عرض عملي: حقن Clock لاختبار منطق يعتمد على الوقت

خطوة بخطوة

1. Show PromotionService calling LocalDate.now(); the test passes only on certain days.
2. Add a Clock bean in a @Configuration class.
3. Inject Clock through the constructor and use LocalDate.now(clock).
4. Planned mistake: leave one static Instant.now() in another service; the test still flakes. Fix: search for now() and replace.
5. In the test use Clock.fixed(...) and assert both sides of the deadline.