Clock¶
A clock abstraction encapsulates the current time behind an interface, making code that depends on the current time testable with a controlled, deterministic value instead of the real system clock.
PSR-20 standardizes this with ClockInterface, which exposes a single method: now(): DateTimeImmutable. Rather than calling new DateTimeImmutable() or time() directly, a ClockInterface is injected as a dependency, giving tests full control over the perceived time.
PHP 8.3 introduced the native DateTimeImmutable::createFromTimestamp() method for testing purposes.
<?php
use Psr\Clock\ClockInterface;
final class Scheduler {
public function __construct(private readonly ClockInterface $clock) {}
public function isExpired(DateTimeImmutable $expiresAt): bool {
return $this->clock->now() > $expiresAt;
}
}
?>
See also PSR-20: Clock and Testing Time-Sensitive Code in PHP.
Related : DateTime, DateInterval, PHP Standards Recommendations (PSR), Dependency Injection, Test, Immutable, Interoperability
Related packages : psr/clock, symfony/clock
