Issue #3255250 by murilohp, daffie, longwave, Gábor Hojtsy: [Symfony 5]...

  /**

   * {@inheritdoc}

   *

   * @deprecated in drupal:9.4.0 and is removed from drupal:10.0.0. Use

   *   \Drupal\Core\Validation\DrupalTranslator::trans() instead.

   *

   * @see https://www.drupal.org/node/3255250

   */

  public function transChoice($id, $number, array $parameters = [], $domain = NULL, $locale = NULL) {

    @trigger_error(__NAMESPACE__ . '\DrupalTranslator::transChoice() is deprecated in drupal:9.4.0 and is removed from drupal:10.0.0. Use DrupalTranslator::trans() instead. See https://www.drupal.org/node/3255250', E_USER_DEPRECATED);

    // Violation messages can separated singular and plural versions by "|".

    $ids = explode('|', $id);

<?php

namespace Drupal\KernelTests\Core\Validation;

use Drupal\Core\DependencyInjection\ContainerBuilder;

use Drupal\Core\StringTranslation\PluralTranslatableMarkup;

use Drupal\Core\StringTranslation\TranslationManager;

use Drupal\Core\Validation\DrupalTranslator;

use Drupal\Tests\UnitTestCase;

/**

 * Tests the for translator.

 *

 * @coversDefaultClass \Drupal\Core\Validation\DrupalTranslator

 *

 * @group validation

 */

class DrupalTranslatorTest extends UnitTestCase {

  /**

   * {@inheritDoc}

   */

  public function setUp(): void {

    parent::setUp();

    // Set up a mock container as transChoice() will call for the

    // 'string_translation' service.

    $plural_translatable_markup = $this->getMockBuilder(PluralTranslatableMarkup::class)

      ->disableOriginalConstructor()

      ->getMock();

    $translation_manager = $this->getMockBuilder(TranslationManager::class)

      ->onlyMethods(['formatPlural'])

      ->disableOriginalConstructor()

      ->getMock();

    $translation_manager->expects($this->any())

      ->method('formatPlural')

      ->willReturn($plural_translatable_markup);

    $container = new ContainerBuilder();

    $container->set('string_translation', $translation_manager);

    \Drupal::setContainer($container);

  }

  /**

   * Test transChoice deprecation message.

   *

   * @covers ::transChoice

   * @group legacy

   */

  public function testDeprecation() {

    $this->expectDeprecation('Drupal\Core\Validation\DrupalTranslator::transChoice() is deprecated in drupal:9.4.0 and is removed from drupal:10.0.0. Use DrupalTranslator::trans() instead. See https://www.drupal.org/node/3255250');

    $translator = new DrupalTranslator();

    $this->assertInstanceOf(

      PluralTranslatableMarkup::class,

      $translator->transChoice('There is one apple | There are @count apples', 1)

    );

  }

}