test wpic with JPEG

IO/Pnm/t/pic_16bit.t

@@ -13,26 +13,30 @@ $PDL::IO::Pic::debug=20;
 my $tmpdir = tempdir( CLEANUP => 1 );
 
 sub roundtrip {
-  my ($in, $file, $label, @extra) = @_;
+  local $Test::Builder::Level = $Test::Builder::Level + 1;
+  my ($in, $file, $label, $dimonly, @extra) = @_;
   $file = File::Spec->catfile($tmpdir, $file);
   $in->wpic($file);
   my $got = rpic($file, @extra);
-  ok all($in == $got), "$label image save+restore";
+  return is_deeply [$got->dims], [$in->dims] if $dimonly;
+  eval {ok all($in == $got), "$label image save+restore"};
+  is $@, '', "$label compare worked";
 }
 
 # test save/restore of 8-bit image
 roundtrip(my $x = sequence(16,16), 'byte_a.pnm', 'pnm byte');
 
-roundtrip($x, 'byte_a.png', 'png byte',
+roundtrip($x, 'byte_a.png', 'png byte', 0,
   $^O =~ /MSWin32/i ? {FORMAT => 'PNG'} : ()) if $can_png;
 
 # test save/restore of 16-bit image
-roundtrip(
-  my $a16 = sequence(256, 255)->ushort * 231,
+roundtrip(my $a16 = sequence(256, 255)->ushort * 231,
   'tushort_a16.pnm', 'pnm ushort',
 );
 
-roundtrip($a16, 'tushort_a16.png', 'png ushort',
+roundtrip($a16, 'tushort_a16.png', 'png ushort', 0,
   $^O =~ /MSWin32/i ? {FORMAT => 'PNG'} : ()) if $can_png;
 
+roundtrip(sequence(byte,3,32,24), 'byte_a.jpg', 'jpeg byte', 1, {FORMAT => 'JPEG'});
+
 done_testing;