From 7cf7e56a93a3726a60593b6c9de7a498ff7bdde5 Mon Sep 17 00:00:00 2001
From: Paul de Raaij <paul@paulderaaij.nl>
Date: Wed, 29 Jul 2026 01:46:58 -0400
Subject: [PATCH] feat: add DomainEvent base class and 5 domain event types

---
 domain/marketplace/__init__.py     |  6 +++
 domain/marketplace/domain_event.py | 36 +++++++++++++
 tests/test_domain_event.py         | 81 ++++++++++++++++++++++++++++++
 3 files changed, 123 insertions(+)
 create mode 100644 domain/marketplace/domain_event.py
 create mode 100644 tests/test_domain_event.py

diff --git a/domain/marketplace/__init__.py b/domain/marketplace/__init__.py
index 0eaf436..0475334 100644
--- a/domain/marketplace/__init__.py
+++ b/domain/marketplace/__init__.py
@@ -3,6 +3,12 @@ from .classified_ad_id import ClassifiedAdId as ClassifiedAdId
 from .classified_ad_state import ClassifiedAdState as ClassifiedAdState
 from .classified_ad_text import ClassifiedAdText as ClassifiedAdText
 from .classified_ad_title import ClassifiedAdTitle as ClassifiedAdTitle
+from .domain_event import ClassifiedAdCreated as ClassifiedAdCreated
+from .domain_event import ClassifiedAdPriceUpdated as ClassifiedAdPriceUpdated
+from .domain_event import ClassifiedAdSentForReview as ClassifiedAdSentForReview
+from .domain_event import ClassifiedAdTextUpdated as ClassifiedAdTextUpdated
+from .domain_event import ClassifiedAdTitleChanged as ClassifiedAdTitleChanged
+from .domain_event import DomainEvent as DomainEvent
 from .invalid_entity_state_exception import (
     InvalidEntityStateException as InvalidEntityStateException,
 )
diff --git a/domain/marketplace/domain_event.py b/domain/marketplace/domain_event.py
new file mode 100644
index 0000000..2392adb
--- /dev/null
+++ b/domain/marketplace/domain_event.py
@@ -0,0 +1,36 @@
+from dataclasses import dataclass
+from decimal import Decimal
+from uuid import UUID
+
+
+class DomainEvent:
+    pass
+
+
+@dataclass(frozen=True)
+class ClassifiedAdCreated(DomainEvent):
+    id: UUID
+    owner_id: UUID
+
+
+@dataclass(frozen=True)
+class ClassifiedAdTitleChanged(DomainEvent):
+    id: UUID
+    title: str
+
+
+@dataclass(frozen=True)
+class ClassifiedAdTextUpdated(DomainEvent):
+    id: UUID
+    ad_text: str
+
+
+@dataclass(frozen=True)
+class ClassifiedAdPriceUpdated(DomainEvent):
+    id: UUID
+    price: Decimal
+
+
+@dataclass(frozen=True)
+class ClassifiedAdSentForReview(DomainEvent):
+    id: UUID
diff --git a/tests/test_domain_event.py b/tests/test_domain_event.py
new file mode 100644
index 0000000..752a389
--- /dev/null
+++ b/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