Show dates where Date::WeekOfYear gets the week number wrong

compare-weeks

#!/usr/local/bin/perl
#
# Compares the week numbers from DateTime and Date::WeekOfYear
# This shows the places where WeekOfYear gets it wrong.
#
use strict;
use warnings;
use DateTime;
use Date::WeekOfYear;
my $DAY_IN_SECONDS = 24 * 60 * 60;
my $time = time();

for (my $i = 0; $i < 1500; $i++) {
    my @tm = gmtime($time);
    my ($year, $month, $day) = @tm[5,4,3];
    $year += 1900;
    $month++;

    my $dt = DateTime->from_epoch(epoch => $time);
    my ($week_year, $week_number) = $dt->week;
    my $dt_week = sprintf("%.4d-W%.2d", $week_year, $week_number);

    my ($woy_week, $woy_year) = WeekOfYear($time);
    my $date    = $dt->strftime('%Y-%m-%d');
    my $woy = sprintf("%.4d-W%.2d", $woy_year, $woy_week);

    if ($woy ne $dt_week) {
        print "for $date,  epoch=$time, dt_week=$dt_week,  WeekOfYear=$woy\n";
    }

    $time -= $DAY_IN_SECONDS;
}