source: trunk/essentials/dev-lang/perl/lib/vars.t

#!./perl 

BEGIN {
    chdir 't' if -d 't';
    @INC = '../lib';
    $ENV{PERL5LIB} = '../lib';
}

$| = 1;

print "1..27\n";

# catch "used once" warnings
my @warns;
BEGIN { $SIG{__WARN__} = sub { push @warns, @_ }; $^W = 1 };

%x = ();
$y = 3;
@z = ();
$X::x = 13;

use vars qw($p @q %r *s &t $X::p);

my $e = !(grep /^Name "X::x" used only once: possible typo/, @warns) && 'not ';
print "${e}ok 1\n";
$e = !(grep /^Name "main::x" used only once: possible typo/, @warns) && 'not ';
print "${e}ok 2\n";
$e = !(grep /^Name "main::y" used only once: possible typo/, @warns) && 'not ';
print "${e}ok 3\n";
$e = !(grep /^Name "main::z" used only once: possible typo/, @warns) && 'not ';
print "${e}ok 4\n";
($e, @warns) = @warns != 4 && 'not ';
print "${e}ok 5\n";

# this is inside eval() to avoid creation of symbol table entries and
# to avoid "used once" warnings
eval <<'EOE';
$e = ! $main::{p} && 'not ';
print "${e}ok 6\n";
$e = ! *q{ARRAY} && 'not ';
print "${e}ok 7\n";
$e = ! *r{HASH} && 'not ';
print "${e}ok 8\n";
$e = ! $main::{s} && 'not ';
print "${e}ok 9\n";
$e = ! *t{CODE} && 'not ';
print "${e}ok 10\n";
$e = defined $X::{q} && 'not ';
print "${e}ok 11\n";
$e = ! $X::{p} && 'not ';
print "${e}ok 12\n";
EOE
$e = $@ && 'not ';
print "${e}ok 13\n";

eval q{use vars qw(@X::y !abc); $e = ! *X::y{ARRAY} && 'not '};
print "${e}ok 14\n";
$e = $@ !~ /^'!abc' is not a valid variable name/ && 'not ';
print "${e}ok 15\n";