Ruby中的参数错误

Question

我有这样的代码

   require_relative 'die'
   describe Die do
   describe '#initialize' do
     it 'expects a single argument' do
        expect(Die.instance_method(:initialize).arity).to eq 1
     end
     it 'raises ArgumentError if sides are < 1' do
        expect {              #####line 10
            Die.new(-1)
        }.to raise_error(ArgumentError)
        expect {
            Die.new(0)
        }.to raise_error(ArgumentError)
     end
   end

我得到以下错误

> Die#initialize raises ArgumentError if sides are < 1
   Failure/Error: expect {
     expected ArgumentError but nothing was raised
   # ./spec.rb:10:in `block (3 levels) in <top (required)>'

我已经标记了第10行。有什么帮助我可以删除这个错误吗?

这是我的DIE类

    class Die
      def initialize(sides)
      end
      def num_of_sides()
      end
     def roll()
     end 
   end

Answer 1

把这行放到你的initialize方法中:

raise ArgumentError if sides < 1