使用 Mocha 测试关联方法

Question

我有一个带有 Order 和 Refund 模型的 Rails 应用程序。订单 has_many :refunds。一切都很好。我正在尝试为控制器中的退款逻辑编写功能测试。这是我现在拥有的：

test "should not process partial paypal refund for partially refunded order when refund total plus refund amount is greater than order total" do
    set_super_admin_login_credentials
    o = Order.new
    o.stubs({:id => 1234567, :source => "PayPal", :total => 39.95, :user => users(:dave)})
    Order.stubs(:find).with(1234567).returns(o)
    get :refund, {:order_id => 1234567}
    assert_equal o, assigns(:order)
    o.refunds.build.stubs({:amount => 1.0})
    o.refunds.build.stubs({:amount => 30.00})
    assert_raise do
        post :refund, {:order_id => 1234567, :refund_amount => 10.00}
    end
end

而在控制器中，退款方法是这样的：

def refund    
    @order = Order.find(params[:order_id])
    return if request.get?

    amount = params[:refund_amount].to_f
    raise "Cannot refund order for more than total" if (@order.refunds.sum(&:amount) + amount)
    # Do refund stuff
end

一些注意事项：

1. 我将 o.refunds.build 位基于 Ryan Bates' Railscast. 如果这不正确或不再相关，这是有用的信息。

2. 我看到很多关于如何实际执行sum 方法的相互矛盾的信息，有些使用&，有些没有。在script/console 中，& 爆炸了，但没有它，我得到了一个实际的总和。但是，在我的控制器中，如果我从 &:amount 切换到 :amount，我会收到以下消息：NoMethodError: undefined method+' for :amount:Symbol`

我觉得缺少一些概念性信息而不是某个地方的错误，所以我会感谢一些指针。

Answer 1

终于解决了问题。我将一个空关联存根为[]，而不是将它留给nil，让Rails 处理其他一些方法。所以，当我改变一个时，另一个会失败。智者的话：Enumerable#sum 和 ActiveRecord::Associations::AssociationCollection#sum 采用完全不同的参数。 :)

因此，通过将存根更改为在 sum 中删除 :refunds => [] 和 using a string for the field name，我让事情恢复正常。所以，这是上面代码的功能版本：

test "should not process partial paypal refund for partially refunded order when refund total plus refund amount is greater than order total" do
    set_super_admin_login_credentials
    o = Order.new
    o.stubs({:id => 1234567, :source => "PayPal", :total => 39.95, :user => users(:dave)})
    Order.stubs(:find).with(1234567).returns(o)
    get :refund, {:order_id => 1234567}
    assert_equal o, assigns(:order)
    o.refunds.build.stubs({:amount => 1.0})
    o.refunds.build.stubs({:amount => 30.00})
    assert_raise do
        post :refund, {:order_id => 1234567, :refund_amount => 10.00}
    end
end

def refund    
    @order = Order.find(params[:order_id])
    return if request.get?

    amount = params[:refund_amount].to_f
    raise "Cannot refund order for more than total" if (@order.refunds.sum('amount') + amount)
    # Do refund stuff
end