public void testBlockReference()
    {
        Filter filter = Filter.instance();
        filter.setActor(new Object());
        filter.addRules(Teacher.class, new Rules()
        {
            public boolean allow(Object actor, Object instance)
            {
                return false;
            }
        });

        Teacher mr_brown = new Teacher("Mr. Brown");
        ClassRoom english = new ClassRoom(mr_brown);
        assertNull(english.getTeacher());
        filter.clearActor();
        assertEquals(mr_brown, english.getTeacher();
    }