Fall back to the basic role when somebody holds no office

FusionIIIT/applications/globals/decorators.py

@@ -32,12 +32,16 @@ def active_designation(user):
     office outranks the basic role, which is the rule the IAM applies too — so
     somebody who has never touched the role switcher is not locked out of the
     post they hold.
+
+    Falling through to the basic role matters: most people hold nothing else,
+    and treating "no office" as "no role" refuses every student their own
+    screens.
     """
     held = held_designations(user)
     chosen = getattr(getattr(user, 'extrainfo', None), 'last_selected_role', None)
     if chosen and chosen.lower() in held:
         return chosen.lower()
-    return next(iter(sorted(held - BASIC_ROLES)), None)
+    return next(iter(sorted(held - BASIC_ROLES)), None) or next(iter(sorted(held)), None)
 
 
 def role_required(allowed_roles):

FusionIIIT/applications/globals/tests.py

@@ -98,11 +98,11 @@ def test_never_having_switched_does_not_lock_the_office_out(self):
         """The column is null for anyone who has not used the switcher."""
         self.assertEqual(active_designation(self.user), 'acadadmin')
 
-    def test_a_role_that_is_no_longer_held_is_ignored(self):
+    def test_a_role_that_is_no_longer_held_falls_back_to_one_that_is(self):
         self._act_as('acadadmin')
         HoldsDesignation.objects.filter(
             designation__name='acadadmin').delete()
-        self.assertIsNone(active_designation(self.user))
+        self.assertEqual(active_designation(self.user), 'student')
 
     def test_a_stand_in_is_authorised_and_the_absent_holder_is_not(self):
         """`working` is the occupant; `user` is the substantive holder."""
@@ -151,3 +151,21 @@ def test_an_old_token_is_refused_and_destroyed(self):
         with self.assertRaises(AuthenticationFailed):
             self.auth.authenticate_credentials(self.token.key)
         self.assertFalse(Token.objects.filter(pk=self.token.pk).exists())
+
+
+class PlainStudentTests(TestCase):
+    """Most people hold no office at all. They must keep their own screens."""
+
+    def setUp(self):
+        self.user = User.objects.create_user(username='student1')
+        ExtraInfo.objects.create(id='student1', user=self.user, user_type='student')
+        HoldsDesignation.objects.create(
+            user=self.user, working=self.user,
+            designation=Designation.objects.create(name='student'))
+
+    def test_a_student_holding_only_the_basic_role_still_acts_in_it(self):
+        self.assertEqual(active_designation(self.user), 'student')
+
+    def test_somebody_holding_nothing_acts_in_nothing(self):
+        bare = User.objects.create_user(username='nobody')
+        self.assertIsNone(active_designation(bare))