public function test_customize_loaded_components_filter() {
    $manager = new WP_Customize_Manager();
    $this->assertInstanceOf( 'WP_Customize_Widgets', $manager->widgets );
    $this->assertInstanceOf( 'WP_Customize_Nav_Menus', $manager->nav_menus );

    add_filter( 'customize_loaded_components', array( $this, 'return_array_containing_widgets' ), 10, 2 );
    $manager = new WP_Customize_Manager();
    $this->assertInstanceOf( 'WP_Customize_Widgets', $manager->widgets );
    $this->assertEmpty( $manager->nav_menus );
    remove_all_filters( 'customize_loaded_components' );

    add_filter( 'customize_loaded_components', array( $this, 'return_array_containing_nav_menus' ), 10, 2 );
    $manager = new WP_Customize_Manager();
    $this->assertInstanceOf( 'WP_Customize_Nav_Menus', $manager->nav_menus );
    $this->assertEmpty( $manager->widgets );
    remove_all_filters( 'customize_loaded_components' );

    add_filter( 'customize_loaded_components', '__return_empty_array' )  <;
    $manager = new WP_Customize_Manager();
    $this->assertEmpty( $manager->widgets );
    $this->assertEmpty( $manager->nav_menus );
    remove_all_filters( 'customize_loaded_components' );
  }