Issue #2891754 by alexpott, samuel.mortenson, Joseph Zhao, Xano, Berdir,...

   */

  public function validate($items, Constraint $constraint) {

    /** @var \Drupal\Core\Field\FieldItemListInterface $items */

    /** @var \Drupal\user\UserInterface $account */

    /* @var \Drupal\user\UserInterface $account */

    $account = $items->getEntity();

    if (!isset($account)) {

      return;

    }

    $existing_value = NULL;

    if ($account->id()) {

      $account_unchanged = \Drupal::entityManager()

    // Only validate for existing user.

    if (!$account->isNew()) {

      $account_unchanged = \Drupal::entityTypeManager()

        ->getStorage('user')

        ->loadUnchanged($account->id());

      $existing_value = $account_unchanged->getEmail();

<?php

namespace Drupal\Tests\user\Unit\Plugin\Validation\Constraint;

use Drupal\Core\DependencyInjection\ContainerBuilder;

use Drupal\Core\Entity\EntityTypeManagerInterface;

use Drupal\Core\Field\FieldDefinitionInterface;

use Drupal\Core\Field\FieldItemListInterface;

use Drupal\Core\Session\AccountInterface;

use Drupal\Tests\UnitTestCase;

use Drupal\user\Plugin\Validation\Constraint\UserMailRequired;

use Drupal\user\Plugin\Validation\Constraint\UserMailRequiredValidator;

use Drupal\user\UserInterface;

use Drupal\user\UserStorageInterface;

use Symfony\Component\Validator\Context\ExecutionContextInterface;

/**

 * @coversDefaultClass \Drupal\user\Plugin\Validation\Constraint\UserMailRequiredValidator

 * @group user

 */

class UserMailRequiredValidatorTest extends UnitTestCase {

  /**

   * Creates a validator instance.

   *

   * @param bool $is_admin

   *   Whether or not the current user is an administrator.

   *

   * @return \Drupal\user\Plugin\Validation\Constraint\UserMailRequiredValidator

   *   The validator instance.

   */

  protected function createValidator($is_admin) {

    // Setup mocks that don't need to change.

    $unchanged_account = $this->prophesize(UserInterface::class);

    $unchanged_account->getEmail()->willReturn(NULL);

    $user_storage = $this->prophesize(UserStorageInterface::class);

    $user_storage->loadUnchanged(3)->willReturn($unchanged_account->reveal());

    $entity_type_manager = $this->prophesize(EntityTypeManagerInterface::class);

    $entity_type_manager->getStorage('user')->willReturn($user_storage->reveal());

    $current_user = $this->prophesize(AccountInterface::class);

    $current_user->id()->willReturn(3);

    $current_user->hasPermission("administer users")->willReturn($is_admin);

    $container = new ContainerBuilder();

    $container->set('entity_type.manager', $entity_type_manager->reveal());

    $container->set('current_user', $current_user->reveal());

    \Drupal::setContainer($container);

    return new UserMailRequiredValidator();

  }

  /**

   * @covers ::validate

   *

   * @dataProvider providerTestValidate

   */

  public function testValidate($items, $expected_violation, $is_admin = FALSE) {

    $constraint = new UserMailRequired();

    // If a violation is expected, then the context's addViolation method will

    // be called, otherwise it should not be called.

    $context = $this->prophesize(ExecutionContextInterface::class);

    if ($expected_violation) {

      $context->addViolation('@name field is required.', ['@name' => 'Email'])->shouldBeCalledTimes(1);

    }

    else {

      $context->addViolation()->shouldNotBeCalled();

    }

    $validator = $this->createValidator($is_admin);

    $validator->initialize($context->reveal());

    $validator->validate($items, $constraint);

  }

  /**

   * Data provider for ::testValidate().

   */

  public function providerTestValidate() {

    $cases = [];

    // Case 1: Empty user should be ignored.

