The Clock

Clock is simple implementation of PSR-20 Clock. It allows to set a clock with a timezone for generated dates.

Clock has a param to set timezone:

$clock = new SystemClock('Europe/London')

Thanks to Clock in your extension (look at DateTime for example) you will have access to $this->clock->now() that will return \DateTimeImmutable object with current date time.

If no timezone param is passed it checks for date_default_timezone_get() and if it's missing then UTC timezone is used. But date_default_timezone_get() is returning UTC as default anyway.

Generator itself can return clock so you can do this to get current time:

$generator->clock->now();

There is also FrozenClock ready to be used in tests - you can set it with fixed date:

$clock = new FrozenClock(new \DateTimeImmutable('2025-08-11'), new \DateTimeZone('UTC'));
$generator = new DummyGenerator(DefinitionContainerBuilder::all(), new SimpleStragegy(), $clock)
// or
$generator = DummyGeneratorFactory::create();
$generator = $generator->withClock($clock);