使用 find_by_id 获取 RSpec 中不存在的记录时引发 RecordNotFound

我在 products_controller_spec.rb 中编写了此规范，旨在测试在不存在的记录上调用 destroy 时的重定向：

it "deleting a non-existent product should redirect to the user's profile page with a flash error" do           
    delete :destroy, {:id => 9999}
    response.should redirect_to "/profile"
    flash[:error].should == I18n.t(:slideshow_was_not_deleted)
end

这是 products_controller.rb 中的控制器操作：

def destroy
  product = Product.find_by_id(params[:id])
  redirect_to "profile" if !product
  if product.destroy
    flash[:notice] = t(:slideshow_was_deleted)
    if current_user.admin? and product.user != current_user
      redirect_to :products, :notice => t(:slideshow_was_deleted)
    else
      redirect_to "/profile"
    end
  else
    if current_user.admin?
      redirect_to :products, :error => t(:slideshow_was_not_deleted)
    else
      redirect_to "/profile"
    end
  end
end

现在，我没想到规范会第一次通过，但我不明白为什么它会失败：

Failure/Error: delete :destroy, {:id => 9999}
 ActiveRecord::RecordNotFound:
   Couldn't find Product with id=9999

我的印象是 #find_by_id 不会在不存在的记录上返回 RecordNotFound 错误。那么为什么我会得到一个呢？提前致谢！

CanCan 引发 RecordNotFound 错误。它无法从控制器操作中进行救援（大概它发生在操作运行之前）。有两种方法可以解决它 -

1. 将规格更改为：

   it "deleting a non-existent product should result in a RecordNotFound Error" do         
     product_id = 9999
     expect { delete :destroy, {:id => product_id}}.to raise_error ActiveRecord::RecordNotFound
   end
   

或者， 2. 修补 CanCan像这样 https://github.com/ryanb/cancan/issues/43.

我不喜欢修补途径，所以我选择了选项 1。