[pywin32-checkins] /hgroot/pywin32/pywin32: Corrected error in the sign on TimeZone...

[<pyw...@li...>]

changeset 085048997feb in /hgroot/pywin32/pywin32
details: http://pywin32.hg.sourceforge.net/hgweb/pywin32/pywin32/hgroot/pywin32/pywin32?cmd=changeset;node=085048997feb
summary: Corrected error in the sign on TimeZoneInfo.dst(). The incorrect sign was on the .dst() value, but the mistake was masked because utcoffset again negated the value. Thanks to Brian Matthews for discovering the bug, providing a detailed bug report to reproduce the error, and for suggesting fixes in #3523104.

diffstat:

 win32/Lib/win32timezone.py |  84 +++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 79 insertions(+), 5 deletions(-)

diffs (115 lines):

diff -r bb81eda78987 -r 085048997feb win32/Lib/win32timezone.py
--- a/win32/Lib/win32timezone.py	Mon Apr 30 17:50:11 2012 +1000
+++ b/win32/Lib/win32timezone.py	Fri May 04 20:11:44 2012 -0400
@@ -6,9 +6,6 @@
 registry for time zone information.  The time zone names are dependent
 on the registry entries defined by the operating system.
 
-	Currently, this module only supports the Windows NT line of products
-and not Windows 95/98/Me.
-
 	This module may be tested using the doctest module.
 
 	Written by Jason R. Coombs (ja...@ja...).
@@ -149,6 +146,83 @@
 This test helps ensure language support for unicode characters
 >>> x = TIME_ZONE_INFORMATION(0, u'français')
 
+
+Test conversion from one time zone to another at a DST boundary
+===============================================================
+
+>>> tz_hi = TimeZoneInfo('Hawaiian Standard Time')
+>>> tz_pac = TimeZoneInfo('Pacific Standard Time')
+>>> time_before = datetime.datetime(2011, 11, 5, 15, 59, 59, tzinfo=tz_hi)
+>>> tz_hi.utcoffset(time_before)
+datetime.timedelta(-1, 50400)
+>>> tz_hi.dst(time_before)
+datetime.timedelta(0)
+
+Hawaii doesn't need dynamic TZ info
+>>> getattr(tz_hi, 'dynamicInfo', None)
+
+Here's a time that gave some trouble as reported in #3523104
+because one minute later, the equivalent UTC time changes from DST
+in the U.S.
+>>> dt_hi = datetime.datetime(2011, 11, 5, 15, 59, 59, 0, tzinfo=tz_hi)
+>>> dt_hi.timetuple()
+time.struct_time(tm_year=2011, tm_mon=11, tm_mday=5, tm_hour=15, tm_min=59, tm_sec=59, tm_wday=5, tm_yday=309, tm_isdst=0)
+>>> dt_hi.utctimetuple()
+time.struct_time(tm_year=2011, tm_mon=11, tm_mday=6, tm_hour=1, tm_min=59, tm_sec=59, tm_wday=6, tm_yday=310, tm_isdst=0)
+
+Convert the time to pacific time.
+>>> dt_pac = dt_hi.astimezone(tz_pac)
+>>> dt_pac.timetuple()
+time.struct_time(tm_year=2011, tm_mon=11, tm_mday=5, tm_hour=18, tm_min=59, tm_sec=59, tm_wday=5, tm_yday=309, tm_isdst=1)
+
+Notice that the UTC time is almost 2am.
+>>> dt_pac.utctimetuple()
+time.struct_time(tm_year=2011, tm_mon=11, tm_mday=6, tm_hour=1, tm_min=59, tm_sec=59, tm_wday=6, tm_yday=310, tm_isdst=0)
+
+Now do the same tests one minute later in Hawaii.
+>>> time_after = datetime.datetime(2011, 11, 5, 16, 0, 0, 0, tzinfo=tz_hi)
+>>> tz_hi.utcoffset(time_after)
+datetime.timedelta(-1, 50400)
+>>> tz_hi.dst(time_before)
+datetime.timedelta(0)
+
+>>> dt_hi = datetime.datetime(2011, 11, 5, 16, 0, 0, 0, tzinfo=tz_hi)
+>>> print dt_hi.timetuple()
+time.struct_time(tm_year=2011, tm_mon=11, tm_mday=5, tm_hour=16, tm_min=0, tm_sec=0, tm_wday=5, tm_yday=309, tm_isdst=0)
+>>> print dt_hi.utctimetuple()
+time.struct_time(tm_year=2011, tm_mon=11, tm_mday=6, tm_hour=2, tm_min=0, tm_sec=0, tm_wday=6, tm_yday=310, tm_isdst=0)
+
+According to the docs, this is what astimezone does.
+>>> utc = (dt_hi - dt_hi.utcoffset()).replace(tzinfo=tz_pac)
+>>> utc
+datetime.datetime(2011, 11, 6, 2, 0, tzinfo=TimeZoneInfo('Pacific Standard Time'))
+>>> tz_pac.fromutc(utc) == dt_hi.astimezone(tz_pac)
+True
+>>> tz_pac.fromutc(utc)
+datetime.datetime(2011, 11, 5, 19, 0, tzinfo=TimeZoneInfo('Pacific Standard Time'))
+
+Make sure the converted time is correct.
+>>> dt_pac = dt_hi.astimezone(tz_pac)
+>>> dt_pac.timetuple()
+time.struct_time(tm_year=2011, tm_mon=11, tm_mday=5, tm_hour=19, tm_min=0, tm_sec=0, tm_wday=5, tm_yday=309, tm_isdst=1)
+>>> dt_pac.utctimetuple()
+time.struct_time(tm_year=2011, tm_mon=11, tm_mday=6, tm_hour=2, tm_min=0, tm_sec=0, tm_wday=6, tm_yday=310, tm_isdst=0)
+
+Check some internal methods
+>>> tz_pac._getStandardBias(datetime.datetime(2011, 1, 1))
+datetime.timedelta(0, 28800)
+>>> tz_pac._getDaylightBias(datetime.datetime(2011, 1, 1))
+datetime.timedelta(0, 25200)
+
+Test the offsets
+>>> offset = tz_pac.utcoffset(datetime.datetime(2011, 11, 6, 2, 0))
+>>> offset == datetime.timedelta(hours=-8)
+True
+>>> dst_offset = tz_pac.dst(datetime.datetime(2011, 11, 6, 2, 0) + offset)
+>>> dst_offset == datetime.timedelta(hours=1)
+True
+>>> (offset + dst_offset) == datetime.timedelta(hours=-7)
+True
 """
 from __future__ import generators
 
@@ -518,7 +592,7 @@
 		"Calculates the utcoffset according to the datetime.tzinfo spec"
 		if dt is None: return
 		winInfo = self.getWinInfo(dt.year)
-		return -(winInfo.bias + self.dst(dt))
+		return -winInfo.bias + self.dst(dt)
 
 	def dst(self, dt):
 		"Calculates the daylight savings offset according to the datetime.tzinfo spec"
@@ -528,7 +602,7 @@
 			result = winInfo.daylight_bias
 		else:
 			result = winInfo.standard_bias
-		return result
+		return -result
 
 	def _inDaylightSavings(self, dt):
 		try: