A Simple Custom Test

package Test::Foo;
use base 'Exporter';
use strict;

use Test::Builder;
our @EXPORT = qw|foo_ok|;
sub foo_ok

{
  my $Test = Test::Builder->new;
  my $test = shift;
  my $name = shift || "test if '$test' eq 'foo'";
  my $ok;

  if( 'foo' eq $test ) {
    $ok = $Test->ok(0, $name);
    $Test->diag("'$test' does not equal 'foo'");
  }
  else {
    $ok = $Test->ok(1, $name);
  }

  return $ok;
}
1;