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POSIX/t/time.t: Add tests for DST changes

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Karl Williamson 2025-12-24 06:13:23 -07:00 committed by Karl Williamson
parent 0ff7fef53e
commit ecba154a51
1 changed files with 121 additions and 2 deletions
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121
ext/POSIX/t/time.t
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@ -9,7 +9,7 @@ use strict;
use Config;
use POSIX;
use Test::More tests => 31;
use Test::More tests => 49;
# For the first go to UTC to avoid DST issues around the world when testing. SUS3 says that
# null should get you UTC, but some environments want the explicit names.
@ -226,3 +226,122 @@ SKIP: {
is(strftime(undef, CORE::localtime), '', "strftime() works if format is undef");
like($warnings, qr/^Use of uninitialized value in subroutine entry /, "strftime(undef, ...) produces expected warning");
}
# Now check the transitioning between standard and daylight savings times. To
# do this requires setting a timezone. Unfortunately, timezone specification
# syntax differs incompatibly between systems. The older PST8PDT style
# prevails on Windows, but is being supplanted by "Europe/Paris" style
# elsewhere. Debian in particular requires a special package to be installed
# to correctly work with the old style. Worse, without the package, it still
# can recognize the syntax and correctly get right times that aren't at the
# edge of the transitions. khw tried the 2004 and 2025 spring forward times,
# and Debian sans-package was exactly 6 hours off the correct values.
# (The older style was U.S. centric, assuming everyone in the world with the
# same longitude obeyed the same rules; the new style can tailor the rules to
# the specific region affected.)
# Tue 01 Jul 2025 05:01:01 PM GMT. This is chosen as being in the middle of
# Daylight Savings Time. Below, we set locales, and verify that these
# actually worked by checking that the hour returned is the expected value.
my $reference_time = 1751389261;
my $new_names_all_passed = 0;
my $some_new_name_passed = 0;
SKIP: { # GH #23878; test that dst fall back works properly
my $skip_count = 9;
skip "No mktime()", $skip_count if $Config{d_mktime} ne 'define';
# Doing this ensures that Windows is expecting a different timezone than
# the one in the test. Hence, if the new-style name isn't recognized, the
# tests will be skipped. Otherwise, if the test happens to being run on a
# platform located in the Paris timezone, the check will happen to
# succeed even though the timezone change failed.
$ENV{TZ} = "PST8PDT";
tzset() if $has_tzset;
my $locale = "Europe/Paris";
$ENV{TZ} = $locale;
tzset() if $has_tzset;
skip "'$locale' not understood", $skip_count
if POSIX::strftime("%H", localtime($reference_time)) != 19;
my $t = 1761436800; # an hour before time should have changed
my @fall = (
[ -1, "2025-10-26 01:59:59+0200", "Chg -1 hr, 1 sec" ],
[ 0, "2025-10-26 02:00:00+0200", "Chg -1 hr, 0 sec" ],
[ 1, "2025-10-26 02:00:01+0200", "Chg -59 min, 59 sec" ],
[ 3599, "2025-10-26 02:59:59+0200", "Chg -1 sec" ],
[ 3600, "2025-10-26 02:00:00+0100", "At Paris DST fallback" ],
[ 3601, "2025-10-26 02:00:01+0100", "Chg +1 sec" ],
[ 7199, "2025-10-26 02:59:59+0100", "Chg +1 hr, 59m, 59s" ],
[ 7200, "2025-10-26 03:00:00+0100", "Chg +1 hr" ],
[ 7201, "2025-10-26 03:00:01+0100", "Chg +1 hr, 1 sec" ],
);
my $had_failure = 0;
for (my $i = 0; $i < @fall; $i++) {
if (is(POSIX::strftime("%F %T%z", localtime $t + $fall[$i][0]),
$fall[$i][1], $fall[$i][2]))
{
$some_new_name_passed = 1;
}
else {
$had_failure = 1
}
}
$new_names_all_passed = ! $had_failure;
}
SKIP: { # GH #23878: test that dst spring forward works properly.
my $skip_count = 9;
skip "No mktime()", $skip_count if $Config{d_mktime} ne 'define';
my $locale;
# For this group of tests, we use the old-style timezone names on systems
# that don't understand the new ones, and use the new ones on systems that
# do; this finesses the problem of some systems needing special packages
# to handle old names properly.
# The group of tests just before this one set this variable. If 'false'
# it means no new name worked, likely because they aren't understood, but
# also could be because of bugs.
if ($some_new_name_passed) {
skip "DST fall back didn't work; spring forward not tested",
$skip_count unless $new_names_all_passed;
$locale = "America/Los_Angeles";
}
else {
# Use a locale that MS narcissism should be able to handle
$locale = "PST8PDT";
}
$ENV{TZ} = $locale;
tzset() if $has_tzset;
# $reference_time is in the middle of summer, dst should be in effect.
skip "'$locale' not understood", $skip_count if
POSIX::strftime("%H", localtime($reference_time)) != 10;
my $t = 1741510800; # an hour before time should have changed
my @spring = (
[ -1, "2025-03-09 00:59:59-0800", "Chg -1 hr,-1 sec" ],
[ 0, "2025-03-09 01:00:00-0800", "Chg -1 hr, 0 sec" ],
[ 1, "2025-03-09 01:00:01-0800", "Chg -59 min,-59 sec" ],
[ 3599, "2025-03-09 01:59:59-0800", "Chg -1 sec" ],
[ 3600, "2025-03-09 03:00:00-0700",
"At Redmond DST spring forward" ],
[ 3601, "2025-03-09 03:00:01-0700", "Chg +1 sec" ],
[ 7199, "2025-03-09 03:59:59-0700", "Chg +1 hr, 59m,59s" ],
[ 7200, "2025-03-09 04:00:00-0700", "Chg +1 hr" ],
[ 7201, "2025-03-09 04:00:01-0700", "Chg +1 hr, 1 sec" ],
);
for (my $i = 0; $i < @spring; $i++) {
is(POSIX::strftime("%F %T%z", localtime $t + $spring[$i][0]),
$spring[$i][1], $spring[$i][2]);
}
}