diff --git a/core/modules/comment/src/Tests/CommentTranslationUITest.php b/core/modules/comment/src/Tests/CommentTranslationUITest.php
index 5e1e8a6..a0d13a9 100644
--- a/core/modules/comment/src/Tests/CommentTranslationUITest.php
+++ b/core/modules/comment/src/Tests/CommentTranslationUITest.php
@@ -118,11 +118,10 @@ protected function assertPublishedStatus() {
     $languages = $this->container->get('language_manager')->getLanguages();
 
     // Check that simple users cannot see unpublished field translations.
-    $path = $entity->url();
     foreach ($this->langcodes as $index => $langcode) {
       $translation = $this->getTranslation($entity, $langcode);
       $value = $this->getValue($translation, 'comment_body', $langcode);
-      $this->drupalGet($path, array('language' => $languages[$langcode]));
+      $this->drupalGet($entity->urlInfo(), array('language' => $languages[$langcode]));
       if ($index > 0) {
         $this->assertNoRaw($value, 'Unpublished field translation is not shown.');
       }
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationUITest.php b/core/modules/content_translation/src/Tests/ContentTranslationUITest.php
index a1a8eab..775df7a 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationUITest.php
+++ b/core/modules/content_translation/src/Tests/ContentTranslationUITest.php
@@ -10,6 +10,7 @@
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageInterface;
+use Drupal\Core\Url;
 use Drupal\language\Entity\ConfigurableLanguage;
 
 /**
@@ -53,9 +54,9 @@ protected function doTestBasicTranslation() {
     $this->entityId = $this->createEntity($values[$default_langcode], $default_langcode);
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
     $this->assertTrue($entity, 'Entity found in the database.');
-    $this->drupalGet($entity->url());
+    $this->drupalGet($entity->urlInfo());
     $this->assertResponse(200, 'Entity URL is valid.');
-    $this->drupalGet($entity->url('drupal:content-translation-overview'));
+    $this->drupalGet($entity->urlInfo('drupal:content-translation-overview'));
     $this->assertNoText('Source language', 'Source language column correctly hidden.');
 
     $translation = $this->getTranslation($entity, $default_langcode);
@@ -71,14 +72,17 @@ protected function doTestBasicTranslation() {
     $language = ConfigurableLanguage::load($langcode);
     $values[$langcode] = $this->getNewEntityValues($langcode);
 
-    $content_translation_path = $entity->url('drupal:content-translation-overview', array('language' => $language));
-    $path = $content_translation_path . '/add/' . $default_langcode . '/' . $langcode;
-    $this->drupalPostForm($path, $this->getEditValues($values, $langcode), $this->getFormSubmitActionForNewTranslation($entity, $langcode));
+    $add_url = Url::fromRoute('content_translation.translation_add_' . $entity->getEntityTypeId(), [
+      $entity->getEntityTypeId() => $entity->id(),
+      'source' => $default_langcode,
+      'target' => $langcode
+    ], array('language' => $language));
+    $this->drupalPostForm($add_url, $this->getEditValues($values, $langcode), $this->getFormSubmitActionForNewTranslation($entity, $langcode));
     if ($this->testLanguageSelector) {
       $this->assertNoFieldByXPath('//select[@id="edit-langcode-0-value"]', NULL, 'Language selector correctly disabled on translations.');
     }
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
-    $this->drupalGet($entity->url('drupal:content-translation-overview'));
+    $this->drupalGet($entity->urlInfo('drupal:content-translation-overview'));
     $this->assertNoText('Source language', 'Source language column correctly hidden.');
 
