# File lib/bundler/runtime.rb, line 12
    def setup(*groups)
      # Has to happen first
      clean_load_path

      specs = groups.any? ? specs_for(groups) : requested_specs

      cripple_rubygems(specs)
      replace_rubygems_paths

      # Activate the specs
      specs.each do |spec|
        unless spec.loaded_from
          raise GemNotFound, "#{spec.full_name} is cached, but not installed."
        end

        Gem.loaded_specs[spec.name] = spec
        spec.load_paths.each do |path|
          $LOAD_PATH.unshift(path) unless $LOAD_PATH.include?(path)
        end
      end
      self
    end