cart.rb

def finalized?
  clicked_finalized? && (total_final_invoice.blank? || charged_on)
end

cart_spec.rb

describe Cart, 'when checking if a cart is finalized' do
  before(:each) do
    @cart = Cart.new
    @cart.stub!(:clicked_finalized?).and_return(true)
    @cart.stub!(:total_final_invoice).and_return("10.50")
  end
  
  it 'will not be finalized if the customer has not clicked finalized' do
    @cart.stub!(:clicked_finalized?).and_return(false)
    @cart.should_not be_finalized
  end
  
  it 'will not be finalized if the final price is more than zero and the customer has not been charged' do
    @cart.should_not be_finalized
  end
  
  it 'will be finalized if finalized is clicked and price is zero' do
    @cart.stub!(:total_final_invoice).and_return("")
    @cart.should be_finalized
  end
  
  it 'will be finalized if finalized is clicked and the customer is charged' do
    @cart.stub!(:charged_on).and_return(Time.now)
    @cart.should be_finalized
  end
end