     // Switch the source language.
@@ -86,20 +90,27 @@ protected function doTestBasicTranslation() {
     $language = ConfigurableLanguage::load($langcode);
     $source_langcode = 'it';
     $edit = array('source_langcode[source]' => $source_langcode);
-    $content_translation_path = $entity->url('drupal:content-translation-overview', array('language' => $language));
-    $path = $content_translation_path . '/add/' . $default_langcode . '/' . $langcode;
+    $add_url = Url::fromRoute('content_translation.translation_add_' . $entity->getEntityTypeId(), [
+      $entity->getEntityTypeId() => $entity->id(),
+      'source' => $default_langcode,
+      'target' => $langcode
+    ], array('language' => $language));
     // This does not save anything, it merely reloads the form and fills in the
     // fields with the values from the different source language.
-    $this->drupalPostForm($path, $edit, t('Change'));
+    $this->drupalPostForm($add_url, $edit, t('Change'));
     $this->assertFieldByXPath("//input[@name=\"{$this->fieldName}[0][value]\"]", $values[$source_langcode][$this->fieldName][0]['value'], 'Source language correctly switched.');
 
     // Add another translation and mark the other ones as outdated.
     $values[$langcode] = $this->getNewEntityValues($langcode);
     $edit = $this->getEditValues($values, $langcode) + array('content_translation[retranslate]' => TRUE);
-    $path = $content_translation_path . '/add/' . $source_langcode . '/' . $langcode;
-    $this->drupalPostForm($path, $edit, $this->getFormSubmitActionForNewTranslation($entity, $langcode));
+    $add_url = Url::fromRoute('content_translation.translation_add_' . $entity->getEntityTypeId(), [
+      $entity->getEntityTypeId() => $entity->id(),
+      'source' => $source_langcode,
+      'target' => $langcode
+    ], array('language' => $language));
+    $this->drupalPostForm($add_url, $edit, $this->getFormSubmitActionForNewTranslation($entity, $langcode));
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
-    $this->drupalGet($entity->url('drupal:content-translation-overview'));
+    $this->drupalGet($entity->urlInfo('drupal:content-translation-overview'));
     $this->assertText('Source language', 'Source language column correctly shown.');
 
     // Check that the entered values have been correctly stored.
@@ -119,7 +130,7 @@ protected function doTestBasicTranslation() {
    */
   protected function doTestTranslationOverview() {
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
-    $this->drupalGet($entity->url('drupal:content-translation-overview'));
+    $this->drupalGet($entity->urlInfo('drupal:content-translation-overview'));
 
     foreach ($this->langcodes as $langcode) {
       if ($entity->hasTranslation($langcode)) {
@@ -144,15 +155,15 @@ protected function doTestOutdatedStatus() {
 
     // Mark translations as outdated.
     $edit = array('content_translation[retranslate]' => TRUE);
-    $edit_path = $entity->url('edit-form', array('language' => $languages[$langcode]));
+    $edit_path = $entity->urlInfo('edit-form', array('language' => $languages[$langcode]));
     $this->drupalPostForm($edit_path, $edit, $this->getFormSubmitAction($entity, $langcode));
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
 
     // Check that every translation has the correct "outdated" status, and that
     // the Translation fieldset is open if the translation is "outdated".
     foreach ($this->langcodes as $added_langcode) {
-      $path = $entity->url('edit-form', array('language' => ConfigurableLanguage::load($added_langcode)));
-      $this->drupalGet($path);
+      $url = $entity->urlInfo('edit-form', array('language' => ConfigurableLanguage::load($added_langcode)));
+      $this->drupalGet($url);
       if ($added_langcode == $langcode) {
         $this->assertFieldByXPath('//input[@name="content_translation[retranslate]"]', FALSE, 'The retranslate flag is not checked by default.');
         $this->assertFalse($this->xpath('//details[@id="edit-content-translation" and @open="open"]'), 'The translation tab should be collapsed by default.');
@@ -161,8 +172,8 @@ protected function doTestOutdatedStatus() {
         $this->assertFieldByXPath('//input[@name="content_translation[outdated]"]', TRUE, 'The translate flag is checked by default.');
         $this->assertTrue($this->xpath('//details[@id="edit-content-translation" and @open="open"]'), 'The translation tab is correctly expanded when the translation is outdated.');
         $edit = array('content_translation[outdated]' => FALSE);
-        $this->drupalPostForm($path, $edit, $this->getFormSubmitAction($entity, $added_langcode));
-        $this->drupalGet($path);
+        $this->drupalPostForm($url, $edit, $this->getFormSubmitAction($entity, $added_langcode));
+        $this->drupalGet($url);
         $this->assertFieldByXPath('//input[@name="content_translation[retranslate]"]', FALSE, 'The retranslate flag is now shown.');
         $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
         $this->assertFalse($entity->translation[$added_langcode]['outdated'], 'The "outdated" status has been correctly stored.');
@@ -179,16 +190,16 @@ protected function doTestPublishedStatus() {
     // Unpublish translations.
     foreach ($this->langcodes as $index => $langcode) {
       if ($index > 0) {
-        $path = $entity->url('edit-form', array('language' => ConfigurableLanguage::load($langcode)));
+        $url = $entity->urlInfo('edit-form', array('language' => ConfigurableLanguage::load($langcode)));
         $edit = array('content_translation[status]' => FALSE);
-        $this->drupalPostForm($path, $edit, $this->getFormSubmitAction($entity, $langcode));
+        $this->drupalPostForm($url, $edit, $this->getFormSubmitAction($entity, $langcode));
         $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
         $this->assertFalse($entity->translation[$langcode]['status'], 'The translation has been correctly unpublished.');
       }
     }
 
