rubybin

# File lib/rubygems/test_case.rb, line 1313
  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