ConstraintsTest.php

<?php

namespace Drupal\KernelTests\Core\Validation;

use Drupal\KernelTests\KernelTestBase;

/**
 * Tests various low level constrains provided by core.
 *
 * @group Validation
 */
class ConstraintsTest extends KernelTestBase {
    
    /**
     * {@inheritdoc}
     */
    protected static $modules = [
        'config_test',
    ];
    
    /**
     * {@inheritdoc}
     */
    protected function setUp() : void {
        parent::setUp();
        $this->installConfig('config_test');
    }
    
    /**
     * @see \Drupal\Core\Validation\Plugin\Validation\Constraint\UuidConstraint
     */
    public function testUuid() {
        $typed_config_manager = \Drupal::service('config.typed');
        
        /** @var \Drupal\Core\Config\Schema\TypedConfigInterface $typed_config */
        $typed_config = $typed_config_manager->get('config_test.validation');
        $typed_config->get('uuid')
            ->setValue(\Drupal::service('uuid')->generate());
        $this->assertCount(0, $typed_config->validate());
        $typed_config->get('uuid')
            ->setValue(\Drupal::service('uuid')->generate() . '-invalid');
        $this->assertCount(1, $typed_config->validate());
    }

}