diff --git a/core/modules/system/tests/src/Functional/Ajax/OffCanvasDialogTest.php b/core/modules/system/tests/src/Functional/Ajax/OffCanvasDialogTest.php
index aa4edaa924..c2c4c6dc93 100644
--- a/core/modules/system/tests/src/Functional/Ajax/OffCanvasDialogTest.php
+++ b/core/modules/system/tests/src/Functional/Ajax/OffCanvasDialogTest.php
@@ -45,6 +45,7 @@ public function testDialog() {
           'resizable' => 'w',
           'draggable' => FALSE,
           'drupalAutoButtons' => FALSE,
+          'drupalOffCanvasPosition' => 'side',
           'buttons' => [],
           'dialogClass' => 'ui-dialog-off-canvas ui-dialog-position-side',
           'width' => 300,
diff --git a/core/tests/Drupal/Tests/Core/Ajax/OpenOffCanvasDialogCommandTest.php b/core/tests/Drupal/Tests/Core/Ajax/OpenOffCanvasDialogCommandTest.php
index c68368a4f4..5cfdb64fc9 100644
--- a/core/tests/Drupal/Tests/Core/Ajax/OpenOffCanvasDialogCommandTest.php
+++ b/core/tests/Drupal/Tests/Core/Ajax/OpenOffCanvasDialogCommandTest.php
@@ -33,6 +33,7 @@ public function testRender() {
         'buttons' => [],
         'dialogClass' => 'ui-dialog-off-canvas ui-dialog-position-side',
         'width' => 300,
+        'drupalOffCanvasPosition' => 'side',
       ],
       'effect' => 'fade',
       'speed' => 1000,