ruby-on-rails - 如何测试一个 before_save 方法，包括与 rspec 的关联

Question

我在测试以下模型时遇到问题:

class Bill < ActiveRecord::Base
  belongs_to :consignee
  before_save :calc_rate

  def calc_rate
    self.chargeableweight = self.consignee.destination.rate * self.weight
  end
end

收货人模型:

class Consignee < ActiveRecord::Base
  belongs_to :destination
  has_many :bills
end

Controller 还没有被触及。

应用程序的行为是正确的(跟进问题:该解决方案是否存在任何性能问题？)- 但测试中断。

You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil.*

谢谢你的建议， 丹尼

更新:

这个账单测试使用 factory girl 中断:

describe Bill do

  it "should call the calc_rate method" do
    bill = Factory.build(:bill)
    bill.save!
    bill.should_receive(:calc_rate)
  end
end

当你没有预料到它时，你得到了一个 nil 对象!

工厂:

Factory.define :destination do |f|
  f.airport_code "JFK"
end

Factory.define :consignee do |f|
  ...
  f.association :destination
end


Factory.define :bill do |f|
  f.association :consignee
  f.weight 10
  f.chargeableweight 20.0
  f.after_create do |bill|
    bill.calc_rate
end

Answer 1

describe Consignee do
  it "should calculate the rate" do
    #pending
    #make sure this spec is passing first, so you know your calc_rate method is fine.
  end

  it "should accept calc_rate before save" do
    cosignee = mock("Consignee")
    consignee.should_receive(:calc_rate).and_return(2) # => stubbing your value
  end
end

我没有假脱机运行 Rails 应用程序来测试这段代码，但这应该让你接近。此外，假设列 chargeable_rate、weight 等是模型上的列，您不需要调用 self.如果没有可用的实例方法或该名称的变量，Ruby 将隐式期望 self 它将自动查找类方法。