    $items = $this->prophesize(FieldItemListInterface::class);

    $items->getEntity()->willReturn(NULL)->shouldBeCalledTimes(1);

    $cases['Empty user should be ignored'] = [$items->reveal(), FALSE];

    // Case 2: New users without an email should add a violation.

    $items = $this->prophesize(FieldItemListInterface::class);

    $account = $this->prophesize(UserInterface::class);

    $account->isNew()->willReturn(TRUE);

    $account->id()->shouldNotBeCalled();

    $field_definition = $this->prophesize(FieldDefinitionInterface::class);

    $field_definition->getLabel()->willReturn('Email');

    $account->getFieldDefinition("mail")->willReturn($field_definition->reveal())->shouldBeCalledTimes(1);

    $items->getEntity()->willReturn($account->reveal())->shouldBeCalledTimes(1);

    $items->isEmpty()->willReturn(TRUE);

    $cases['New users without an email should add a violation'] = [$items->reveal(), TRUE];

    // Case 3: Existing users without an email should add a violation.

    $items = $this->prophesize(FieldItemListInterface::class);

    $account = $this->prophesize(UserInterface::class);

    $account->isNew()->willReturn(FALSE);

    $account->id()->willReturn(3);

    $field_definition = $this->prophesize(FieldDefinitionInterface::class);

    $field_definition->getLabel()->willReturn('Email');

    $account->getFieldDefinition("mail")->willReturn($field_definition->reveal())->shouldBeCalledTimes(1);

    $items->getEntity()->willReturn($account->reveal())->shouldBeCalledTimes(1);

    $items->isEmpty()->willReturn(TRUE);

    $cases['Existing users without an email should add a violation'] = [$items->reveal(), TRUE];

    // Case 4: New user with an e-mail is valid.

    $items = $this->prophesize(FieldItemListInterface::class);

    $account = $this->prophesize(UserInterface::class);

    $account->isNew()->willReturn(TRUE);

    $account->id()->shouldNotBeCalled();

    $field_definition = $this->prophesize(FieldDefinitionInterface::class);

    $field_definition->getLabel()->willReturn('Email');

    $account->getFieldDefinition("mail")->willReturn($field_definition->reveal())->shouldBeCalledTimes(1);

    $items->getEntity()->willReturn($account->reveal())->shouldBeCalledTimes(1);

    $items->isEmpty()->willReturn(FALSE);

    $cases['New user with an e-mail is valid'] = [$items->reveal(), FALSE];

    // Case 5: Existing users with an email should be ignored.

    $items = $this->prophesize(FieldItemListInterface::class);

    $account = $this->prophesize(UserInterface::class);

    $account->isNew()->willReturn(FALSE);

    $account->id()->willReturn(3);

    $field_definition = $this->prophesize(FieldDefinitionInterface::class);

    $field_definition->getLabel()->willReturn('Email');

    $account->getFieldDefinition("mail")->willReturn($field_definition->reveal())->shouldBeCalledTimes(1);

    $items->getEntity()->willReturn($account->reveal())->shouldBeCalledTimes(1);

    $items->isEmpty()->willReturn(FALSE);

    $cases['Existing users with an email should be ignored'] = [$items->reveal(), FALSE];

    // Case 6: Existing users without an email should be ignored if the current

    // user is an administrator.

    $items = $this->prophesize(FieldItemListInterface::class);

    $account = $this->prophesize(UserInterface::class);

    $account->isNew()->willReturn(FALSE);

    $account->id()->willReturn(3);

    $field_definition = $this->prophesize(FieldDefinitionInterface::class);

    $field_definition->getLabel()->willReturn('Email');

    $account->getFieldDefinition("mail")->willReturn($field_definition->reveal())->shouldBeCalledTimes(1);

    $items->getEntity()->willReturn($account->reveal())->shouldBeCalledTimes(1);

    $items->isEmpty()->willReturn(TRUE);

    $cases['Existing users without an email should be ignored if the current user is an administrator.'] = [$items->reveal(), FALSE, TRUE];

    return $cases;

  }

}