diff --git a/lib/tests/behat/behat_data_generators.php b/lib/tests/behat/behat_data_generators.php
index d5b00d6a411..26ff26fbffb 100644
--- a/lib/tests/behat/behat_data_generators.php
+++ b/lib/tests/behat/behat_data_generators.php
@@ -727,6 +727,11 @@ class behat_data_generators extends behat_base {
     protected function get_grouping_id($idnumber) {
         global $DB;
 
+        // Do not fetch grouping ID for empty grouping idnumber.
+        if (empty($idnumber)) {
+            return null;
+        }
+
         if (!$id = $DB->get_field('groupings', 'id', array('idnumber' => $idnumber))) {
             throw new Exception('The specified grouping with idnumber "' . $idnumber . '" does not exist');
         }