diff --git a/src/server/BreCal/schemas/model.py b/src/server/BreCal/schemas/model.py
index 395905b..5130c9c 100644
--- a/src/server/BreCal/schemas/model.py
+++ b/src/server/BreCal/schemas/model.py
@@ -507,10 +507,10 @@ class User:
     user_phone: str
     password_hash: str
     api_key: str
-    notify_email: bool # #TODO_clarify: should we use an IntFlag for multi-assignment?
-    notify_whatsapp: bool # #TODO_clarify: should we use an IntFlag for multi-assignment?
-    notify_signal: bool # #TODO_clarify: should we use an IntFlag for multi-assignment?
-    notify_popup: bool # #TODO_clarify: should we use an IntFlag for multi-assignment?
+    notify_email: bool
+    notify_whatsapp: bool
+    notify_signal: bool
+    notify_popup: bool
     created: datetime
     modified: datetime
 
diff --git a/src/server/BreCal/validators/time_logic.py b/src/server/BreCal/validators/time_logic.py
index 8ebad56..8a0e592 100644
--- a/src/server/BreCal/validators/time_logic.py
+++ b/src/server/BreCal/validators/time_logic.py
@@ -76,8 +76,17 @@ class TimeLogic():
         minute_delta = delta / np.timedelta64(1, unit)
         return minute_delta
     
-    def time_delta_from_now_to_tgt(self, tgt_time, unit="m"):
-        return self.time_delta(datetime.datetime.now(), tgt_time=tgt_time, unit=unit)
+    def time_delta_from_now_to_tgt(self, tgt_time, unit="m", now_time=None):
+        """
+        This method computes the timedelta between a target time {tgt_time} and the current timestamp. For the purpose of 
+        reproducibility and testing, the current timestamp {now_time} can be overwritten. The default behaviour uses the 
+        datetime.now() function.
+        """
+        if now_time is None:
+            return self.time_delta(datetime.datetime.now(), tgt_time=tgt_time, unit=unit)
+        else:
+            assert isinstance(now_time,datetime.datetime), f"incorrect type for now_time: {now_time} with type {type(now_time)}"
+            return self.time_delta(now_time, tgt_time=tgt_time, unit=unit)
     
     def time_inbetween(self, query_time:datetime.datetime, start_time:datetime.datetime, end_time:datetime.datetime) -> bool:
         """