     // Check that the last published translation cannot be unpublished.
-    $this->drupalGet($entity->url('edit-form'));
+    $this->drupalGet($entity->urlInfo('edit-form'));
     $this->assertFieldByXPath('//input[@name="content_translation[status]" and @disabled="disabled"]', TRUE, 'The last translation is published and cannot be unpublished.');
   }
 
@@ -210,8 +221,8 @@ protected function doTestAuthoringInfo() {
         'content_translation[name]' => $user->getUsername(),
         'content_translation[created]' => format_date($values[$langcode]['created'], 'custom', 'Y-m-d H:i:s O'),
       );
-      $path = $entity->url('edit-form', array('language' => ConfigurableLanguage::load($langcode)));
-      $this->drupalPostForm($path, $edit, $this->getFormSubmitAction($entity, $langcode));
+      $url = $entity->urlInfo('edit-form', array('language' => ConfigurableLanguage::load($langcode)));
+      $this->drupalPostForm($url, $edit, $this->getFormSubmitAction($entity, $langcode));
     }
 
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
@@ -227,7 +238,7 @@ protected function doTestAuthoringInfo() {
       'content_translation[name]' => $this->randomMachineName(12),
       'content_translation[created]' => '19/11/1978',
     );
-    $this->drupalPostForm($path, $edit, $this->getFormSubmitAction($entity, $langcode));
+    $this->drupalPostForm($entity->urlInfo('edit-form'), $edit, $this->getFormSubmitAction($entity, $langcode));
     $this->assertTrue($this->xpath('//div[contains(@class, "error")]//ul'), 'Invalid values generate a list of form errors.');
     $this->assertEqual($entity->translation[$langcode]['uid'], $values[$langcode]['uid'], 'Translation author correctly kept.');
     $this->assertEqual($entity->translation[$langcode]['created'], $values[$langcode]['created'], 'Translation date correctly kept.');
@@ -240,8 +251,8 @@ protected function doTestTranslationDeletion() {
     // Confirm and delete a translation.
     $langcode = 'fr';
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
-    $path = $entity->url('edit-form', array('language' => ConfigurableLanguage::load($langcode)));
-    $this->drupalPostForm($path, array(), t('Delete translation'));
+    $url = $entity->urlInfo('edit-form', array('language' => ConfigurableLanguage::load($langcode)));
+    $this->drupalPostForm($url, array(), t('Delete translation'));
     $this->drupalPostForm(NULL, array(), t('Delete'));
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
     if ($this->assertTrue(is_object($entity), 'Entity found')) {
diff --git a/core/modules/node/src/Tests/NodeTranslationUITest.php b/core/modules/node/src/Tests/NodeTranslationUITest.php
index 01bd5e9..865c881 100644
--- a/core/modules/node/src/Tests/NodeTranslationUITest.php
+++ b/core/modules/node/src/Tests/NodeTranslationUITest.php
@@ -10,6 +10,7 @@
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\content_translation\Tests\ContentTranslationUITest;
 use Drupal\Core\Language\LanguageInterface;
+use Drupal\Core\Url;
 
