package A::Class;

sub some_method
{
    my ($self, $object) = @_;
    die "Object is not what I expect"
        unless UNIVERSAL::isa( $object, 'Some::Class' );
    $object->some_other_method();
    $object->some_method_or_other();
}

##</code><code>##

use Test::More 'no_plan';

use Test::MockObject;
my $mock = Test::MockObject->new();

use_ok( 'A::Class' );
my $a = A::Class->new();
isa_ok( $a, 'A::Class' );

$mock->set_true( 'some_other_method' )
     ->set_true( 'some_method_or_other' );

$a->some_method( $mock );