test.rb

require 'active_support/all'

module SetupAndTeardown
  extend ActiveSupport::Concern

  included do
    class_attribute :callbacks
    self.callbacks = []
  end

  module ClassMethods
    def setup(&block)
      #self.callbacks ||= []
      callbacks << block
    end
  end

end

module Behavior
  def self.included(base)
    base.include SetupAndTeardown
  end
end

class TestCase
  include Behavior
end

class MyFirstTest < TestCase
  setup { puts "#{self}:C" }
end

class MyTest < TestCase
  setup { puts "#{self}:A" }
  setup { puts "#{self}:B" }

  def foo
    self.class.callbacks.each { |c| instance_eval(&c) }
  end
end

MyTest.new.foo