Re: unpack and byteorder - tests fail on certain platforms

[davidrw]

From pack:

The integer formats s, S , i , I , l , L , j , and J are inherently non-portable between processors and operating systems because they obey the native byteorder and endianness.
...
If you want portable packed integers you can either use the formats n , N , v , and V , or you can use the > and < modifiers. These modifiers are only available as of perl 5.9.2. See also perlport.

[halley]

Agreed; a unit test of pack() and unpack() should not be concerned with the actual bytes of platform-dependent packings unless there is an independent, bug-free way of doing the packs and unpacks on that platform. The following would be good tests for the above formats:

$x = pack($format, $original);
ok($original == unpack($format, $x),
   'reversible unpack');

$x = external_platform_pack($format, $original);
ok($original == unpack($format, $x),
   'unpack from platform-specific source');

$x = pack($format, $original);
ok($original == external_platform_unpack($format, $x),
   'pack to platform-specific source');

Only the first one is devoid of platform-dependence. Of course, a diverse pool of $original value samples should be run.