diff -u b/core/modules/language/src/Tests/LanguageNegotiationContentEntityTest.php b/core/modules/language/src/Tests/LanguageNegotiationContentEntityTest.php
--- b/core/modules/language/src/Tests/LanguageNegotiationContentEntityTest.php
+++ b/core/modules/language/src/Tests/LanguageNegotiationContentEntityTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\language\Tests;
 
+use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\entity_test\Entity\EntityTest;
 use Drupal\language\Entity\ConfigurableLanguage;
@@ -59,28 +60,25 @@
    */
   public function testDefaultConfiguration() {
     $translation = $this->entity;
-    $url = $translation->urlInfo()->toString();
-    $this->drupalGet($url);
+    $this->drupalGet($translation->urlInfo());
     $last = $this->container->get('state')->get('language_test.language_negotiation_last');
     $last_content_language = $last[LanguageInterface::TYPE_CONTENT];
     $last_interface_language = $last[LanguageInterface::TYPE_INTERFACE];
-    $this->assertTrue(($last_interface_language == $last_content_language) && ($last_content_language == $translation->language()->getId()), 'Interface language and Content language are the same as the translation language of the entity.');
+    $this->assertTrue(($last_interface_language == $last_content_language) && ($last_content_language == $translation->language()->getId()), new FormattableMarkup('Interface language %interface_language and Content language %content_language are the same as the translation language %translation_language of the entity.', ['%interface_language' => $last_interface_language, '%content_language' => $last_content_language, '%translation_language' => $translation->language()->getId()]));
 
     $translation = $this->entity->getTranslation('es');
-    $url = $translation->urlInfo()->toString();
-    $this->drupalGet($url);
+    $this->drupalGet($translation->urlInfo());
     $last = $this->container->get('state')->get('language_test.language_negotiation_last');
     $last_content_language = $last[LanguageInterface::TYPE_CONTENT];
     $last_interface_language = $last[LanguageInterface::TYPE_INTERFACE];
-    $this->assertTrue(($last_interface_language == $last_content_language) && ($last_content_language == $translation->language()->getId()), 'Interface language and Content language are the same as the translation language of the entity.');
+    $this->assertTrue(($last_interface_language == $last_content_language) && ($last_content_language == $translation->language()->getId()), new FormattableMarkup('Interface language %interface_language and Content language %content_language are the same as the translation language %translation_language of the entity.', ['%interface_language' => $last_interface_language, '%content_language' => $last_content_language, '%translation_language' => $translation->language()->getId()]));
 
     $translation = $this->entity->getTranslation('fr');
-    $url = $translation->urlInfo()->toString();
-    $this->drupalGet($url);
+    $this->drupalGet($translation->urlInfo());
     $last = $this->container->get('state')->get('language_test.language_negotiation_last');
     $last_content_language = $last[LanguageInterface::TYPE_CONTENT];
     $last_interface_language = $last[LanguageInterface::TYPE_INTERFACE];
-    $this->assertTrue(($last_interface_language == $last_content_language) && ($last_content_language == $translation->language()->getId()), 'Interface language and Content language are the same as the translation language of the entity.');
+    $this->assertTrue(($last_interface_language == $last_content_language) && ($last_content_language == $translation->language()->getId()), new FormattableMarkup('Interface language %interface_language and Content language %content_language are the same as the translation language %translation_language of the entity.', ['%interface_language' => $last_interface_language, '%content_language' => $last_content_language, '%translation_language' => $translation->language()->getId()]));
   }
 
   /**