rubygems_bin_path.rb

  def self.bin_path(name, exec_name = nil, *requirements)
    # TODO: fails test_self_bin_path_bin_file_gone_in_latest
    # Gem::Specification.find_by_name(name, *requirements).bin_file exec_name

    raise ArgumentError, "you must supply exec_name" unless exec_name

    requirements = Gem::Requirement.default if
      requirements.empty?

    find_spec_for_exe(name, exec_name, requirements).bin_file exec_name
  end

  def self.find_spec_for_exe name, exec_name, requirements
    dep = Gem::Dependency.new name, requirements

    loaded = Gem.loaded_specs[name]

    return loaded if loaded && dep.matches_spec?(loaded)