Fix scenario alternatives not removed correctly (#2834)

* Fix scenario alternatives not removed correctly

When deletions were made in a scenario so that the rank order changed,
all the scenario alternatives were not removed. This caused an error
when the updated scen alt with the new rank number was attempted to
be added back to the db.

* Back to default requirements

tests/test_SpineDBManager.py

@@ -15,6 +15,7 @@
 from pathlib import Path
 from tempfile import TemporaryDirectory
 import unittest
+from unittest import mock
 from unittest.mock import MagicMock
 from PySide6.QtCore import Qt, QSettings
 from PySide6.QtWidgets import QApplication
@@ -556,5 +557,54 @@ def test_updating_indexed_value_changes_the_unparsed_value_in_database(self):
         self.assertEqual(update_value, Map(["a"], ["c"]))
 
 
+class TestRemoveScenarioAlternative(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        if not QApplication.instance():
+            QApplication()
+
+    def setUp(self):
+        mock_settings = MagicMock()
+        mock_settings.value.side_effect = lambda *args, **kwargs: 0
+        self._db_mngr = SpineDBManager(mock_settings, None)
+        self._logger = MagicMock()
+        self._db_map = self._db_mngr.get_db_map("sqlite://", self._logger, codename="database", create=True)
+
+    def tearDown(self):
+        self._db_mngr.close_all_sessions()
+        while not self._db_map.closed:
+            QApplication.processEvents()
+        self._db_mngr.clean_up()
+
+    def _assert_success(self, result):
+        item, error = result
+        self.assertIsNone(error)
+        return item
+
+    def test_removing_scenario_alternative_and_committing(self):
+        """Test that removing non-rank 1 scenario alternative works."""
+        scenario = self._assert_success(self._db_map.add_scenario_item(name="scenario"))
+        base = self._db_map.get_alternative_item(name="Base")
+        next_level = self._assert_success(self._db_map.add_alternative_item(name="Next level"))
+        scen_alt_1 = self._assert_success(
+            self._db_map.add_scenario_alternative_item(scenario_id=scenario["id"], alternative_id=base["id"], rank=1)
+        )
+        scen_alt_2 = self._assert_success(
+            self._db_map.add_scenario_alternative_item(
+                scenario_id=scenario["id"], alternative_id=next_level["id"], rank=2
+            )
+        )
+        self._db_mngr.commit_session("Added data.", self._db_map)
+        db_map_scen_alt_data = {
+            self._db_map: [{"alternative_id_list": [scen_alt_2["alternative_id"]], "id": scenario["id"]}]
+        }
+        db_map_typed_data_to_rm = {self._db_map: {"scenario": set()}}
+        self._db_mngr.error_msg = MagicMock()
+        self._db_mngr.set_scenario_alternatives(db_map_scen_alt_data)
+        self._db_mngr.remove_items(db_map_typed_data_to_rm)
+        self._db_mngr.commit_session("Remove scenario alternative", self._db_map)
+        self._db_mngr.error_msg.emit.assert_not_called()
+
+
 if __name__ == "__main__":
     unittest.main()