first ruggedy draft

tests/test_settlement.py

@@ -0,0 +1,124 @@
+from __future__ import annotations
+
+from datetime import date
+from decimal import Decimal
+
+from mousehold_api import models
+from mousehold_api.services.settlement import calculate_settlement
+from mousehold_domain import FinancialEventStatus, FinancialEventType
+from sqlalchemy.orm import Session
+
+
+def test_equal_split_settlement(
+    session: Session,
+    household_setup: dict[str, str],
+) -> None:
+    event = models.FinancialEvent(
+        household_id=household_setup["household_id"],
+        payment_account_id=household_setup["account_a_id"],
+        payer_user_id=household_setup["user_a_id"],
+        event_type=FinancialEventType.EXPENSE,
+        status=FinancialEventStatus.CONFIRMED,
+        event_date=date(2026, 1, 1),
+        amount=Decimal("120.00"),
+        currency="EUR",
+        merchant="Groceries",
+    )
+    session.add(event)
+    session.flush()
+    session.add_all(
+        [
+            models.SplitLine(
+                event_id=event.id,
+                user_id=household_setup["user_a_id"],
+                share_amount=Decimal("60.00"),
+            ),
+            models.SplitLine(
+                event_id=event.id,
+                user_id=household_setup["user_b_id"],
+                share_amount=Decimal("60.00"),
+            ),
+        ]
+    )
+    session.commit()
+
+    summary = calculate_settlement(session, household_id=household_setup["household_id"])
+
+    assert len(summary.suggested_transfers) == 1
+    transfer = summary.suggested_transfers[0]
+    assert transfer.from_user_id == household_setup["user_b_id"]
+    assert transfer.to_user_id == household_setup["user_a_id"]
+    assert transfer.amount == Decimal("60.00")
+
+
+def test_shared_neutral_account_is_excluded(
+    session: Session,
+    household_setup: dict[str, str],
+) -> None:
+    event = models.FinancialEvent(
+        household_id=household_setup["household_id"],
+        payment_account_id=household_setup["shared_account_id"],
+        payer_user_id=household_setup["user_a_id"],
+        event_type=FinancialEventType.EXPENSE,
+        status=FinancialEventStatus.CONFIRMED,
+        event_date=date(2026, 1, 1),
+        amount=Decimal("100.00"),
+        currency="EUR",
+    )
+    session.add(event)
+    session.flush()
+    session.add_all(
+        [
+            models.SplitLine(
+                event_id=event.id,
+                user_id=household_setup["user_a_id"],
+                share_amount=Decimal("50.00"),
+            ),
+            models.SplitLine(
+                event_id=event.id,
+                user_id=household_setup["user_b_id"],
+                share_amount=Decimal("50.00"),
+            ),
+        ]
+    )
+    session.commit()
+
+    summary = calculate_settlement(session, household_id=household_setup["household_id"])
+
+    assert summary.included_event_ids == []
+    assert summary.excluded_event_ids == [event.id]
+    assert summary.suggested_transfers == []
+
+
+def test_announced_and_outstanding_are_excluded_by_default(
+    session: Session,
+    household_setup: dict[str, str],
+) -> None:
+    event = models.FinancialEvent(
+        household_id=household_setup["household_id"],
+        payment_account_id=household_setup["account_a_id"],
+        payer_user_id=household_setup["user_a_id"],
+        event_type=FinancialEventType.EXPENSE,
+        status=FinancialEventStatus.OUTSTANDING,
+        event_date=date(2026, 1, 1),
+        amount=Decimal("80.00"),
+        currency="EUR",
+    )
+    session.add(event)
+    session.flush()
+    session.add(
+        models.SplitLine(
+            event_id=event.id, user_id=household_setup["user_b_id"], share_amount=Decimal("80.00")
+        )
+    )
+    session.commit()
+
+    default_summary = calculate_settlement(session, household_id=household_setup["household_id"])
+    forecast_summary = calculate_settlement(
+        session,
+        household_id=household_setup["household_id"],
+        include_announced=True,
+    )
+
+    assert default_summary.suggested_transfers == []
+    assert forecast_summary.suggested_transfers[0].amount == Decimal("80.00")