class Gem::TestCase

def self.rubybin
  ruby = ENV["RUBY"]
  return ruby if ruby
  ruby = "ruby"
  rubyexe = "#{ruby}.exe"
  3.times do
    if File.exist? ruby and File.executable? ruby and !File.directory? ruby
      return File.expand_path(ruby)
    end
    if File.exist? rubyexe and File.executable? rubyexe
      return File.expand_path(rubyexe)
    end
    ruby = File.join("..", ruby)
  end
  begin
    require "rbconfig"
    File.join(RbConfig::CONFIG["bindir"],
              RbConfig::CONFIG["ruby_install_name"] +
              RbConfig::CONFIG["EXEEXT"])
  rescue LoadError
    "ruby"
  end
end