fix timezone problem in strftime test (GitHub #6)

primary fix was to make the datetime UTC
however, this exposed an oddity (maybe a bug?) in Time::Piece:
-	see Dual-Life/Time-Piece#24 for a full explanation
so now we have our own `strftime` implementation which is not just a pass-through
-	now, for us, `->strftime("%s")` is always equivalent to `->epoch`
(note that my use of look-behind means you have to have at least Perl 5.005)
(but that doesn't seem like too much of a hardship)

Changes

@@ -4,6 +4,10 @@ Revision history for Date-Easy
 
 0.01_02   2016-05-22 01:48:55PDT-0700 America/Los_Angeles (TRIAL RELEASE)
 
+    [Bug Fixes]
+    * The "%s" format specifier now always returns the same value as the
+      epoch method, regardless of what the underlying implementation thinks
+
     [Interface Changes]
     * ::Date and ::Datetime now have accessors that follow the UI of
       DateTime rather than Time::Piece
@@ -12,6 +16,8 @@ Revision history for Date-Easy
     [Distro Fixes]
     * Fixed multiple cases of datetimes not matching due to clock rolling over
       github #4 (thx Slaven Rezić (SREZIC))
+    * Fixed `strftime` unit tests being locked to the author's timezone
+      github #6 (thx Slaven Rezić (SREZIC))
     * Fixed out-of-range tests on 32-bit machines
       github #3 (thx Slaven Rezić (SREZIC))
     * Fixed bug where List::Util might be too low a version during testing

lib/Date/Easy/Datetime.pm

@@ -151,7 +151,16 @@ sub epoch		{ shift->{impl}->epoch }
 sub day_of_week	{ shift->{impl}->day_of_week || 7 }						# change Sunday from 0 to 7
 sub quarter		{ int(shift->{impl}->_mon / 3) + 1 }					# calc quarter from (zero-based) month
 
-sub strftime	{ shift->{impl}->strftime(@_) }
+sub strftime
+{
+	my ($self, $format) = @_;
+	return $self->{impl}->strftime unless defined $format;
+
+	# Handle the %s format specifier ourselves because otherwise our users may get a nasty shock.
+	# See https://github.com/rjbs/Time-Piece/issues/24 for full details.
+	$format =~ s/(?<!%)%s/$self->epoch/eg;
+	return $self->{impl}->strftime($format);
+}
 
 
 ########################

t/format.t

@@ -4,9 +4,9 @@ use Date::Easy;
 
 
 # test date: 3 Feb 2001, 04:05:06
-my $dt = Date::Easy::Datetime->new(2001, 2, 3, 4, 5, 6);
+my $dt = Date::Easy::Datetime->new(UTC => 2001, 2, 3, 4, 5, 6);
 # epoch works out to:
-my $epoch = 981201906;
+my $epoch = 981173106;
 # dow is Sat
 
 
@@ -18,13 +18,19 @@ my %FORMATS =
 	"%Y/%m/%d %H:%M:%S"		=>	"2001/02/03 04:05:06",
 	"%l:%M:%S%p"			=>	" 4:05:06AM",
 	"%u"					=>	"6",
-	"%s"					=>	$epoch,
+	"%s %%s %s"				=>	"$epoch %s $epoch",
 );
 
 foreach (keys %FORMATS)
 {
 	is $dt->strftime($_), $FORMATS{$_}, "strftime format: $_";
 }
 
+# make sure I didn't bork the empty format call
+# note also that I avoid the locale-specific parts by using a regex with \w+
+my $str;
+warning_is { $str = $dt->strftime } undef, "no uninitialized warning on empty format";
+like $str, qr/^\w+, 03 \w+ 2001 04:05:06 UTC$/, "empty format produces default format";
+
 
 done_testing;