feat(appsettings): the Settings page groups its settings and saves a group at once

The page listed 37 settings by name, each its own form saved as soon as
its list or field changed, with the description only in a tooltip. It
now shows them in groups (New VM defaults, Disks, Clones, Console, VM
access and owners, Snapshots and jobs, Login, Lists and pages) with each
description under its field and the label tied to it. A group's Save
button saves its changed settings, or none when one is refused, and
says which were saved; number settings are number fields with their
range. Language and theme are under Appearance with their own buttons.
A setting in no group shows under Other.

appsettings/tests/test_appsettings.py

@@ -83,3 +83,45 @@ class AppSettingsTestCase(TestCase):
         page = self.client.get(reverse("appsettings")).content.decode()
         self.assertIn('name="CLONE_INSTANCE_DEFAULT_PREFIX" value="web-"', page)
 
+    def page(self):
+        from lxml import html
+
+        return html.fromstring(self.client.get(reverse("appsettings")).content)
+
+    def test_settings_are_grouped_with_their_descriptions_shown(self):
+        page = self.page()
+        titles = [h.text_content().strip() for h in page.xpath("//form//h2")]
+        self.assertEqual(titles[:3], ["New VM defaults", "Disks", "Clones"])
+        # every setting is in one group, with a label tied to its field and its description shown
+        keys = page.xpath("//form//*[self::input or self::select][@name and @name!='csrfmiddlewaretoken']/@name")
+        names = set(AppSettings.objects.exclude(key="BOOTSTRAP_THEME").values_list("key", flat=True))
+        self.assertEqual(sorted(k for k in keys if k not in ("BOOTSTRAP_THEME", "language")), sorted(names))
+        (field,) = page.xpath("//*[@name='LOGS_PER_PAGE']")
+        self.assertEqual((field.get("type"), field.get("min"), field.get("max")), ("number", "1", "1000"))
+        self.assertEqual(page.xpath(f"//label[@for='{field.get('id')}']/text()"), ["Logs per Page"])
+        self.assertEqual(page.xpath(f"//*[@id='{field.get('aria-describedby')}']/text()"), ["Pagination for logs"])
+        # a group is saved with its button, not on every change
+        self.assertEqual(page.xpath("//*[@onchange]"), [])
+
+    def test_a_group_saves_its_changed_settings_only(self):
+        from logs.models import Logs
+
+        Logs.objects.all().delete()
+        response = self.client.post(reverse("appsettings"), {
+            "CONSOLE_SCALE": "True", "CONSOLE_VIEW_ONLY": "False",
+            "CONSOLE_RESIZE_SESSION": "False", "CONSOLE_CLIP_VIEWPORT": "True"})
+        self.assertRedirects(response, reverse("appsettings"))
+        values = dict(AppSettings.objects.filter(key__startswith="CONSOLE_").values_list("key", "value"))
+        self.assertEqual(values, {"CONSOLE_SCALE": "True", "CONSOLE_VIEW_ONLY": "False",
+                                  "CONSOLE_RESIZE_SESSION": "False", "CONSOLE_CLIP_VIEWPORT": "True"})
+        self.assertEqual(sorted(Logs.objects.values_list("message", flat=True)),
+                         ["Setting Console Clip Viewport: change to True", "Setting Console Scale: change to True"])
+        self.assertEqual([str(m) for m in get_messages(response.wsgi_request)],
+                         ["Saved: Console Clip Viewport, Console Scale"])
+
+    def test_one_bad_value_saves_nothing_of_its_group(self):
+        response = self.client.post(reverse("appsettings"), {"LOGIN_FAILURE_LIMIT": "10", "LOGIN_LOCKOUT_MINUTES": "x"})
+        self.assertEqual(AppSettings.objects.get(key="LOGIN_FAILURE_LIMIT").value, "5")
+        self.assertEqual([str(m) for m in get_messages(response.wsgi_request)],
+                         ["Login Lockout Minutes must be a whole number between 1 and 10080"])
+