Refactor: Refresh FakeService.last_id in dedicated function

Signed-off-by: Mathias L. Baumann <[email protected]>

Author: Marenz

src/frequenz/client/dispatch/test/_service.py

@@ -73,6 +73,17 @@ def __init__(self) -> None:
         self._last_id: DispatchId = DispatchId(0)
         """Last used dispatch id."""
 
+    def refresh_last_id_for(self, microgrid_id: MicrogridId) -> None:
+        """Update last id to be the next highest number."""
+        dispatches = self.dispatches.get(microgrid_id, [])
+
+        if len(dispatches) == 0:
+            return
+
+        self._last_id = DispatchId(
+            max(int(self._last_id), max(int(dispatch.id) for dispatch in dispatches))
+        )
+
     def _check_access(self, metadata: grpc.aio.Metadata) -> None:
         """Check if the access key is valid.
 

src/frequenz/client/dispatch/test/client.py

@@ -55,16 +55,7 @@ def set_dispatches(self, microgrid_id: MicrogridId, value: list[Dispatch]) -> No
             value: The list of dispatches to set.
         """
         self._service.dispatches[microgrid_id] = value
-
-        if len(value) == 0:
-            return
-
-        # Max between last id and the max id in the list
-        # pylint: disable=protected-access
-        self._service._last_id = max(
-            self._service._last_id, max(dispatch.id for dispatch in value)
-        )
-        # pylint: enable=protected-access
+        self._service.refresh_last_id_for(microgrid_id)
 
     @property
     def _service(self) -> FakeService: