From 253c16b64d568d5114c4ab29554366ef4070d644 Mon Sep 17 00:00:00 2001
From: Andrew Nicols <andrew@nicols.co.uk>
Date: Tue, 14 May 2024 14:12:34 +0800
Subject: [PATCH] MDL-81894 core: system_clock should use the server timezone

---
 lib/classes/system_clock.php    |  7 +++++-
 lib/tests/system_clock_test.php | 44 +++++++++++++++++++++++++++++++++
 lib/upgrade.txt                 |  4 +++
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/lib/classes/system_clock.php b/lib/classes/system_clock.php
index 32cee16898d..ba80e0e7814 100644
--- a/lib/classes/system_clock.php
+++ b/lib/classes/system_clock.php
@@ -24,10 +24,15 @@ namespace core;
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class system_clock implements clock {
+    #[\Override]
     public function now(): \DateTimeImmutable {
-        return new \DateTimeImmutable();
+        return new \DateTimeImmutable(
+            datetime: "now",
+            timezone: \core_date::get_server_timezone_object(),
+        );
     }
 
+    #[\Override]
     public function time(): int {
         return $this->now()->getTimestamp();
     }
diff --git a/lib/tests/system_clock_test.php b/lib/tests/system_clock_test.php
index c8f5555303d..1282e743b0c 100644
--- a/lib/tests/system_clock_test.php
+++ b/lib/tests/system_clock_test.php
@@ -26,6 +26,9 @@ namespace core;
  * @covers \core\system_clock
  */
 final class system_clock_test extends \advanced_testcase {
+    /**
+     * Test that the now method returns a DateTimeImmutable object.
+     */
     public function test_now(): void {
         $starttime = time();
 
@@ -34,4 +37,45 @@ final class system_clock_test extends \advanced_testcase {
         $this->assertInstanceOf(\DateTimeImmutable::class, $now);
         $this->assertGreaterThanOrEqual($starttime, $now->getTimestamp());
     }
+
+    /**
+     * Test that the time method returns a timestamp.
+     */
+    public function test_time(): void {
+        $starttime = time();
+
+        $clock = new system_clock();
+        $time = $clock->time();
+        $this->assertGreaterThanOrEqual($starttime, $time);
+    }
+
+    /**
+     * Test that the now method returns a DateTimeImmutable object in the server timezone.
+     *
+     * @dataProvider timezone_provider
+     * @param string $timezone
+     */
+    public function test_now_timezone(string $timezone): void {
+        global $CFG;
+        $this->resetAfterTest();
+
+        $CFG->timezone = $timezone;
+
+        $clock = new system_clock();
+        $now = $clock->now();
+        $this->assertEquals(\core_date::normalise_timezone($CFG->timezone), $now->getTimezone()->getName());
+    }
+
+    /**
+     * Data provider for the test_now_timezone method.
+     *
+     * @return array
+     */
+    public static function timezone_provider(): array {
+        return [
+            ['UTC'],
+            ['Europe/London'],
+            ['America/New_York'],
+        ];
+    }
 }
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index 32f3e444bb9..3f180ecd79b 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -1,6 +1,10 @@
 This files describes API changes in core libraries and APIs,
 information provided here is intended especially for developers.
 
+=== 4.4.1 ===
+
+* Use server timezone when constructing `\DateTimeImmutable` for the system `\core\clock` implementation.
+
 === 4.4 ===
 
 * New modinfo methods related to delegated sections (sections controlled by a component):