From fe3441d95f79e4be01ac5c0c24c8a265e3637367 Mon Sep 17 00:00:00 2001
From: Paul Holden <paulh@moodle.com>
Date: Tue, 19 Oct 2021 21:01:52 +0100
Subject: [PATCH] MDL-72743 mod_quiz: verify user mapping prior to restoring
 attempts.

---
 .../backup/moodle2/restore_quiz_stepslib.php  |  17 ++-
 .../question_attempts_missing_users.mbz       | Bin 0 -> 12535 bytes
 mod/quiz/tests/restore_attempt_test.php       | 101 ++++++++++++++++++
 3 files changed, 117 insertions(+), 1 deletion(-)
 create mode 100644 mod/quiz/tests/fixtures/question_attempts_missing_users.mbz
 create mode 100644 mod/quiz/tests/restore_attempt_test.php

diff --git a/mod/quiz/backup/moodle2/restore_quiz_stepslib.php b/mod/quiz/backup/moodle2/restore_quiz_stepslib.php
index 6bdb81376ff..3b5fc42ad03 100644
--- a/mod/quiz/backup/moodle2/restore_quiz_stepslib.php
+++ b/mod/quiz/backup/moodle2/restore_quiz_stepslib.php
@@ -40,6 +40,9 @@ class restore_quiz_activity_structure_step extends restore_questions_activity_st
      */
     protected $sectioncreated = false;
 
+    /** @var stdClass|null $currentquizattempt Track the current quiz attempt being restored. */
+    protected $currentquizattempt = null;
+
     /**
      * @var bool when restoring old quizzes (2.8 or before) this records the
      * shufflequestionsoption quiz option which has moved to the quiz_sections table.
@@ -453,7 +456,16 @@ class restore_quiz_activity_structure_step extends restore_questions_activity_st
         $data->quiz = $this->get_new_parentid('quiz');
         $data->attempt = $data->attemptnum;
 
-        $data->userid = $this->get_mappingid('user', $data->userid);
+        // Get user mapping, return early if no mapping found for the quiz attempt.
+        $olduserid = $data->userid;
+        $data->userid = $this->get_mappingid('user', $olduserid, 0);
+        if ($data->userid === 0) {
+            $this->log('Mapped user ID not found for user ' . $olduserid . ', quiz ' . $this->get_new_parentid('quiz') .
+                ', attempt ' . $data->attempt . '. Skipping quiz attempt', backup::LOG_INFO);
+
+            $this->currentquizattempt = null;
+            return;
+        }
 
         if (!empty($data->timecheckstate)) {
             $data->timecheckstate = $this->apply_date_offset($data->timecheckstate);
@@ -488,6 +500,9 @@ class restore_quiz_activity_structure_step extends restore_questions_activity_st
         global $DB;
 
         $data = $this->currentquizattempt;
+        if ($data === null) {
+            return;
+        }
 
         $oldid = $data->id;
         $data->uniqueid = $newusageid;
diff --git a/mod/quiz/tests/fixtures/question_attempts_missing_users.mbz b/mod/quiz/tests/fixtures/question_attempts_missing_users.mbz
new file mode 100644
index 0000000000000000000000000000000000000000..2ddc2a66f593888eacec4c727508fd4ce86b2053
GIT binary patch
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diff --git a/mod/quiz/tests/restore_attempt_test.php b/mod/quiz/tests/restore_attempt_test.php
new file mode 100644
index 00000000000..71492d0cdb5
--- /dev/null
+++ b/mod/quiz/tests/restore_attempt_test.php
@@ -0,0 +1,101 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Unit tests restoring quiz attempts
+ *
+ * @package     mod_quiz
+ * @copyright   2021 Paul Holden <paulh@moodle.com>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class mod_quiz_restore_attempt_test extends advanced_testcase {
+
+    /**
+     * Load required libraries
+     */
+    public static function setUpBeforeClass(): void {
+        global $CFG;
+
+        require_once("{$CFG->dirroot}/backup/util/includes/restore_includes.php");
+    }
+
+    /**
+     * Test restore dates.
+     */
+    public function test_restore_question_attempts_missing_users(): void {
+        global $DB, $USER;
+
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        // Contains a quiz with four attempts from different users. The users are as follows (user ID -> user):
+        // 3 -> User 01, 4 -> User 02, 5 -> User 03, 6 -> User 04.
+        // The user details for User 02 and User 03 have been removed from the backup file.
+        $testfixture = __DIR__ . '/fixtures/question_attempts_missing_users.mbz';
+
+        // Extract our test fixture, ready to be restored.
+        $backuptempdir = 'aaa';
+        $backuppath = make_backup_temp_directory($backuptempdir);
+        get_file_packer('application/vnd.moodle.backup')->extract_to_pathname($testfixture, $backuppath);
+
+        // Do the restore to new course with default settings.
+        $categoryid = $DB->get_field('course_categories', 'MIN(id)', []);
+        $courseid = restore_dbops::create_new_course('Test fullname', 'Test shortname', $categoryid);
+
+        $controller = new restore_controller($backuptempdir, $courseid, backup::INTERACTIVE_NO, backup::MODE_GENERAL, $USER->id,
+            backup::TARGET_NEW_COURSE);
+
+        $this->assertTrue($controller->execute_precheck());
+        $controller->execute_plan();
+        $controller->destroy();
+
+        // Grade restore also generates some debugging.
+        $this->assertDebuggingCalledCount(2);
+
+        $restoredquiz = $DB->get_record('quiz', []);
+
+        // Assert logs were added for User 02 and User 03, due to missing mapping lookup.
+        $loginfomessages = $DB->get_fieldset_select('backup_logs', 'message', 'backupid = ? AND loglevel = ?', [
+            $controller->get_restoreid(),
+            backup::LOG_INFO,
+        ]);
+
+        $this->assertContains("Mapped user ID not found for user 4, quiz {$restoredquiz->id}, attempt 1. Skipping quiz attempt",
+            $loginfomessages);
+        $this->assertContains("Mapped user ID not found for user 5, quiz {$restoredquiz->id}, attempt 1. Skipping quiz attempt",
+            $loginfomessages);
+
+        // User 01 has supplied the wrong answer, assert dates match the backup file too.
+        $user01attempt = $DB->get_record('quiz_attempts', [
+            'quiz' => $restoredquiz->id,
+            'userid' => core_user::get_user_by_username('user01')->id,
+        ]);
+
+        $this->assertEquals(1634751274, $user01attempt->timestart);
+        $this->assertEquals(1634751290, $user01attempt->timefinish);
+        $this->assertEquals(0.0, (float) $user01attempt->sumgrades);
+
+        // User 04 has supplied the correct answer, assert dates match the backup file too.
+        $user04attempt = $DB->get_record('quiz_attempts', [
+            'quiz' => $restoredquiz->id,
+            'userid' => core_user::get_user_by_username('user04')->id,
+        ]);
+
+        $this->assertEquals(1634751341, $user04attempt->timestart);
+        $this->assertEquals(1634751347, $user04attempt->timefinish);
+        $this->assertEquals(1.0, (float) $user04attempt->sumgrades);
+    }
+}