using

superclass.rb

require 'test/unit'

module Kernel
  def using(resource)
    begin
      yield if block_given?
    ensure
      resource.dispose
    end
  end
end

class TestUsing < Test::Unit::TestCase
  class Resource
    def dispose
      @disposed = true
    end

    def disposed?
      @disposed
    end
  end

  def test_disposes_of_resource
    r = Resource.new
    using(r) {}
    assert r.disposed?
  end

  def test_disposes_of_resource_in_case_of_exception
    r = Resource.new
    assert_raises(Exception) do
      using(r) { raise Exception }
    end
    assert r.disposed?
  end

end