague":
case "Europe/Budapest":
case "Europe/Bratislava":
return "Central Europe Standard Time";
default:
Assert.Fail ($"No mapping defined for zone id '{id}'");
return null;
Expand Down Expand Up @@ -482,6 +524,218 @@ public void Bug_9664 ()
Assert.AreEqual (new TimeSpan (0, 0, 0), tzi.GetUtcOffset (date));
#endif
}

[Test]
public void Bug_16395 ()
{
// Cuba, Havana (Cuba Standard Time): Jumps ahead at 12:00 AM on 3/8/2020 to 1:00 AM
CheckJumpingIntoDST ("America/Havana",
new DateTime (2020, 3, 8, 0, 0, 0), new DateTime (2020, 3, 8, 0, 30, 0), new DateTime (2020, 3, 8, 1, 0, 0),
new TimeSpan (-5, 0, 0), new TimeSpan (-4, 0, 0));

// US, Kansas City, MO (US Central Time): Jumps ahead at 2:00 AM on 3/8/2020 to 3:00 AM
CheckJumpingIntoDST ("America/Chicago",
new DateTime (2020, 3, 8, 2, 0, 0), new DateTime (2020, 3, 8, 2, 30, 0), new DateTime (2020, 3, 8, 3, 0, 0),
new TimeSpan (-6, 0, 0), new TimeSpan (-5, 0, 0));

// Anchorage, AK (Alaska Time): Jumps ahead at 2:00 AM on 3/8/2020 to 3:00 AM
CheckJumpingIntoDST ("America/Anchorage",
new DateTime (2020, 3, 8, 2, 0, 0), new DateTime (2020, 3, 8, 2, 30, 0), new DateTime (2020, 3, 8, 3, 0, 0),
new TimeSpan (-9, 0, 0), new TimeSpan (-8, 0, 0));

// Azores ST (Ponta Delgada, Portugal): Jumps ahead at 12:00 AM on 3/29/2020 to 1:00 AM
CheckJumpingIntoDST ("Atlantic/Azores",
new DateTime (2020, 3, 29, 0, 0, 0), new DateTime (2020, 3, 29, 0, 30, 0), new DateTime (2020, 3, 29, 1, 0, 0),
new TimeSpan (-1, 0, 0), new TimeSpan (0, 0, 0));

// Iran, Tehran (Iran ST): Jumps ahead at 12:00 AM on 3/21/2020 to 1:00 AM
CheckJumpingIntoDST ("Asia/Tehran",
new DateTime (2020, 3, 21, 0, 0, 0), new DateTime (2020, 3, 21, 0, 30, 0), new DateTime (2020, 3, 21, 1, 0, 0),
new TimeSpan (3, 30, 0), new TimeSpan (4, 30, 0));

// Israel, Jerusalem (Israel ST): Jumps ahead at 2:00 AM on 3/27/2020 to 3:00 AM
CheckJumpingIntoDST ("Asia/Jerusalem",
new DateTime (2020, 3, 27, 2, 0, 0), new DateTime (2020, 3, 27, 2, 30, 0), new DateTime (2020, 3, 27, 3, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// Jordan, Amman (Eastern European ST): Jumps ahead at 12:00 AM on 3/27/2020 to 1:00 AM
CheckJumpingIntoDST ("Asia/Amman",
new DateTime (2020, 3, 27, 0, 0, 0), new DateTime (2020, 3, 27, 0, 30, 0), new DateTime (2020, 3, 27, 1, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// Albania, Tirana (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Tirane",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Austria, Vienna (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Vienna",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Belgium, Brussels (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Brussels",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Bulgaria, Sofia (Eastern European ST): Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
CheckJumpingIntoDST ("Europe/Sofia",
new DateTime (2020, 3, 29, 3, 0, 0), new DateTime (2020, 3, 29, 3, 30, 0), new DateTime (2020, 3, 29, 4, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// Czechia, Prague (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Prague",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Denmark, Copenhagen (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Copenhagen",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Estonia, Tallinn (Eastern European ST): Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
CheckJumpingIntoDST ("Europe/Tallinn",
new DateTime (2020, 3, 29, 3, 0, 0), new DateTime (2020, 3, 29, 3, 30, 0), new DateTime (2020, 3, 29, 4, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// France, Paris (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Paris",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Germany, Berlin (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Berlin",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Greece, Athens (Eastern European ST): Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
CheckJumpingIntoDST ("Europe/Athens",
new DateTime (2020, 3, 29, 3, 0, 0), new DateTime (2020, 3, 29, 3, 30, 0), new DateTime (2020, 3, 29, 4, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// Guernsey (UK) Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
CheckJumpingIntoDST ("Europe/Guernsey",
new DateTime (2020, 3, 29, 1, 0, 0), new DateTime (2020, 3, 29, 1, 30, 0), new DateTime (2020, 3, 29, 2, 0, 0),
new TimeSpan (0, 0, 0), new TimeSpan (1, 0, 0));

