public function test_construct_empty_menus() {
    do_action( 'customize_register', $this->wp_customize );
    $_wp_customize = $this->wp_customize;
    unset( $_wp_customize->nav_menus );

    $exception = null;
    try {
      $bad_setting = new WP_Customize_Nav_Menu_Setting( $_wp_customize, 'nav_menu_item[123]' );
      unset( $bad_setting );
    } catch ( Exception $e ) {
      $exception = $e;
    }
    $this->assertInstanceOf( 'Exception', $exception );
  }