I have an external command dep, that requires also a min version.
For example, xargs.

I've looked on cpan something to test that we a) have an external command available, and b) have at least that version, I can't find this Test::ExternalCommand like module.
Am I looking in the wrong place?

This has been my hack .. I know it's .. well.. hackish. 

#!/usr/bin/perl
use Test::Simple 'no_plan';
use File::Which;
# gnu xargs v 4.4 or more


ok( command_dependency( 'xargs', '4.2.27', 0 ), "have at least xargs 4
+.2.27");

ok( command_dependency( 'find', '4', 1 ), 'find 4');
ok( command_dependency( 'tar', '1.15' ), 'tar 1.15');


sub command_dependency {
   my ($name, $version, $debug)=@_;

   $^O=~/win/ and warn("Will not work on non posix systems.") and retu
+rn;

   $debug or local $SIG{__WARN__} = sub { 1 };



   no warnings;
   require File::Which;
   my $which = File::Which::which($name) or return;
   
   warn("Got which $name: $which");



   if (defined $version){

      # version have..
      my $_version;

      # get version output
      if ( system("$which --version") == 0 ){ # some cli respond to -v
+ instead of --version
         $_version = `$which --version`;
      }
      elsif ( system("$which -v") ==0 ){
         $_version = `$which -v`;
      }
      else { 
         warn("Command '$name' does not return version with -v or --ve
+rsion");
         return;
      }
      chomp $_version;
      warn("got '$_version'");

       

      # resolve to actual version string
      if( $_version=~/version\s+([\d\.]+)\b/ ){
         warn("match 1");
         $_version = $1;
      }
      elsif ( $_version=~/v\s*([\d\.]+)\b/ ){
         warn("match 2");
         $_version = $1;
      }
      elsif ( $_version=~/\b([\d\.]+)\b/ ){
         warn("match 3");
         $_version = $1;
      }
      else {
         warn("match missing, match into version output for '$name', d
+idn't resolve to actual version string in '$_version'");
         return;
      }
      
      # test against version argument to sub

      my @version = split(/\./, $version);
      my @_version = split(/\./, $_version);

      # only test as far as argument provided go
      my $count= scalar @version; # i know, there are quicker ways to 
+do this.. but..      
      # this is more clear for anybody viewing the code
      warn "count.. $count\n";
      my $index = 0;
      for ( 0 .. $count ){
         defined $version[$index] or next;
         if ( $version[$index] > $_version[$index] ){
         
            return 1; # obviously higher overall.
         }
         elsif ( $version[$index] < $_version[$index] ){
            return 0; # no high enough
         }
         $index++;
         # just high enough
         next;
      }
      # if we got here, have the version we want at least
      return 1;
   }

   # did not check version, but have command
   return 1;
}

[download]

I'm sure there's something out there that doesn't list look like it works, but actually works. (?) Any suggestions where that may be?

Would be useful for testing c libs etc. Maybe then, this should simply be coded into the makefile? They must have this down pat by now (?)

Code updated

In reply to test for non perl command dependency by leocharre

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