class RestTestHooks

class RestTestHooks {
    
    /**
     * Implements hook_entity_field_access().
     *
     * @see \Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase::setUp()
     */
    public function entityFieldAccess($operation, FieldDefinitionInterface $field_definition, AccountInterface $account, ?FieldItemListInterface $items = NULL) {
        // @see \Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase::testPost()
        // @see \Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase::testPatch()
        if ($field_definition->getName() === 'field_rest_test') {
            switch ($operation) {
                case 'view':
                    // Never ever allow this field to be viewed: this lets
                    // EntityResourceTestBase::testGet() test in a "vanilla" way.
                    return AccessResult::forbidden();
                case 'edit':
                    return AccessResult::forbidden();
            }
        }
        // @see \Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase::testGet()
        // @see \Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase::testPatch()
        if ($field_definition->getName() === 'field_rest_test_multivalue') {
            switch ($operation) {
                case 'view':
                    // Never ever allow this field to be viewed: this lets
                    // EntityResourceTestBase::testGet() test in a "vanilla" way.
                    return AccessResult::forbidden();
            }
        }
        // @see \Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase::testGet()
        // @see \Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase::testPatch()
        if ($field_definition->getName() === 'rest_test_validation') {
            switch ($operation) {
                case 'view':
                    // Never ever allow this field to be viewed: this lets
                    // EntityResourceTestBase::testGet() test in a "vanilla" way.
                    return AccessResult::forbidden();
            }
        }
        // No opinion.
        return AccessResult::neutral();
    }
    
    /**
     * Implements hook_entity_base_field_info().
     */
    public function entityBaseFieldInfo(EntityTypeInterface $entity_type) {
        $fields = [];
        $fields['rest_test_validation'] = BaseFieldDefinition::create('string')->setLabel(t('REST test validation field'))
            ->setDescription(t('A text field with some special validations attached used for testing purposes'))
            ->addConstraint('rest_test_validation');
        return $fields;
    }

}