Vehicle Class, Make == Instance Variable Dynamic

gistfile1.rb

#-------------------------------------
# this part just to run the specs
#
#
require 'rspec'
class Vehicle; end
# end
#-------------------------------------
#require_relative './vehicle'

class Automobile < Vehicle
  COMPARABLE_ATTRIBUTES = [:color, :make, :model, :year]
  COMPARABLE_ATTRIBUTES.each do |attr|
    attr_accessor attr
  end

  def initialize(hash)
    hash.each do |key, value|
      send("#{key}=", value) if self.respond_to?("#{key}=")
    end
  end
  
  def self.wheels
    4
  end

  def attribute_hash
    COMPARABLE_ATTRIBUTES.inject({}) {|hash, attr| hash[attr] = send(attr); hash}
    # I left the below commented out since "inject" is a complex method... it's basically doing the same as below
    #hash = {}
    #COMPARABLE_ATTRIBUTES.each {|attr| hash[attr] = send(attr)}
    #hash 
  end

  #this is brittle. It'll break as soon as other instance variables are added to the Automobile class.
  def ==(other) 
    self.attribute_hash == other.attribute_hash
  end
      
end


describe Automobile do
  let(:color) { "Red" }
  let(:make) { "Toyota" }
  let(:model) { "Camry" }
  let(:year) { 2012 }

  describe ":new" do
    subject { Automobile.new(color: color, make: make, model: model, year: year) }
    its(:color) {should eq(color) }
    its(:make) {should eq(make) }
    its(:model) {should eq(model) }
    its(:year) {should eq(year) }

    it "should not throw up if I send in something unexpected" do
    expect { 
      Automobile.new(paint_job: color) 
    }.to_not raise_error
    end
  end

  describe "#attribute_hash" do
    subject { Automobile.new(color: color, make: make, model: model, year: year) }
    it "should include all the attributes" do
      subject.attribute_hash.should eq ( {color: color, make: make, model: model, year: year} )
    end
  end

  describe "#==" do
    let(:auto_one){ Automobile.new(color: color, make: make, model: model, year: year) }
    let(:auto_two){ Automobile.new(color: color, make: make, model: model, year: year) }

    it "should be equal if color/make/model/year are the same" do
      auto_one.should eq(auto_two)
    end

    it "should not be equal if one differs" do
      auto_two.year = 2015
      auto_one.should_not eq(auto_two)
    end
  end
end

You can see my version here as a fork of this: https://gist.github.com/2775692/d4e7c9b678c19ac08c7c3fdbaf1e78f77b2f3a6e