对于上下文，我有一个名为delete_cars的控制器方法。在该方法中，我在Car的ActiveRecord::Collection上调用destroy_all。在destroy_all下面，我调用另一个方法get_car_nums_not_deleted_from_portal，如下所示：

def get_car_nums_not_deleted_from_portal(cars_to_be_deleted)
  reloaded_cars = cars_to_be_deleted.reload
  car_nums = reloaded_cars.car_numbers

  if reloaded_cars.any?
    puts "Something went wrong. The following cars were not deleted from the portal: #{car_nums.join(', ')}"
  end

  car_nums
end

这里，我检查在destroy_all事务期间是否有未删除的汽车，如果有，我就添加一条puts消息，还返回ActiveRecord::Collection是否有记录，以便后面的代码可以处理它。
我的一个特性测试的目标是模拟用户试图删除三辆选定的汽车，但其中一辆未能删除。当这种情况发生时，我会在页面上显示一个特定的通知，说明：

'Some selected cars have been successfully deleted from the portal, however, some have not. The '\
"following cars have not been deleted from the portal:\n\n#{some_car_numbers_go_here}"

当我的代码执行destroy_all时，如何强制一条记录失败，而不向我的Car模型添加额外的代码（以before_destroy或类似的形式）？我尝试过使用spy，但问题是，当它被创建时，它在DB中不是一条真实的的记录，因此我的查询：

cars_to_be_deleted = Car.where(id: params[:car_ids].split(',').collect { |id| id.to_i })

不包括在内。
要了解更多背景信息，请参阅以下测试代码：

context 'when at least one car is not deleted, but the rest are' do
  it "should display a message stating 'Some selected cars have been successfully...' and list out the cars that were not deleted" do
    expect(Car.count).to eq(100)
    visit bulk_edit_cars_path
    select(@location.name.upcase, from: 'Location')
    select(@track.name.upcase, from: 'Track')
    click_button("Search".upcase)

    find_field("cars_to_edit[#{Car.first.id}]").click
    find_field("cars_to_edit[#{Car.second.id}]").click
    find_field("cars_to_edit[#{Car.third.id}]").click
    click_button('Delete cars')

    cars_to_be_deleted = Car.where(id: Car.first(3).map(&:id)).ids
    click_button('Yes')

    expect(page).to have_text(
                      'Some selected cars have been successfully deleted from the portal, however, some have not. The '\
                      "following cars have not been deleted from the portal:\n\n#{@first_three_cars_car_numbers[0]}".upcase
                    )
    expect(Car.count).to eq(98)
    expect(Car.where(id: cars_to_be_deleted).length).to eq(1)
  end
end

任何帮助这将是非常感谢！它变得相当令人沮丧的哈哈。