def METHOD_NAME(diagram, element_factory):
    cls = element_factory.create(UML.Class)
    cls_item1 = diagram.create(ClassItem, subject=cls)
    cls_item2 = diagram.create(ClassItem, subject=cls)
    buffer = copy_full({cls_item1, cls_item2})
    paste_link(buffer, diagram)
    assert len(list(diagram.get_all_items())) == 4
    assert len(element_factory.lselect(UML.Class)) == 1