installConfig('system'); $this->installConfig('language'); /** @var \Drupal\language\Config\LanguageConfigFactoryOverride $config_factory_override */ $config_factory_override = \Drupal::service('language.config_factory_override'); $this->assertEquals('en', $config_factory_override->getLanguage()->getId()); ConfigurableLanguage::createFromLangcode('de')->save(); // Invalidate the container. $this->config('system.site')->set('default_langcode', 'de')->save(); drupal_flush_all_caches(); $config_factory_override = \Drupal::service('language.config_factory_override'); $this->assertEquals('de', $config_factory_override->getLanguage()->getId()); } }