fix: TT-418 code smell resolved

V2/tests/integration/daos/customers_dao_test.py

@@ -128,7 +128,7 @@ def test__update_customer_dao__returns_an_updated_customer_dto__when_updates_cor
     assert updated_customer.__dict__ == inserted_customer
 
 
-def test__update_customer_dao__returns_None__when_an_incorrect_id_is_passed(
+def test__update_customer_dao__returns_none__when_an_incorrect_id_is_passed(
     test_db, customer_factory, create_fake_dao, insert_customer
 ):
     dao = create_fake_dao(test_db)

V2/time_tracker/customers/_application/_customers/_create_customer.py

@@ -51,6 +51,6 @@ def create_customer(req: func.HttpRequest) -> func.HttpResponse:
         )
 
 
-def _validate_customer(customer_data: dict) -> bool:
+def _validate_customer(customer_data: dict) -> typing.List[str]:
     return [field.name for field in dataclasses.fields(_domain.Customer)
             if (field.name not in customer_data) and (field.type != typing.Optional[field.type])]