Add and extend test coverage for models and their methods

Enhanced test coverage includes `repr` methods, model functionality, and validation logic for key models like `GiftItem`, `GiftCategory`, `EventMedia`, `RSVP`, and `GiftPurchase`. Refactored and added fixtures to support comprehensive testing scenarios. Addresses validation for gift reordering and updates `EventMedia` representation format for consistency.

backend/tests/conftest.py

@@ -4,7 +4,8 @@ from datetime import datetime, timezone
 
 import pytest
 
-from app.models import GiftItem, GiftStatus, GiftPriority, RSVP, RSVPStatus, EventMedia, MediaType, MediaPurpose, \
+from app.models import Event, GiftItem, GiftStatus, GiftPriority, GiftCategory, GiftPurchase, RSVP, RSVPStatus, \
+    EventMedia, MediaType, MediaPurpose, \
     EventTheme, Guest, GuestStatus, ActivityType, ActivityLog, EmailTemplate, TemplateType, NotificationLog, \
     NotificationType, NotificationStatus
 from app.models.user import User
@@ -47,6 +48,31 @@ def mock_user(db_session):
     return mock_user
 
 
+@pytest.fixture
+def event_fixture(db_session, mock_user):
+    """
+    Fixture to create and return an Event instance with valid data.
+    """
+    event = Event(
+        id=uuid.uuid4(),
+        title="Birthday Party",
+        slug="birthday-party-1",  # Required unique slug
+        description="A special 1st birthday celebration event.",
+        event_date=datetime(2023, 12, 25, tzinfo=timezone.utc),
+        timezone="UTC",  # Required timezone
+        created_by=mock_user.id,  # Reference to a valid mock_user
+        is_public=False,  # Default value
+        is_active=True,  # Default value
+        rsvp_enabled=False,  # Default value
+        gift_registry_enabled=True,  # Default value
+        updates_enabled=True  # Default value
+    )
+    db_session.add(event)
+    db_session.commit()
+    return event
+
+
+
 @pytest.fixture
 def gift_item_fixture(db_session, mock_user):
     """
@@ -219,6 +245,7 @@ def email_template_fixture(db_session, mock_user):
     db_session.commit()
     return email_template
 
+
 @pytest.fixture
 def notification_log_fixture(db_session, email_template_fixture, guest_fixture):
     """
@@ -238,4 +265,43 @@ def notification_log_fixture(db_session, email_template_fixture, guest_fixture):
     )
     db_session.add(notification_log)
     db_session.commit()
-    return notification_log
+    return notification_log
+
+
+@pytest.fixture
+def gift_purchase_fixture(db_session, gift_item_fixture, guest_fixture):
+    """
+    Fixture to create and return a GiftPurchase instance.
+    """
+    gift_purchase = GiftPurchase(
+        id=uuid.uuid4(),
+        gift_id=gift_item_fixture.id,
+        guest_id=guest_fixture.id,
+        quantity=1,
+        purchased_at=datetime.now(timezone.utc),
+        purchase_price=25.0,
+        purchase_currency="USD",
+        notes="Gift purchased through store link"
+    )
+    db_session.add(gift_purchase)
+    db_session.commit()
+    return gift_purchase
+
+
+@pytest.fixture
+def gift_category_fixture(db_session, mock_user, event_fixture):
+    """
+    Fixture to create and return a GiftCategory instance.
+    """
+    gift_category = GiftCategory(
+        id=uuid.uuid4(),
+        name="Electronics",
+        description="Category for electronic gifts",
+        event_id=event_fixture.id,
+        created_by=mock_user.id,
+        display_order=0,
+        is_visible=True
+    )
+    db_session.add(gift_category)
+    db_session.commit()
+    return gift_category