User not deleted cleanly

My custom module happens to create some data based on a new user being created and expects to be given a chance to remove that data via hook_user(). However, it appears that the simpletest module does not ever call the hook_user() when removing a user.

simpletest.module delete code:

    while (sizeof($this->_cleanupUsers) > 0) {
      $uid = array_pop($this->_cleanupUsers);
      db_query('DELETE FROM {users} WHERE uid = %d',       $uid);
      db_query('DELETE FROM {users_roles} WHERE uid = %d', $uid);
      db_query('DELETE FROM {authmap} WHERE uid = %d',     $uid);
    }

As compared to user.module user delete code:

  if (arg(2) == 'delete') {
    if ($edit['confirm']) {
      db_query('DELETE FROM {users} WHERE uid = %d', $account->uid);
      db_query('DELETE FROM {sessions} WHERE uid = %d', $account->uid);
      db_query('DELETE FROM {users_roles} WHERE uid = %d', $account->uid);
      db_query('DELETE FROM {authmap} WHERE uid = %d', $account->uid);
      watchdog('user', t('Deleted user: %name %email.', array('%name' => theme('placeholder', $account->name), '%email' => theme('placeholder', '<'. $account->mail .'>'))), WATCHDOG_NOTICE);
      drupal_set_message(t('The account has been deleted.'));
      module_invoke_all('user', 'delete', $edit, $account);
      drupal_goto('admin/user');
    }

It would be great if the simpletest module could actually call user.module's code so that there is no duplication (and therefore potential for falling out of sync) of code. But, given the 'confirm' page, I'm not entirely sure what the best way to go about this would be.

I'm happy to help code a solution if others have good ideas about how best to go about it.

Cheers,
Justin