test_unit.rb

module Test::Unit
  class TestCase

    def self.should(name, &block)
      test_name = "test_#{name.gsub(/\s+/, '_')}".to_sym
      defined = instance_method(test_name) rescue false
      raise "#{test_name} is already defined in #{self}" if defined
      if block_given?
        define_method(test_name, &block)
      else
        define_method(test_name) do
          flunk "No implementation provided for #{name}"
        end
      end
    end
  end
end

#now in use
class TestStuff < Test::Unit::TestCase
  def setup
    @foo = Klass.new
  end

  should "be of class Klass" do
    assert_equal Klass, @foo.class
  end

end