问如何获取RSpec的共享示例，如Ruby Test::Unit中的行为？

EN

require 'active_support/concern'

module SharedTests
  extend ActiveSupport::Concern

  included do

    # This way, test name can be a string :)
    test 'banana banana banana' do
      assert true
    end

  end
end

module SharedTests
  def shared_test_for(test_name, &block)
    @@shared_tests ||= {}
    @@shared_tests[test_name] = block
  end

  def shared_test(test_name, scenario, *args)
    define_method "test_#{test_name}_for_#{scenario}" do
      instance_exec *args, &@@shared_tests[test_name]
    end
  end
end

class BookTest < ActiveSupport::TestCase
  extend SharedTests

  shared_test_for "validate_presence" do |attr_name|
    assert_false Books.new(valid_attrs.merge(attr_name => nil)).valid?
  end

  shared_test "validate_presence", 'foo', :foo
  shared_test "validate_presence", 'bar', :bar
end

module SharedExamplesForAThing
  def test_a_thing_does_something
    ...
  end
end

class ThingTest < Test::Unit::TestCase
  include SharedExamplesForAThing
end