diff -u b/src/Tests/DiffViewsTest.php b/src/Tests/DiffViewsTest.php
--- b/src/Tests/DiffViewsTest.php
+++ b/src/Tests/DiffViewsTest.php
@@ -71,7 +71,7 @@
       // Additional route options
       [
         'query' => [
-          'destination' => '/node/1/diff-views',
+          'destination' => Url::fromUri('internal:/node/1/diff-views')->toString(),
         ],
       ]
     );