def remove(self, db_conn: DatabaseConnection) -> None:
         """Remove from DB and cache."""
-        assert isinstance(self.id_, int | str)
+        if self.id_ is None or self.__class__.get_cached(self.id_) is None:
+            raise HandledException('cannot remove unsaved item')
         self.uncache()
         db_conn.delete_where(self.table_name, 'id', self.id_)
 
 from datetime import datetime
 from tests.utils import TestCaseWithDB, TestCaseWithServer
 from plomtask.days import Day, todays_date
-from plomtask.exceptions import BadFormatException, NotFoundException
+from plomtask.exceptions import (BadFormatException, NotFoundException,
+                                 HandledException)
 
 
 class TestsSansDB(TestCase):
         self.assertEqual(day.id_, date)
         self.assertEqual(day.comment, comment)
 
+    def test_Day_from_table_row(self) -> None:
+        """Test .from_table_row() properly reads in class from DB"""
+        day = Day('2024-01-01')
+        day.save(self.db_conn)
+        assert isinstance(day.id_, str)
+        for row in self.db_conn.row_where(Day.table_name, 'id', day.id_):
+            retrieved = Day.from_table_row(self.db_conn, row)
+            self.assertEqual(day, retrieved)
+            self.assertEqual({day.id_: day}, Day.get_cache())
+
     def test_Day_by_id(self) -> None:
         """Test .by_id()."""
         date1 = '2024-01-01'
         day1 = Day(date1)
         day2 = Day(date2)
         day3 = Day(date3)
+        # check pre-save .all() returns empty list
+        self.assertEqual(Day.all(self.db_conn), [])
+        # check that all() shows all saved, but no unsaved items
         day1.save(self.db_conn)
         day3.save(self.db_conn)
-        # check that all() shows all saved, but no unsaved items
         self.assertEqual(Day.all(self.db_conn),
                          [day1, day3])
         day2.save(self.db_conn)
         """Test .remove() effects on DB and cache."""
         date = '2024-01-01'
         day = Day(date)
+        with self.assertRaises(HandledException):
+            day.remove(self.db_conn)
         day.save(self.db_conn)
         day.remove(self.db_conn)
         self.check_storage([])