use strict;
use Test::More tests => 7;

sub ungonk {
  local $_ = $_[0];
  if (/^(foobar:(?:(?!gonk).){1,5})gonk/) {
    return $1
  } else {
    return undef
  };
};

is ungonk('foobar:hellogonk'), 'foobar:hello';
is ungonk('foobar:gonk'), undef;
is ungonk('foobar:higonk'), 'foobar:hi';
is ungonk('foobar:helloworldgonk'), undef;
is ungonk('foobar:gonkgonk'), undef;
is ungonk('foobar:gonkogonk'), undef;
is ungonk('foobar:ogonkgonk'), 'foobar:o';