Question

我收到NoMethodError 对于我的代码，但我已经定义了它说缺少的add方法。我正在尝试将项添加到已存在的哈希。哈希是菜肴，我正在尝试使用add方法。

测试：

require 'menu'

describe Menu do

    it 'has a menu' do
        expect(subject.respond_to?(:dishes)).to be true
    end

    it 'displays dishes and prices' do
        expect(subject.dishes).to eq [
            { name: 'Burger', price: 10.95 },
            { name: 'Pizza', price: 14.00 },
            { name: 'Salad', price: 7.60 },
            { name: 'fries', price: 2.90 }
        ]
    end

    it 'can add dishes to it' do
        menu = Menu.new 
        menu.add_dish("Icecream", 4.80)
        expect(subject.dishes).to eq [
            { name: 'Burger', price: 10.95 },
            { name: 'Pizza', price: 14.00 },
            { name: 'Salad', price: 7.60 },
            { name: 'fries', price: 2.90 },
            { name: 'icecream', price: 4.80 }
        ]
    end
end

方法

class Menu
   def initialize
     @dishes = []
   end

   def dishes
     @dishes = [
        { name: 'Burger', price: 10.95  },
        { name: 'Pizza', price: 14.00 },
        { name: 'Salad', price: 7.60 },
        { name: 'fries', price: 2.90 }
     ]
   end

   def add_dish(name, price)
     @dishes << { name: name, price: price }
   end
end

谢谢

Answer 1

啊，我看到了你的问题。您需要初始化菜单。 Add不是静态方法。所以你需要类似的东西，

Menu.new.add(blah, blah)

看看：

Menu.add("Icecream", 4.80)

这种方法错了。它必须是：

Menu.new.add("Icecream", 4.80)

或者你需要类似的东西：

menu = Menu.new
menu.add("Icecream", 4.80)

Answer 2

Ryan-Neal Mes的答案解决了NoMethodError，但您的代码中还有许多其他问题。

你重复自己，你应该让你的代码变干（不要重复自己的原则）
虽然你想在菜单列表中添加一个哈希值，它自己是一个哈希列表，你强制需要调用add方法的对象以特定的顺序提供参数，而不是方法构造哈希，所以每次你需要调用它时，你需要返回它来查看参数的顺序。
dishes方法错误，因为每次调用它时，它都会将初始数组分配给@dishes变量。在这种情况下，add_dishes方法将无效，因为下次调用dishes方法时将删除添加的菜肴。
您的示例不具有表现力，因此如果测试没有通过，您无法从打印的消息中知道问题是什么。好吧，在这个小例子中这不是什么大问题，但在一个大的应用程序中，规格表达具有更高的价值。

这里的测试例子

require 'menu'

describe Menu do
  # every time you call the function dishes in an example
  # it will be declared and it will return this array
  let :dishes do
    [
      { name: 'Burger', price: 10.95 },
      { name: 'Pizza', price: 14.00 },
      { name: 'Salad', price: 7.60 },
      { name: 'fries', price: 2.90 }
    ]
  end

  # explicit definition of the subject
  subject { Menu.new }

  # a shorter yet more expressive version of
  # expect(subject.respond_to?(:dishes)).to be true
  it { is_expected.to respond_to(:dishes) }

  # You should always group the examples that test 
  # the same method
  describe '#dishes' do
    # it 'displays dishes and prices' do
    it 'returns the list of dishes' do
      expect(subject.dishes).to eq dishes
    end
  end

  describe "#add_dish" do
    # it 'can add dishes to it' do
    it "adds the given dish to the list of dishes" do
      new_dish = {name: 'salad', price: 4.0 }
      expect {
        subject.add_dish(new_dish)
      }.to change(subject.dishes, :count).by(1)
      expect(subject.dishes).to include new_dish
    end
  end
end

所以这里是类定义

class Menu
  # you don't need to declare the method dishes
  # since this is what attr_reader will do
  attr_reader :dishes

   def initialize
     # this will set the @dishes only once
     # but you code @dishes = [...] will return
     # the same list every time you call it and
     # all the dishes you add through the #add method
     # will be deleted.
     @dishes = [
        { name: 'Burger', price: 10.95  },
        { name: 'Pizza', price: 14.00 },
        { name: 'Salad', price: 7.60 },
        { name: 'fries', price: 2.90 }
     ]
   end

   # dish is a hash {name: '', price: ''} 
   def add_dish(dish)
     @dishes << dish
   end
end

所以现在运行rspec --format doc --color并查看消息的表达方式。

编写rspec测试以将项添加到哈希

2 个答案: