[racket-dev] Test results are slightly incomprehensible...

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Wed Sep 28 19:04:38 EDT 2011

At Wed, 28 Sep 2011 21:02:14 +0100, Paulo J. Matos wrote:
> Errors were:
> (Section (got expected (call)))
> ((date) ((638931660) Error (find-seconds 0 1 2 1 4 1990)))

After looking into this, I conclude that the test is faulty, but that
it also highlights a bug/limitation on Windows:

 * The test assumes that the current timezone had daylight saving time
   starting at what would have been 2:00am on April 4, 1990.

   The test will fail on your machine if your timezone is set to a
   place with no or different DST rules (i.e., different than the
   standard US timezones).

 * Windows gets it wrong. It thinks that US Mountain Time started
   daylight saving sometime in March ---- which is the right idea for
   the current DST calendar, but wrong for 1990.

   My guess is that timezone configuration in Windows cannot support
   different DST start-date rules for different years.

I'll adjust the test, though I don't yet have a better idea than just
removing it.

Posted on the dev mailing list.