From 72a51148e976f95ca6ea9feec6bd18e1a55addb2 Mon Sep 17 00:00:00 2001
From: Andrew Nicols <andrew@nicols.co.uk>
Date: Tue, 4 Apr 2023 09:25:04 +0800
Subject: [PATCH 1/3] MDL-77837 cron: Ensure user is set when running tasks

We should be proactive in ensuring that the environment is clean when
running a task. We already ensure that we have a clean renderer and
other parts of the output chain, but we were not setting a clean user.

This change adds a call to setup the cron user before each task is
actually executed.
---
 lib/cronlib.php | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/cronlib.php b/lib/cronlib.php
index a0d37334de2..21a71603b75 100644
--- a/lib/cronlib.php
+++ b/lib/cronlib.php
@@ -242,6 +242,10 @@ function cron_run_inner_scheduled_task(\core\task\task_base $task) {
     $predbqueries = null;
     $predbqueries = $DB->perf_get_queries();
     $pretime = microtime(1);
+
+    // Ensure that we have a clean session with the correct cron user.
+    cron_setup_user();
+
     try {
         get_mailer('buffer');
         cron_prepare_core_renderer();
@@ -325,6 +329,10 @@ function cron_run_inner_adhoc_task(\core\task\adhoc_task $task) {
         }
 
         cron_setup_user($user);
+    } else {
+        // No user specified, ensure that we have a clean session with the correct cron user.
+        cron_setup_user();
+
     }
 
     try {

From 22ac74f686cceab3dd1b92ec9e867e378493435d Mon Sep 17 00:00:00 2001
From: Andrew Nicols <andrew@nicols.co.uk>
Date: Tue, 4 Apr 2023 09:26:34 +0800
Subject: [PATCH 2/3] MDL-77837 phpunit: Ensure that the cron user setter is
 used

When running an adhoc task in a unit test we should use the cron variant
of the set user method to mimic the behaviour of a real cron run.
---
 lib/phpunit/classes/advanced_testcase.php     |  2 +-
 lib/phpunit/tests/advanced_test.php           | 54 +++++++++++++++++++
 .../tests/fixtures/adhoc_test_task.php        | 35 ++++++++++++
 3 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 lib/phpunit/tests/fixtures/adhoc_test_task.php

diff --git a/lib/phpunit/classes/advanced_testcase.php b/lib/phpunit/classes/advanced_testcase.php
index 41a7da01b1e..7420ce40ab6 100644
--- a/lib/phpunit/classes/advanced_testcase.php
+++ b/lib/phpunit/classes/advanced_testcase.php
@@ -702,7 +702,7 @@ abstract class advanced_testcase extends base_testcase {
             }
 
             cron_prepare_core_renderer();
-            $this->setUser($user);
+            cron_setup_user($user);
 
             $task->execute();
             \core\task\manager::adhoc_task_complete($task);
diff --git a/lib/phpunit/tests/advanced_test.php b/lib/phpunit/tests/advanced_test.php
index 525325d2a38..769072a5516 100644
--- a/lib/phpunit/tests/advanced_test.php
+++ b/lib/phpunit/tests/advanced_test.php
@@ -33,8 +33,13 @@ defined('MOODLE_INTERNAL') || die();
  * @category   phpunit
  * @copyright  2012 Petr Skoda {@link http://skodak.org}
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @coversDefaultClass \advanced_testcase
  */
 class core_phpunit_advanced_testcase extends advanced_testcase {
+    public static function setUpBeforeClass(): void {
+        global $CFG;
+        require_once(__DIR__ . '/fixtures/adhoc_test_task.php');
+    }
 
     public function test_debugging() {
         global $CFG;
@@ -680,4 +685,53 @@ class core_phpunit_advanced_testcase extends advanced_testcase {
         self::resetAllData(false);
         self::assertFalse(core_useragent::get_user_agent_string(), 'It should not be set again, data was reset.');
     }
+
+    /**
+     * @covers ::runAdhocTasks
+     */
+    public function test_runadhoctasks_no_tasks_queued(): void {
+        $this->runAdhocTasks();
+        $this->expectOutputRegex('/^$/');
+    }
+
+    /**
+     * @covers ::runAdhocTasks
+     */
+    public function test_runadhoctasks_tasks_queued(): void {
+        $this->resetAfterTest(true);
+        $admin = get_admin();
+        \core\task\manager::queue_adhoc_task(new \core_phpunit\adhoc_test_task());
+        $this->runAdhocTasks();
+        $this->expectOutputRegex("/Task was run as {$admin->id}/");
+    }
+
+    /**
+     * @covers ::runAdhocTasks
+     */
+    public function test_runadhoctasks_with_existing_user_change(): void {
+        $this->resetAfterTest(true);
+        $admin = get_admin();
+
+        $this->setGuestUser();
+        \core\task\manager::queue_adhoc_task(new \core_phpunit\adhoc_test_task());
+        $this->runAdhocTasks();
+        $this->expectOutputRegex("/Task was run as {$admin->id}/");
+    }
+
+    /**
+     * @covers ::runAdhocTasks
+     */
+    public function test_runadhoctasks_with_existing_user_change_and_specified(): void {
+        global $USER;
+
+        $this->resetAfterTest(true);
+        $user = $this->getDataGenerator()->create_user();
+
+        $this->setGuestUser();
+        $task = new \core_phpunit\adhoc_test_task();
+        $task->set_userid($user->id);
+        \core\task\manager::queue_adhoc_task($task);
+        $this->runAdhocTasks();
+        $this->expectOutputRegex("/Task was run as {$user->id}/");
+    }
 }
diff --git a/lib/phpunit/tests/fixtures/adhoc_test_task.php b/lib/phpunit/tests/fixtures/adhoc_test_task.php
new file mode 100644
index 00000000000..090650fdc0c
--- /dev/null
+++ b/lib/phpunit/tests/fixtures/adhoc_test_task.php
@@ -0,0 +1,35 @@
+<?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/>.
+
+namespace core_phpunit;
+
+/**
+ * Fixtures for task tests.
+ *
+ * @package    core
+ * @category   phpunit
+ * @copyright  2023 Andrew Lyons <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class adhoc_test_task extends \core\task\adhoc_task {
+    /**
+     * Execute.
+     */
+    public function execute() {
+        global $USER;
+        mtrace("Task was run as {$USER->id}");
+    }
+}

From d1f085a771da29d223e5377f288f1f8774eb5797 Mon Sep 17 00:00:00 2001
From: Andrew Nicols <andrew@nicols.co.uk>
Date: Thu, 6 Apr 2023 16:26:38 +0800
Subject: [PATCH 3/3] MDL-77837 core: Improve usage docs for cron_setup_user

---
 lib/sessionlib.php | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/sessionlib.php b/lib/sessionlib.php
index 59e2e6aa51f..e465d7dff2c 100644
--- a/lib/sessionlib.php
+++ b/lib/sessionlib.php
@@ -170,7 +170,11 @@ function get_moodle_cookie() {
 
 /**
  * Sets up current user and course environment (lang, etc.) in cron.
- * Do not use outside of cron script!
+ * Note: This function is intended only for use in:
+ * - the cron runner scripts
+ * - individual tasks which extend the adhoc_task and scheduled_task classes
+ * - unit tests related to tasks
+ * - other parts of the cron/task system
  *
  * @param stdClass $user full user object, null means default cron user (admin),
  *                 value 'reset' means reset internal static caches.