 /**
  * Tests the Node Translation UI.
@@ -144,8 +145,8 @@ protected function doTestAuthoringInfo() {
         'promote[value]' => $values[$langcode]['promote'],
       );
       $options = array('language' => $languages[$langcode]);
-      $path = $entity->url('edit-form', $options);
-      $this->drupalPostForm($path, $edit, $this->getFormSubmitAction($entity, $langcode), $options);
+      $url = $entity->urlInfo('edit-form', $options);
+      $this->drupalPostForm($url, $edit, $this->getFormSubmitAction($entity, $langcode), $options);
     }
 
     $entity = entity_load($this->entityTypeId, $this->entityId, TRUE);
@@ -293,7 +294,7 @@ function testTranslationRendering() {
     $this->doTestTranslations('node/' . $node->id(), $values);
 
     // Test that the node page has the correct alternate hreflang links.
-    $this->doTestAlternateHreflangLinks('node/' . $node->id());
+    $this->doTestAlternateHreflangLinks($node->urlInfo());
   }
 
   /**
@@ -315,20 +316,23 @@ protected function doTestTranslations($path, array $values) {
   /**
    * Tests that the given path provides the correct alternate hreflang links.
    *
-   * @param string $path
+   * @param \Drupal\Core\Url $url
    *   The path to be tested.
    */
-  protected function doTestAlternateHreflangLinks($path) {
+  protected function doTestAlternateHreflangLinks(Url $url) {
     $languages = $this->container->get('language_manager')->getLanguages();
+    $url->setOption('absolute', TRUE);
+    $urls = [];
     foreach ($this->langcodes as $langcode) {
-      $urls[$langcode] = _url($path, array('absolute' => TRUE, 'language' => $languages[$langcode]));
+      $language_url = clone $url;
+      $urls[$langcode] = $language_url->setOption('language', $languages[$langcode]);
     }
     foreach ($this->langcodes as $langcode) {
-      $this->drupalGet($path, array('language' => $languages[$langcode]));
-      foreach ($urls as $alternate_langcode => $url) {
+      $this->drupalGet($urls[$langcode]);
+      foreach ($urls as $alternate_langcode => $language_url) {
         // Retrieve desired link elements from the HTML head.
         $links = $this->xpath('head/link[@rel = "alternate" and @href = :href and @hreflang = :hreflang]',
-          array(':href' => $url, ':hreflang' => $alternate_langcode));
+          array(':href' => $language_url->toString(), ':hreflang' => $alternate_langcode));
         $this->assert(isset($links[0]), format_string('The %langcode node translation has the correct alternate hreflang link for %alternate_langcode: %link.', array('%langcode' => $langcode, '%alternate_langcode' => $alternate_langcode, '%link' => $url)));
       }
     }
diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index 47eb889..812995a 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -27,6 +27,7 @@
 use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\Core\Datetime\DrupalDateTime;
 use Drupal\block\Entity\Block;
+use Drupal\Core\Url;
 use Symfony\Component\HttpFoundation\Request;
 use Drupal\user\Entity\Role;
 
@@ -1474,9 +1475,13 @@ protected function isInChildSite() {
    *   The retrieved HTML string, also available as $this->getRawContent()
    */
   protected function drupalGet($path, array $options = array(), array $headers = array()) {
+    if ($path instanceof Url) {
+      $url = $path->setOption('absolute', TRUE)->toString();
+    }
     // Assume that paths that start with a / are already fully generated
     // URL's that are just missing $base_root.
-    if (isset($path[0]) && $path[0] == '/') {
+    elseif (isset($path[0]) && $path[0] == '/') {
+      throw new \Exception($path);
       $url = $GLOBALS['base_root'] . $path;
     }
     // The URL generator service is not necessarily available yet; e.g., in