Add Clock classes to deal with "now" times in tests

- [Composer] Add psr/clock dependency

src/Util/Clock/SystemClock.php

@@ -0,0 +1,48 @@
+<?php
+/**
+ * @copyright Copyright (C) 2010-2022, the Friendica project
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Friendica\Util\Clock;
+
+use DateTimeImmutable;
+use DateTimeZone;
+
+/**
+ * Inspired by lcobucci/clock
+ * @see https://github.com/lcobucci/clock
+ */
+final class SystemClock implements \Psr\Clock\ClockInterface
+{
+	/** @var DateTimeZone */
+	private $timezone;
+
+	public function __construct(DateTimeZone $timezone = null)
+	{
+		$this->timezone = $timezone ?? new DateTimeZone('UTC');
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function now(): DateTimeImmutable
+	{
+		return new DateTimeImmutable('now', $this->timezone);
+	}
+}