Just happened to stumble upon the following article at caboo.se: Handy dynamic rspec tip.

I immediately found a way of simplifying a test case that involves testing that an ever increasing number of videos can be transcoded:

   1  require File.dirname(__FILE__) + '/helper'
   2  require File.dirname(__FILE__) + '/../lib/transcoder.rb'
   3  
   4  context "Transcoder" do
   5    
   6    Dir.glob('videos/*').each do |video|
   7      it "should support #{video}" do
   8        Transcoder.convert(video, "site/#{video}.flv")[:file_size].should > 0
   9      end
  10    end
  11  end

You can also use it to test model validations:

   1  require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')
   2  
   3  
   4  describe "Product" do
   5    @@valid_product_attributes = { 
   6        :name         => 'WTF',
   7        :description  => 'LOL',
   8        :price        => '10.0',
   9        :tax          => '22.0'  }
  10  
  11    
  12    before(:each) do
  13  
  14    end
  15  
  16    it "should create a new instance given valid attributes" do
  17      Product.create!(@@valid_product_attributes)
  18    end
  19    
  20    @@valid_product_attributes.each do |name, value|
  21      it "should not allow blank #{name}" do
  22        lambda do
  23          Product.create!(@@valid_product_attributes.except(name))
  24        end.should raise_error(ActiveRecord::RecordInvalid)
  25      end
  26    end
  27  end