def METHOD_NAME(self):
    line = self.order.lines.all()[0]
    line.stockrecord.num_in_stock = 0
    line.stockrecord.save()
    order_history_page = self.app.get(
        reverse("customer:order", args=[self.order.number]), user=self.user
    )
    form = order_history_page.forms["order_form_%d" % self.order.id]
    form.submit()
    basket = Basket.open.get(owner=self.user)
    self.assertEqual(0, basket.all_lines().count())