DT presentation comments

slide_10.rb

class Car
  def initialize(model, engine = ::Engine.new)
    @model = model
    @engine = engine
  end
  
  def running
    engine.running
  end
  
  def start
    engine.start
  end
  
  private
  
  attr_access :model, :engine
end

slide_12.rb

describe User do
  let(:user) { User.new }
  let(:nasty_external_library) { double(:nasty_external_library) }
  
  before do
    allow(::SomeNastyExternalLibrary).to receive(:new) { nasty_external_library }
    allow(nasty_external_library).to receive(:activated?) { true }  
  end
  
  describe "#ready_for_launch?" do
    expect(user.ready_for_launch?).to be_true
  end
end

class User
  def ready_for_launch?
    ::SomeNastyExternalLibrary.new.activated? 
  end
end

slide_9.rb

describe Car do
  let(:car) { Car.new("ford", engine) }
  let(:engine) { double(:engine) }
    
  describe "#start" do
    it "starts the engine" do
      expect(engine).to receive(:start)
      car.start
    end
  end
  
  describe "#running" do
    let(:running_status) { double(:running_status) }
    
    it "returns the engine running status" do
      allow(engine).to receive(:running) { running_status }
      expect(car.running).to eq(running_status)
    end  
  end
end