exception後の挙動を確かめるrspec

rescue_spec.rb

require "rspec"

### target class

class Calculate
  def initialize
    # わかりやすい初期値をいれる
    @result = -9999
  end

  # 10を引数で割る
  def ten_division(number)
    @result = 10 / number
    @result
  end

  def last_result
    @result
  end
end

### spec

describe ".ten_division" do
  context "10を指定した場合" do
    let(:obj) { Calculate.new }
    subject { obj.ten_division(2) }
    it "last_resultで1が戻ってくる" do
      is_expected.to eq(5)
    end
  end

  context "0を指定した場合" do
    let(:obj) { Calculate.new }
    subject { obj.ten_division(0) }

    it "ZeroDivisionErrorがあがる" do
      expect { subject }.to raise_error(ZeroDivisionError)
    end

    it "last_resultで-9999が戻ってくる" do
      begin
        subject
      rescue
      end
      expect(obj.last_result).to eq(-9999)
    end
  end
end