memoization test

class Parser
  def errors
    @errors ||= []
  end
end

describe Parser do
  describe '#errors' do
    it "is an empty list" do
      subject.errors.should == []
    end
    
    it "always returns the same list" do
      errors = subject.errors
      subject.errors.should equal errors # tests that they're the same object
    end
  end
end