addCustomMenuCRUD example

  public function testMenuAdministration() {
    // Log in the user.     $this->drupalLogin($this->adminUser);
    $this->items = [];

    $this->menu = $this->addCustomMenu();
    $this->doMenuTests();
    $this->doTestMenuBlock();
    $this->addInvalidMenuLink();
    $this->addCustomMenuCRUD();

    // Verify that the menu links rebuild is idempotent and leaves the same     // number of links in the table.     /** @var \Drupal\Core\Menu\MenuLinkManagerInterface $menu_link_manager */
    $menu_link_manager = \Drupal::service('plugin.manager.menu.link');
    $before_count = $menu_link_manager->countMenuLinks(NULL);
    $menu_link_manager->rebuild();
    $after_count = $menu_link_manager->countMenuLinks(NULL);
    $this->assertSame($before_count, $after_count, 'MenuLinkManager::rebuild() does not add more links');
    // Do standard user tests.     // Log in the user.