diff --git a/resources/testdriver-vendor.js b/resources/testdriver-vendor.js
index e69de29bb2..2aa6805ec5 100644
--- a/resources/testdriver-vendor.js
+++ b/resources/testdriver-vendor.js
@@ -0,0 +1,3 @@
+window.test_driver.delete_all_cookies = async function() {
+	window.webdriver.deleteAllCookies();
+}