Add test for forgetting rooms on leave

Signed-off-by: Sean Quah <[email protected]>

tests/handlers/test_room_member.py

@@ -333,6 +333,17 @@ def test_leave_and_forget(self) -> None:
             self.get_success(self.store.is_locally_forgotten_room(self.room_id))
         )
 
+    @override_config({"forget_rooms_on_leave": True})
+    def test_leave_and_auto_forget(self) -> None:
+        """Tests the `forget_rooms_on_leave` config option."""
+        self.helper.join(self.room_id, user=self.bob, tok=self.bob_token)
+
+        # alice is not the last room member that leaves and forgets the room
+        self.helper.leave(self.room_id, user=self.alice, tok=self.alice_token)
+        self.assertTrue(
+            self.get_success(self.store.did_forget(self.alice, self.room_id))
+        )
+
     def test_leave_and_forget_last_user(self) -> None:
         """Tests that forget a room is successfully when the last user has left the room."""