chore(appsettings): one squashed migration for a new database

0001_initial to 0024_log_retention_setting are mostly RunPython steps
that added, renamed, re-chose and described setting rows since 2020. A
squashed migration now creates the table in its final shape and inserts
the 38 rows those steps leave; it replaces all 24, so a new database
runs it alone. The 24 stay beside it, as Django's squashing expects
until every installation has applied them: a database that applied
them all records the squashed one without running anything, and one
that stopped between them (an older release, or an upstream
installation) applies the rest of them first.

Checked:
- on a new database its rows equal the old chain's (name, key, value,
  choices, description of every row);
- on a copy of a running panel's database (all 24 applied) migrate
  plans nothing for appsettings;
- a database migrated by the old code to 0023 applies 0024 and then
  records the squashed migration, with the same 38 rows;
- makemigrations finds no change.

It inserts its rows on the database being migrated, as the replaced steps
do. The tests of the replaced steps stay, since an installation that stopped
between them still runs them; the two that checked a few rows' columns
became one that checks every row's columns and description, and a value is
one of its choices.

appsettings/tests/test_migrations.py

@@ -1,6 +1,8 @@
-"""The default settings rows of the first migrations carry fixed ids, which a
-PostgreSQL id sequence does not see. A later migration that inserts without
-an id must not collide with them."""
+"""The settings rows: those a new database gets fit their columns (PostgreSQL
+refuses a longer value, SQLite does not), say what they do, and hold one of
+their choices. The steps the squashed migration replaces still run on an
+installation that stopped between them: they repair its rows, and their
+inserts do not collide with the fixed ids of the first ones."""
 
 import importlib
 import unittest
@@ -42,27 +44,6 @@ class NicTypeTestCase(TestCase):
         self.assertEqual((setting.value, setting.choices), ("rtl8139", "default,e1000,e1000e,rtl8139,virtio"))
 
 
-class SnapshotFreeSpaceSettingsTestCase(TestCase):
-    def test_the_rows_fit_their_columns(self):
-        # PostgreSQL refuses a value longer than the column, sqlite does not
-        for key in ("SNAPSHOT_FREE_SPACE_PERCENT", "SNAPSHOT_FREE_SPACE_MIN_GIB"):
-            setting = AppSettings.objects.get(key=key)
-            for field in ("name", "key", "value", "description"):
-                limit = AppSettings._meta.get_field(field).max_length
-                if limit:
-                    self.assertLessEqual(len(getattr(setting, field)), limit, f"{key} {field}")
-
-
-class WorkerSettingsTestCase(TestCase):
-    def test_the_rows_fit_their_columns(self):
-        for key in ("WORKER_CONCURRENCY", "JOB_RETENTION_DAYS", "LOG_RETENTION_DAYS"):
-            setting = AppSettings.objects.get(key=key)
-            for field in ("name", "key", "value", "description"):
-                limit = AppSettings._meta.get_field(field).max_length
-                if limit:
-                    self.assertLessEqual(len(getattr(setting, field)), limit, f"{key} {field}")
-
-
 choices_fix = importlib.import_module("appsettings.migrations.0020_fix_setting_choices")
 
 
@@ -116,3 +97,26 @@ class CpuModeChoicesTestCase(TestCase):
                 cpu_mode.fix_cpu_mode(apps, SimpleNamespace(connection=connection))
                 setting = AppSettings.objects.get(key="INSTANCE_CPU_DEFAULT_MODE")
                 self.assertEqual((setting.value, setting.choices), (new, "host-model,host-passthrough,maximum"))
+
+
+class SettingsRowsTestCase(TestCase):
+    def test_every_row_fits_its_columns_and_has_a_description(self):
+        for setting in AppSettings.objects.all():
+            with self.subTest(key=setting.key):
+                self.assertTrue(setting.description)
+                for field in ("name", "key", "value", "choices", "description"):
+                    limit = AppSettings._meta.get_field(field).max_length
+                    self.assertLessEqual(len(getattr(setting, field)), limit, field)
+
+    def test_a_setting_with_choices_holds_one_of_them(self):
+        for setting in AppSettings.objects.exclude(choices=""):
+            with self.subTest(key=setting.key):
+                self.assertIn(setting.value, setting.choices_as_list())
+
+    def test_the_choices_offer_only_what_the_panel_uses(self):
+        rows = {s.key: (s.value, s.choices) for s in AppSettings.objects.all()}
+        self.assertEqual(rows["INSTANCE_NIC_DEFAULT_TYPE"][1], "default,e1000,e1000e,rtl8139,virtio")
+        self.assertEqual(rows["INSTANCE_CPU_DEFAULT_MODE"], ("host-model", "host-model,host-passthrough,maximum"))
+        self.assertEqual(rows["INSTANCE_MACHINE_DEFAULT_TYPE"], ("q35", "q35,pc,virt"))
+        self.assertEqual(rows["INSTANCE_CDROM_ADD"], ("sata", "None,ide,sata,scsi"))
+        self.assertEqual(rows["CLONE_INSTANCE_DEFAULT_PREFIX"][1], "")