[Ruby / Rspec] A tiny rspec example

01_.rspec

# Actual filename: .rspec

--format doc
--color

02_roll_spec.rb

# Actual filename: roll_spec.rb

require './roll'

describe Roll do
  context "with default sides" do
    let(:roll) { Roll.new }
  
    subject { roll }

    its(:result) { should_not > 6 }
    its(:result) { should_not < 1 }
    its(:sides)  { should == 6 }
  end

  context "with custom sides" do
    let(:sides) { 8 }
    let(:roll) { Roll.new sides }

    subject { roll }

    its(:result) { should_not > sides }
    its(:result) { should_not < 1 }
    its(:sides)  { should == sides }
  end

  context "with bonuses" do
    let(:bonus) { 4 }
    let(:roll) { Roll.new }
    let(:thrown_dice) { roll.throw_with_bonus bonus }
    let(:high) { roll.sides + bonus }
    let(:low) { 1 + bonus }

    subject { roll }

    its(:sides) { should == 6 }

    describe '#throw_with_bonus' do
      it "adds bonuses to roll results" do
        result = (thrown_dice >= low && thrown_dice <= high)

        result.should be_true
      end
    end
  end
end

03_roll.rb

# Actual filename: roll.rb

class Roll
  attr_accessor :sides

  def initialize sides = 6
    @sides ||= sides
  end

  def result
    rand(@sides) + 1
  end

  def throw_with_bonus bonus = 0
    result + bonus
  end
end