// Holy See, Vatican City (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Vatican",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Hungary, Budapest (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Budapest",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// // Ireland, Dublin (Greenwich Mean Time -> Irish Standard Time): Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
// CheckJumpingIntoDST ("Europe/Dublin",
// new DateTime (2020, 3, 29, 1, 0, 0), new DateTime (2020, 3, 29, 1, 30, 0), new DateTime (2020, 3, 29, 2, 0, 0),
// new TimeSpan (0, 0, 0), new TimeSpan (1, 0, 0));

// UK, Douglas, Isle of Man (GMT+1:00): Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
CheckJumpingIntoDST ("Europe/Isle_of_Man",
new DateTime (2020, 3, 29, 1, 0, 0), new DateTime (2020, 3, 29, 1, 30, 0), new DateTime (2020, 3, 29, 2, 0, 0),
new TimeSpan (0, 0, 0), new TimeSpan (1, 0, 0));

// Italy, Rome (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Rome",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Jersey (UK): Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
CheckJumpingIntoDST ("Europe/Jersey",
new DateTime (2020, 3, 29, 1, 0, 0), new DateTime (2020, 3, 29, 1, 30, 0), new DateTime (2020, 3, 29, 2, 0, 0),
new TimeSpan (0, 0, 0), new TimeSpan (1, 0, 0));

// Latvia, Riga (Eastern European ST): Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
CheckJumpingIntoDST ("Europe/Riga",
new DateTime (2020, 3, 29, 3, 0, 0), new DateTime (2020, 3, 29, 3, 30, 0), new DateTime (2020, 3, 29, 4, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// Lithuania, Vilnius (Eastern European ST): Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
CheckJumpingIntoDST ("Europe/Vilnius",
new DateTime (2020, 3, 29, 3, 0, 0), new DateTime (2020, 3, 29, 3, 30, 0), new DateTime (2020, 3, 29, 4, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// Luxembourg, Luxembourg (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Luxembourg",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Malta, Valletta (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Malta",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Moldova, Chişinău (Eastern European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Chisinau",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// Monaco, Monaco (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Monaco",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Netherlands, Amsterdam (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Amsterdam",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Norway, Oslo (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Oslo",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Poland, Warsaw (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Warsaw",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Portugal, Lisbon (Western European ST): Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
CheckJumpingIntoDST ("Europe/Lisbon",
new DateTime (2020, 3, 29, 1, 0, 0), new DateTime (2020, 3, 29, 1, 30, 0), new DateTime (2020, 3, 29, 2, 0, 0),
new TimeSpan (0, 0, 0), new TimeSpan (1, 0, 0));

// San Marino, San Marino (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/San_Marino",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Slovakia, Bratislava (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Bratislava",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Spain, Madrid (Central European ST): Jumps ahead at 2:00 AM on 3/29/2020 to 3:00 AM
CheckJumpingIntoDST ("Europe/Madrid",
new DateTime (2020, 3, 29, 2, 0, 0), new DateTime (2020, 3, 29, 2, 30, 0), new DateTime (2020, 3, 29, 3, 0, 0),
new TimeSpan (1, 0, 0), new TimeSpan (2, 0, 0));

// Ukraine, Kiev (Eastern European ST): Jumps ahead at 3:00 AM on 3/29/2020 to 4:00 AM
CheckJumpingIntoDST ("Europe/Kiev",
new DateTime (2020, 3, 29, 3, 0, 0), new DateTime (2020, 3, 29, 3, 30, 0), new DateTime (2020, 3, 29, 4, 0, 0),
new TimeSpan (2, 0, 0), new TimeSpan (3, 0, 0));

// United Kingdom, London (British ST): Jumps ahead at 1:00 AM on 3/29/2020 to 2:00 AM
CheckJumpingIntoDST ("Europe/London",
new DateTime (2020, 3, 29, 1, 0, 0), new DateTime (2020, 3, 29, 1, 30, 0), new DateTime (2020, 3, 29, 2, 0, 0),
new TimeSpan (0, 0, 0), new TimeSpan (1, 0, 0));
}

void CheckJumpingIntoDST (string tzId, DateTime dstDeltaStart, DateTime inDstDelta, DateTime dstDeltaEnd, TimeSpan baseOffset, TimeSpan dstOffset)
{
var tzi = TimeZoneInfo.FindSystemTimeZoneById (MapTimeZoneId (tzId));
Assert.IsFalse (tzi.IsDaylightSavingTime (dstDeltaStart), $"{tzId}: #1");
Assert.AreEqual (baseOffset, tzi.GetUtcOffset (dstDeltaStart), $"{tzId}: #2");

Assert.IsFalse (tzi.IsDaylightSavingTime (inDstDelta), $"{tzId}: #3");
Assert.AreEqual (baseOffset, tzi.GetUtcOffset (inDstDelta), $"{tzId}: #4");

Assert.IsTrue (tzi.IsDaylightSavingTime (dstDeltaEnd), $"{tzId}: #5");
Assert.AreEqual (dstOffset, tzi.GetUtcOffset (dstDeltaEnd), $"{tzId}: #6");
}
}

[TestFixture]
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