parcels.rb

class Parcel
  def initialize(weight, height, width, length)
    @weight = weight
    @height = height
    @width = width
    @length = length
    @dimensional_weight = (@length * @width * @height)/ 166
  end
  
  def dimensional_weight
    @dimensional_weight
  end 

  def cost_to_ship 
    if @weight > @dimensional_weight
      @weight * 5
    else
      @dimensional_weight * 5
    end
  end 
end

parcels_program.rb

require "./lib/parcels"

def main_menu
  puts "Please enter weight in pounds of package"
  weight = gets.to_i
  puts "Please enter height in inches"
  height = gets.to_i
  puts "Please enter width in inches"
  width = gets.to_i
  puts "Please enter length in inches"
  length = gets.to_i

  parcel = Parcel.new(weight, height, width, length)
  puts "The cost to ship your package is $#{parcel.cost_to_ship}."
end  

main_menu

parcels_spec.rb

require 'rspec'
require 'parcels'

describe Parcel do 
  it "initializes with a weight, height, width and length" do 
    test_parcel = Parcel.new(100, 4, 4, 4)
    test_parcel.should be_an_instance_of Parcel 
  end

  it "has a dimensional weight" do 
    test_parcel = Parcel.new(100, 10, 10, 10)
    test_parcel.dimensional_weight.should eq 6
  end

  it "takes the dimensions and weight of the parcel and calculates cost to ship" do
    test_parcel = Parcel.new(5,10,10,10)
    test_parcel.cost_to_ship.should eq 30
  end
end