Tdd work shop

closed_range.rb

class ClosedRange
  attr_reader :lower_endpoint, :upper_endpoint

  def initialize(lower_endpoint, upper_endpoint)
    raise IllegalRangeError if lower_endpoint > upper_endpoint

    @lower_endpoint = lower_endpoint
    @upper_endpoint = upper_endpoint
  end

  def to_s
   "[#{lower_endpoint},#{upper_endpoint}]"
  end

  def include?(num)
    (@lower_endpoint..@upper_endpoint).include?(num)
  end

  def ==(other_range)
    @lower_endpoint == other_range.lower_endpoint && @upper_endpoint == other_range.upper_endpoint
  end

  def contain?(range)
    self.lower_endpoint <= range.lower_endpoint && range.lower_endpoint <= self.upper_endpoint
  end
end

class IllegalRangeError < ArgumentError ;end

closed_range_spec.rb

require 'spec_helper'

describe '整数閉区間を示す' do
  context '整数閉区間3-8' do
    let(:range) { ClosedRange.new(3, 8) }
    it '下端点3を持つ' do
      expect(range.lower_endpoint).to eq(3)
    end

    it '上端点8を持つ' do
      expect(range.upper_endpoint).to eq(8)
    end

    it '文字列表現は"[3,8]"' do
      expect(range.to_s).to eq("[3,8]")
    end

    describe '数値を含む・含まない' do
      it '2を含まない' do
        expect(range.include?(3)).to be_truthy
      end

      it '3を含む' do
        expect(range.include?(3)).to be_truthy
      end

      it '6を含む' do
        expect(range.include?(6)).to be_truthy
      end

      it '8を含む' do
        expect(range.include?(6)).to be_truthy
      end

      it '9を含まない' do
        expect(range.include?(9)).to be_falsey
      end
    end

    describe '等価判定' do
      it '3-8と等価である' do
        other_range = ClosedRange.new(3, 8)
        expect(range == other_range).to be_truthy
      end

      it '3-9と等価である' do
        other_range = ClosedRange.new(3, 9)
        expect(range == other_range).to be_falsey
      end
    end

    describe '包含判定' do
      it '4-7を包含する' do
        other_range = ClosedRange.new(4, 7)
        expect(range.contain?(other_range)).to be_truthy
      end

      it '2-7を包含しない' do
        other_range = ClosedRange.new(2, 7)
        expect(range.contain?(other_range)).to be_falsey
      end
    end
  end

  context '整数閉区間4-9' do
    let(:range) { ClosedRange.new(4, 9) }
    it '下端点4を持つ' do
      expect(range.lower_endpoint).to eq(4)
    end

    it '上端点9を持つ' do
      expect(range.upper_endpoint).to eq(9)
    end

    it '文字列表現は"[4,9]"' do
      expect(range.to_s).to eq("[4,9]")
    end

    describe '数値を含む・含まない' do
      it '3を含まない' do
        expect(range.include?(3)).to be_falsey
      end

      it '4を含む' do
        expect(range.include?(4)).to be_truthy
      end

      it '9を含む' do
        expect(range.include?(9)).to be_truthy
      end

      it '10を含まない' do
        expect(range.include?(10)).to be_falsey
      end
    end
  end

  context '整数閉区間8-3' do
    let(:range) { ClosedRange.new(8, 3) }
    it '上端点より下端点が大きい閉区間を作ることはできない' do
      expect{range}.to raise_exception(IllegalRangeError)
    end
  end
end