feat: add DomainEvent base class and 5 domain event types

tests/test_domain_event.py

@@ -0,0 +1,81 @@
+from decimal import Decimal
+from uuid import uuid4
+
+from domain.marketplace.domain_event import (
+    ClassifiedAdCreated,
+    ClassifiedAdPriceUpdated,
+    ClassifiedAdSentForReview,
+    ClassifiedAdTextUpdated,
+    ClassifiedAdTitleChanged,
+    DomainEvent,
+)
+
+
+def test_classified_ad_created_creation():
+    event_id = uuid4()
+    owner_id = uuid4()
+
+    event = ClassifiedAdCreated(id=event_id, owner_id=owner_id)
+
+    assert event.id == event_id
+    assert event.owner_id == owner_id
+
+
+def test_classified_ad_title_changed_creation():
+    event_id = uuid4()
+
+    event = ClassifiedAdTitleChanged(id=event_id, title="New Title")
+
+    assert event.id == event_id
+    assert event.title == "New Title"
+
+
+def test_classified_ad_text_updated_creation():
+    event_id = uuid4()
+
+    event = ClassifiedAdTextUpdated(id=event_id, ad_text="Updated text")
+
+    assert event.id == event_id
+    assert event.ad_text == "Updated text"
+
+
+def test_classified_ad_price_updated_creation():
+    event_id = uuid4()
+
+    event = ClassifiedAdPriceUpdated(id=event_id, price=Decimal("99.99"))
+
+    assert event.id == event_id
+    assert event.price == Decimal("99.99")
+
+
+def test_classified_ad_sent_for_review_creation():
+    event_id = uuid4()
+
+    event = ClassifiedAdSentForReview(id=event_id)
+
+    assert event.id == event_id
+
+
+def test_domain_event_isinstance_check():
+    event = ClassifiedAdCreated(id=uuid4(), owner_id=uuid4())
+
+    assert isinstance(event, DomainEvent)
+
+
+def test_domain_events_are_immutable():
+    event = ClassifiedAdCreated(id=uuid4(), owner_id=uuid4())
+
+    try:
+        event.id = uuid4()  # type: ignore
+        assert False, "Should have raised FrozenInstanceError"
+    except AttributeError:
+        pass
+
+
+def test_domain_event_equality():
+    event_id = uuid4()
+
+    event1 = ClassifiedAdSentForReview(id=event_id)
+    event2 = ClassifiedAdSentForReview(id=event_id)
+
+    assert event1 == event2