source: vendor/perl/5.8.8/lib/Tie/Scalar.t

#!./perl

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

# this must come before main, or tests will fail
package TieTest;

use Tie::Scalar;
use vars qw( @ISA );
@ISA = qw( Tie::Scalar );

sub new { 'Fooled you.' }

package main;

use vars qw( $flag );
use Test::More tests => 13;

use_ok( 'Tie::Scalar' );

# these are "abstract virtual" parent methods
for my $method qw( TIESCALAR FETCH STORE ) {
        eval { Tie::Scalar->$method() };
        like( $@, qr/doesn't define a $method/, "croaks on inherited $method()" );
}

# the default value is undef
my $scalar = Tie::StdScalar->TIESCALAR();
is( $$scalar, undef, 'used TIESCALAR, default value is still undef' );

# Tie::StdScalar redirects to TIESCALAR
$scalar = Tie::StdScalar->new();
is( $$scalar, undef, 'used new(), default value is still undef' );

# this approach should work as well
tie $scalar, 'Tie::StdScalar';
is( $$scalar, undef, 'tied a scalar, default value is undef' );

# first set, then read
$scalar = 'fetch me';
is( $scalar, 'fetch me', 'STORE() and FETCH() verified with one test!' );

# test DESTROY with an object that signals its destruction
{
        my $scalar = 'foo';
        tie $scalar, 'Tie::StdScalar', DestroyAction->new();
        ok( $scalar, 'tied once more' );
        is( $flag, undef, 'destroy flag not set' );
}

# $scalar out of scope, Tie::StdScalar::DESTROY() called, DestroyAction set flag
is( $flag, 1, 'and DESTROY() works' );

# we want some noise, and some way to capture it
use warnings;
my $warn;
local $SIG{__WARN__} = sub {
        $warn = $_[0];
};

# Tie::Scalar::TIEHANDLE should find and call TieTest::new and complain
is( tie( my $foo, 'TieTest'), 'Fooled you.', 'delegated to new()' );
like( $warn, qr/WARNING: calling TieTest->new/, 'caught warning fine' );

package DestroyAction;

sub new {
        bless( \(my $self), $_[0] );
}

sub DESTROY {
        $main::flag = 1;
}