# File lib/bundler/runtime.rb, line 7
    def setup(*groups)
      groups.map! { |g| g.to_sym }

      # Has to happen first
      clean_load_path

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

      setup_environment
      Bundler.rubygems.replace_entrypoints(specs)

      # Activate the specs
      specs.each do |spec|
        unless spec.loaded_from
          raise GemNotFound, "#{spec.full_name} is missing. Run `bundle` to get it."
        end

        if activated_spec = Bundler.rubygems.loaded_specs(spec.name) and activated_spec.version != spec.version
          e = Gem::LoadError.new "You have already activated #{activated_spec.name} #{activated_spec.version}, " \
                                 "but your Gemfile requires #{spec.name} #{spec.version}. Prepending " \
                                 "`bundle exec` to your command may solve this."
          e.name = spec.name
          if e.respond_to?(:requirement=)
            e.requirement = Gem::Requirement.new(spec.version.to_s)
          else
            e.version_requirement = Gem::Requirement.new(spec.version.to_s)
          end
          raise e
        end

        Bundler.rubygems.mark_loaded(spec)
        load_paths = spec.load_paths.reject {|path| $LOAD_PATH.include?(path)}
        $LOAD_PATH.unshift(*load_paths)
      end

      setup_manpath

      lock

      self
    end