From 91e676ebde31bb19f902784dee7c727c673e547e Mon Sep 17 00:00:00 2001
From: Stefan Hanauska <stefan.hanauska@csg-in.de>
Date: Mon, 25 Aug 2025 19:52:37 +0200
Subject: [PATCH] MDL-86300 backup: Save old id of top category

Co-authored-by: Paola Maneggia <paola.maneggia@isb.bayern.de>
---
 backup/moodle2/restore_stepslib.php   |  2 +-
 backup/moodle2/tests/moodle2_test.php | 66 ++++++++++++++++++++++++++-
 2 files changed, 66 insertions(+), 2 deletions(-)

diff --git a/backup/moodle2/restore_stepslib.php b/backup/moodle2/restore_stepslib.php
index 09b2d036fbc..c34d3490413 100644
--- a/backup/moodle2/restore_stepslib.php
+++ b/backup/moodle2/restore_stepslib.php
@@ -5553,7 +5553,7 @@ class restore_move_module_questions_categories extends restore_execution_step {
                 // From 3.5 onwards, all question categories should be a child of a special category called the "top" category.
                 $info = backup_controller_dbops::decode_backup_temp_info($modulecat->info);
                 if ($after35 && empty($info->parent)) {
-                    $oldtopid = $modulecat->newitemid;
+                    $oldtopid = $modulecat->itemid;
                     $modulecat->newitemid = $top->id;
                 } else {
                     $cat = new stdClass();
diff --git a/backup/moodle2/tests/moodle2_test.php b/backup/moodle2/tests/moodle2_test.php
index 6b37f926058..a015c83e06a 100644
--- a/backup/moodle2/tests/moodle2_test.php
+++ b/backup/moodle2/tests/moodle2_test.php
@@ -1088,14 +1088,78 @@ final class moodle2_test extends \advanced_testcase {
                     }
                 }
 
-                // Make sure there is a single top level category in this context.
+                // Make sure there is a single top level category in this context and that the parents are set correctly.
                 if ($cats) {
                     $this->assertEquals(1, $topcategorycount[$context->id]);
+                    $topcat = array_values($cats)[0];
+                    $this->assertEquals(0, $topcat->parent);
+                    $othercat = array_values($cats)[1];
+                    $this->assertEquals($topcat->id, $othercat->parent);
                 }
             }
         }
     }
 
+    /**
+     * Check that the backup/restore process correctly wires the question categories, see MDL-86300.
+     * @covers \restore_move_module_questions_categories::define_execution
+     */
+    public function test_restore_question_categories_from_500(): void {
+        global $DB, $CFG, $USER;
+
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+
+        // Create a course.
+        $generator = $this->getDataGenerator();
+        $questiongenerator = $this->getDataGenerator()->get_plugin_generator('core_question');
+        $course = $generator->create_course();
+
+        // Add a quiz with question categories.
+        $quiz = $generator->create_module('quiz', ['course' => $course->id]);
+        $quizcontext = \context_module::instance($quiz->cmid);
+        $questiongenerator->create_question_category(['contextid' => $quizcontext->id]);
+        $quizquestioncats = $DB->get_records('question_categories', ['contextid' => $quizcontext->id]);
+        $this->assertCount(3, $quizquestioncats);
+
+        // Add a question bank with question categories.
+        $qbank = $this->getDataGenerator()->create_module('qbank', ['course' => $course->id]);
+        $qbankcontext = \context_module::instance($qbank->cmid);
+        $questiongenerator->create_question_category(['contextid' => $qbankcontext->id]);
+        $qbankquestioncats = $DB->get_records('question_categories', ['contextid' => $qbankcontext->id]);
+        $this->assertCount(3, $qbankquestioncats);
+
+        $targetcourseid = $this->backup_and_restore($course);
+
+        // Check the quiz and qbank question categories in the target course, in particular the parent relationship.
+        $modinfo = get_fast_modinfo($targetcourseid);
+
+        $targetquizzes = $modinfo->get_instances_of('quiz');
+        $this->assertCount(1, $targetquizzes);
+        $targetquiz = reset($targetquizzes);
+        $targetquizcontext = \context_module::instance($targetquiz->id);
+        $targetquizcats = array_values(
+            $DB->get_records('question_categories', ['contextid' => $targetquizcontext->id], 'parent', 'id, name, parent')
+        );
+        $this->assertCount(3, $targetquizcats);
+        $quiztop = $targetquizcats[0];
+        $this->assertEquals(0, $quiztop->parent);
+        $quiznontop = $targetquizcats[1];
+        $this->assertEquals($quiztop->id, $quiznontop->parent);
+
+        $targetqbanks = $modinfo->get_instances_of('qbank');
+        $this->assertCount(1, $targetqbanks);
+        $targetqbankcontext = \context_module::instance(reset($targetqbanks)->id);
+        $targetqbankcats = array_values(
+            $DB->get_records('question_categories', ['contextid' => $targetqbankcontext->id], 'parent', 'id, name, parent')
+        );
+        $this->assertCount(3, $targetqbankcats);
+        $qbanktop = $targetqbankcats[0];
+        $this->assertEquals(0, $qbanktop->parent);
+        $qbanknontop = $targetqbankcats[1];
+        $this->assertEquals($qbanktop->id, $qbanknontop->parent);
+    }
+
     /**
      * Test the content bank content through a backup and restore.
      */