trait FileSystemModuleDiscoveryDataProviderTrait in Drupal 9

trait FileSystemModuleDiscoveryDataProviderTrait {

  /**
   * A data provider that lists every module in core.
   *
   * @return array
   *   An array of module names to test.
   */
  public function coreModuleListDataProvider() {
    $prefix = dirname(__DIR__, 3) . DIRECTORY_SEPARATOR . 'modules';
    $module_dirs = array_keys(iterator_to_array(new \FilesystemIterator($prefix)));
    $module_names = array_map(function ($path) use ($prefix) {
      return str_replace($prefix . DIRECTORY_SEPARATOR, '', $path);
    }, $module_dirs);
    $modules_keyed = array_combine($module_names, $module_names);
    $data = array_map(function ($module) {
      return [
        $module,
      ];
    }, $modules_keyed);
    return $data;
  }

}