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t/005_order_disagreement.t  view on Meta::CPAN

use strict;
use warnings;

use Test::More tests => 1;

use Algorithm::C3;

=pod

This example is take from: http://www.python.org/2.3/mro.html

"Serious order disagreement" # From Guido
class O: pass
class X(O): pass
class Y(O): pass
class A(X,Y): pass
class B(Y,X): pass
try:
    class Z(A,B): pass #creates Z(A,B) in Python 2.2
except TypeError:
    pass # Z(A,B) cannot be created in Python 2.3

=cut

{
    package X;

    package Y;

    package XY;
    our @ISA = ('X', 'Y');

    package YX;
    our @ISA = ('Y', 'X');

    package Z;
    our @ISA = ('XY', 'YX');
}

eval {
    Algorithm::C3::merge('Z' => sub {
        no strict 'refs';
        @{$_[0] . '::ISA'};
    })
};
like($@, qr/^Inconsistent hierarchy/, '... got the right error with an inconsistent hierarchy');