function _simpletest_batch_operation($tests_init, $reporter_init, &$context) {
  // Ensure that all classes are loaded before we unserialize some instances.
  simpletest_get_total_test();
  
  if (!isset($context['sandbox']['max'])) {
    $context['sandbox']['max'] = $tests->getSize();
    $tests = unserialize($tests_init);
    $reporter = unserialize($reporter_init);
  }
  else {
    $tests = unserialize($context['sandbox']['tests']);
    $reporter = unserialize($context['results']);
  }

  $test_ran = $tests->runOneByOne($reporter);
  $size = $tests->getSize();
  
  $context['message'] = t('Processed test %test (remaining: @count of @max). !passes passes, !fails fails, !exceptions exceptions.', array('%test' => $test_ran, '@count' => $size, '@max' => $context['sandbox']['max'], '!passes' => $reporter->_passes, '!fails' => $reporter->_fails, '!exceptions' => $reporter->_exceptions));

  // Put back the tests and reporter.
  $context['sandbox']['tests'] = serialize($tests);
  $context['results'] = serialize($reporter);

  // Multistep processing: report progress.
  if ($size) {
    $context['finished'] = 1 - $size / $context['sandbox']['max'];
  }
}

function _simpletest_batch_finished($success, $results, $operations) {
  $_SESSION['simpletest_reporter'] = $results;
  if ($success) {
    drupal_set_message(t('The tests have finished running.'));
  }
  else {
    drupal_set_message(t('The tests did not successfully finish.'), 'error');
  }
}