uuse strict;
use warnings;
no strict 'vars';

use Test::More tests => 3;

sub var_exists {
   my ($var) = @_;
   return defined ${substr $var, 1};
}

{
   no warnings 'once';
   $var1 = 'a';
   $var2 = undef;
   @var3 = qw( a b c );
}

ok(var_exists('$var1'),  'var1');
ok(var_exists('$var2'),  'var2');
ok(!var_exists('$var3'), 'var3');

##</code><code>##

1..3
ok 1 - var1
not ok 2 - var2
#   Failed test 'var2'
#   at a.pl line 20.
ok 3 - var3
# Looks like you failed 1 test of 3.