MDL-68680 core_grades: check grade item before trigger delete event

lib/grade/grade_grade.php

@@ -252,6 +252,10 @@ public function load_grade_item() {
             $this->grade_item = grade_item::fetch(array('id'=>$this->itemid));
         }
 
+        if (empty($this->grade_item)) {
+            debugging("Missing grade item id $this->itemid", DEBUG_DEVELOPER);
+        }
+
         return $this->grade_item;
     }
 
@@ -1117,8 +1121,7 @@ public function delete($source = null) {
         $success = parent::delete($source);
 
         // If the grade was deleted successfully trigger a grade_deleted event.
-        if ($success) {
-            $this->load_grade_item();
+        if ($success && !empty($this->grade_item)) {
             \core\event\grade_deleted::create_from_grade($this)->trigger();
         }
 
@@ -1157,8 +1160,10 @@ protected function notify_changed($deleted) {
             return;
         }
 
-        // Load information about grade item
-        $this->load_grade_item();
+        // Load information about grade item, exit if the grade item is missing.
+        if (!$this->load_grade_item()) {
+            return;
+        }
 
         // Only course-modules have completion data
         if ($this->grade_item->itemtype!='mod') {

lib/grade/tests/grade_grade_test.php

@@ -40,6 +40,7 @@ public function test_grade_grade() {
         $this->sub_test_grade_grade_set_hidden();
         $this->sub_test_grade_grade_is_hidden();
         $this->sub_test_grade_grade_deleted();
+        $this->sub_test_grade_grade_deleted_event();
     }
 
     protected function sub_test_grade_grade_construct() {
@@ -506,4 +507,67 @@ private function add_feedback_file_to_copy() {
         $fs = get_file_storage();
         $fs->create_file_from_string($dummy, '');
     }
+
+    /**
+     * Tests grade_deleted event.
+     */
+    public function sub_test_grade_grade_deleted_event() {
+        global $DB;
+        $dg = $this->getDataGenerator();
+
+        // Create the data we need for the tests.
+        $u1 = $dg->create_user();
+        $u2 = $dg->create_user();
+        $c1 = $dg->create_course();
+        $a1 = $dg->create_module('assign', ['course' => $c1->id]);
+
+        $gi = new grade_item($dg->create_grade_item(
+            [
+                'courseid' => $c1->id,
+                'itemtype' => 'mod',
+                'itemmodule' => 'assign',
+                'iteminstance' => $a1->id
+            ]
+        ), false);
+
+        grade_update('mod/assign', $gi->courseid, $gi->itemtype, $gi->itemmodule, $gi->iteminstance,
+            $gi->itemnumber, ['userid' => $u1->id]);
+        grade_update('mod/assign', $gi->courseid, $gi->itemtype, $gi->itemmodule, $gi->iteminstance,
+            $gi->itemnumber, ['userid' => $u2->id]);
+
+        $gg = grade_grade::fetch(array('userid' => $u1->id, 'itemid' => $gi->id));
+        $this->assertEquals($u1->id, $gg->userid);
+        $gg->load_grade_item();
+        $this->assertEquals($gi->id, $gg->grade_item->id);
+
+        // Delete user with valid grade item.
+        $sink = $this->redirectEvents();
+        grade_user_delete($u1->id);
+        $events = $sink->get_events();
+        $event = reset($events);
+        $sink->close();
+        $this->assertInstanceOf('core\event\grade_deleted', $event);
+
+        $gg = grade_grade::fetch(array('userid' => $u2->id, 'itemid' => $gi->id));
+        $this->assertEquals($u2->id, $gg->userid);
+        $gg->load_grade_item();
+        $this->assertEquals($gi->id, $gg->grade_item->id);
+
+        // Delete grade item, mock up orphaned grade_grades.
+        $DB->delete_records('grade_items', ['id' => $gi->id]);
+        $gg = grade_grade::fetch(array('userid' => $u2->id, 'itemid' => $gi->id));
+        $this->assertEquals($u2->id, $gg->userid);
+
+        // No event is triggered and there is a debugging message.
+        $sink = $this->redirectEvents();
+        grade_user_delete($u2->id);
+        $this->assertDebuggingCalled("Missing grade item id $gi->id");
+        $events = $sink->get_events();
+        $sink->close();
+        $this->assertEmpty($events);
+
+        // The grade should be deleted.
+        $gg = grade_grade::fetch(array('userid' => $u2->id, 'itemid' => $gi->id));
+        $this->assertEmpty($gg);
+    }
 }