def quick_gem(name, version='2')
    require 'rubygems/specification'

    spec = Gem::Specification.new do |s|
      s.platform    = Gem::Platform::RUBY
      s.name        = name
      s.version     = version
      s.author      = 'A User'
      s.email       = 'example@example.com'
      s.homepage    = 'http://example.com'
      s.summary     = "this is a summary"
      s.description = "This is a test description"

      yield(s) if block_given?
    end

    Gem::Specification.map # HACK: force specs to (re-)load before we write

    written_path = write_file spec.spec_file do |io|
      io.write spec.to_ruby_for_cache
    end

    spec.loaded_from = spec.loaded_from = written_path

    Gem::Specification.add_spec spec.for_cache

    return spec
  end
#
Creates a Gem::Specification with a minimum of extra work.  +name+ and
+version+ are the gem's name and version,  platform, author, email,
homepage, summary and description are defaulted.  The specification is
yielded for customization.

The gem is added to the installed gems in +@gemhome+ and to the current
source_index.

Use this with #write_file to build an installed gem.