NavigationTestBlock.php

<?php

declare (strict_types=1);
namespace Drupal\navigation_test_block\Plugin\Block;

use Drupal\Core\Block\Attribute\Block;
use Drupal\Core\Block\BlockBase;
use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\Url;

/**
 * Defines a dummy navigation block for testing purposes.
 *
 * @internal
 */
final class NavigationTestBlock extends BlockBase {
  
  /**
   * {@inheritdoc}
   */
  public function build() : array {
    $config = $this->configuration;
    $build = [];
    return $build + [
      '#title' => $config['label'],
      '#theme' => 'navigation_menu',
      '#menu_name' => 'test',
      '#items' => [
        [
          'title' => 'Test Navigation Block',
          'class' => 'test-block',
          'icon' => [
            'icon_id' => 'test-block',
          ],
          'url' => Url::fromRoute('<front>'),
        ],
      ],
    ];
  }

}