diff -u b/core/modules/filter/src/Tests/FilterUnitTest.php b/core/modules/filter/src/Tests/FilterUnitTest.php
--- b/core/modules/filter/src/Tests/FilterUnitTest.php
+++ b/core/modules/filter/src/Tests/FilterUnitTest.php
@@ -9,7 +9,7 @@
 
 use Drupal\Component\Utility\Html;
 use Drupal\Component\Utility\String;
-use Drupal\Component\Utility\Xss;
+use Drupal\Component\Utility\xss;
 use Drupal\filter\FilterPluginCollection;
 use Drupal\simpletest\KernelTestBase;
 
@@ -201,8 +201,8 @@
     };
     // Editor XSS filter.
     $test_editor_xss_filter = function ($input) {
-      $blacklisted_tags = array('script', 'style', 'link', 'embed', 'object');
-      return Xss::filter($input);
+      $allowed_tags = array('img');
+      return Xss::filter($input, $allowed_tags);
     };
 
     // All the tricky cases encountered at https://drupal.org/node/2105841.