How to validate programmatically using a known constraint UniqueField

inAnyPartOrHookToUpdateOrSave.php

<?php
$data = [
  'type' => 'article',
  'title' => 'THis is an article test programmatically created',
  'field_email' => [
    'value' => '[email protected]'
  ]
];
$node = \Drupal::entityTypeManager()->getStorage('node')->create($data);
$violations = $node->validate();
// Validation failed.
if ($violations->count() > 0) {
    // Display an error message helping the user fix the problem.
    // These will be available indivudally in the $violations array
    // and can be accessed by $violations[0]->getMessage() for each violation.
    drupal_set_message($violations[0]->getMessage());
}
$node->save();


use Drupal\node\Entity\Node;

$node = Node::load(25);
$violations = $node->validate();
// Validation failed.
if ($violations->count() > 0) {
    // Display an error message helping the user fix the problem.
    // These will be available indivudally in the $violations array
    // and can be accessed by $violations[0]->getMessage() for each violation.
    drupal_set_message($violations[0]->getMessage());
}

mymodule.module.php

<?php
/**
 * Implements hook_entity_bundle_field_info_alter().
 */
function mymodule_entity_bundle_field_info_alter(&$fields, \Drupal\Core\Entity\EntityTypeInterface $entity_type, $bundle) {
  if ($entity_type->id() === 'node' && $bundle === 'article' && !empty($fields['field_email'])) {
    $fields['field_email']->addConstraint('UniqueField');
  }
}