testEntityUrlLanguage example

    // language-url.     $config = $this->config('language.types');
    $config->set('configurable', [LanguageInterface::TYPE_INTERFACE, LanguageInterface::TYPE_CONTENT]);
    $config->set('negotiation.language_content.enabled', [
      LanguageNegotiationContentEntity::METHOD_ID => 0,
      LanguageNegotiationUrl::METHOD_ID => 1,
    ]);
    $config->save();

    // Without being on a content entity route the default entity URL tests     // should still pass.     $this->testEntityUrlLanguage();

    // Now switching to an entity route, so that the URL links are generated     // while being on an entity route.     $this->setCurrentRequestForRoute('/entity_test/{entity_test}', 'entity.entity_test.canonical');

    // The method language-content-entity should run before language-url and     // append query parameter for the content language and prevent language-url     // from overwriting the URL.     $this->assertStringContainsString('/en/entity_test/' . $this->entity->id() . '?' . LanguageNegotiationContentEntity::QUERY_PARAMETER . '=en', $this->entity->toUrl('canonical')->toString());
    $this->assertStringContainsString('/en/entity_test/' . $this->entity->id() . '?' . LanguageNegotiationContentEntity::QUERY_PARAMETER . '=es', $this->entity->getTranslation('es')->toUrl('canonical')->toString());
    $this->assertStringContainsString('/en/entity_test/' . $this->entity->id() . '?' . LanguageNegotiationContentEntity::QUERY_PARAMETER . '=fr', $this->entity->getTranslation('fr')->toUrl('canonical')->toString());