BundleTestBundle.php

<?php

/**
 * @file
 * Definition of Drupal\bundle_test\BundleTestBundle.
 */
namespace Drupal\bundle_test;

use Symfony\Component\DependencyInjection\Definition;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Reference;
use Symfony\Component\HttpKernel\Bundle\Bundle;

/**
 * Test bundle class.
 */
class BundleTestBundle extends Bundle {
  public function build(ContainerBuilder $container) {
    $container
      ->register('bundle_test_class', 'Drupal\\bundle_test\\TestClass')
      ->addTag('event_subscriber');

    // Override a default bundle used by core to a dummy class.
    $container
      ->register('file.usage', 'Drupal\\bundle_test\\TestFileUsage');
  }

}