Demonstration of why private methods are problematic for specing, and also potentially a design smell, for discusion on rubyparley

1. code.rb

class Product
  attr_accessible :price
  attr_accessible :name

  def long_listing
    "The price of #{name} is #{human_price}"
  end
  
  def short_listing
    "#{name}: #{human_price}"
  end

private

  def human_price
    if price.nil?
      p = 0
    else
      p = price
    end

    number_to_currency(p, unit: '$')  
  end

end

2. spec.rb

describe Product
  let(:product) = Product.new
  describe "listings" do
    before do
      product.stub(:name){"The Name"}
      product.stub(:human_price){"$1.23"}
    end
    describe "#long_listing" do
      specify{product.long_listing.should eq("The price of The Name is $1.23")}
    end
    describe "#short_listing" do
      specify{product.short_listing.should eq("The Name: $1.23")}
    end
  end
  
  ## Can't actually do this spec, because the method is private!
  describe "#human_price" do
    subject{product.human_price}
    context "when the price is nil" do
      it{should eq "$0.00" }
    end
    context "when the price is present" do
      before{product.stub(:price){1.23}}
      it{should eq "$1.23" }
    end
  end

end