finalized helper functions for category trees; started writing tests

tests/test_transactions.py

@@ -101,7 +101,7 @@ def test_map_comdirect_giro_to_transaction():
     assert transaction.amount == Decimal("32.43")
     assert transaction.other_name is None
     assert transaction.other_iban is None
-    assert transaction.category_id is None
+    assert transaction.category is None
 
 
 def test_consolidate_b4w_signed_amount_and_category(db_session: Session):
@@ -125,6 +125,9 @@ def test_consolidate_b4w_signed_amount_and_category(db_session: Session):
     assert transaction.amount == Decimal("-50.00")
     assert transaction.category_id == staging.category_id
     assert transaction.text == "Supermarket"
+    mapped = map_b4w_to_transaction(staging)
+    assert mapped.category is not None
+    assert mapped.category.to_str() == export.category.to_str()
 
 
 def test_ingest_b4w_e2e_idempotent(db_session: Session):