workbench_email-8.x-1.x-dev/tests/modules/workbench_email_test/workbench_email_test.module

<?php

/**
 * @file
 * Contains main module functions.
 */

use Drupal\Core\Access\AccessResult;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Session\AccountInterface;

/**
 * Implements hook_ENTITY_TYPE_access().
 */
function workbench_email_test_node_access(EntityInterface $entity, $operation, AccountInterface $account) {
  if ($account->getEmail() === 'editor2@example.com' && $operation === 'update') {
    return AccessResult::forbidden();
  }
  return AccessResult::neutral();
}

/**
 * Implements hook_mail_alter().
 */
function workbench_email_test_mail_alter(&$message) {
  $nid = $message['params']['entity']->id();

  // Add the node id to the subject so we can test the entity is available
  // as a message param.
  $message['subject'] .= " (node id: {$nid})";
}