Update membership upgrade discount conditions to match HR (#3641)

A user now gets the discount also in the year after last having been a member.

website/registrations/forms.py

@@ -1,3 +1,5 @@
+from datetime import timedelta
+
 from django import forms
 from django.conf import settings
 from django.core.exceptions import NON_FIELD_ERRORS, ValidationError
@@ -223,7 +225,7 @@ def clean(self):
             if Membership.objects.filter(
                 user=self.cleaned_data["member"],
                 type=Membership.MEMBER,
-                until__gte=now,
+                until__gte=now - timedelta(days=366),
                 since__lte=now,
             ).exists():
                 # The membership upgrade discount applies if, at the time a Renewal is

website/registrations/tests/test_forms.py

@@ -177,6 +177,21 @@ def test_price_calculation(self):
                 )
                 renewal.delete()
 
+        with self.subTest("Member, membership upgrade discount (last year)"):
+            with freeze_time("2024-10-20"):
+                # The user had a membership last year, but still should get a discount.
+                self.data["length"] = Entry.MEMBERSHIP_STUDY
+                self.data["membership_type"] = Membership.MEMBER
+                form = forms.RenewalForm(self.data)
+                self.assertTrue(form.is_valid())
+                renewal = form.save()
+                self.assertEqual(
+                    renewal.contribution,
+                    settings.MEMBERSHIP_PRICES[Entry.MEMBERSHIP_STUDY]
+                    - settings.MEMBERSHIP_PRICES[Entry.MEMBERSHIP_YEAR],
+                )
+                renewal.delete()
+
         with self.subTest("Member, new year membership before expiry"):
             with freeze_time("2024-08-20"):
                 self.data["length"] = Entry.MEMBERSHIP_YEAR
@@ -203,8 +218,9 @@ def test_price_calculation(self):
                 )
                 renewal.delete()
 
-        with self.subTest("Member, study membership after expiry"):
-            with freeze_time("2024-09-10"):
+        with self.subTest("Member, study membership after more than a year"):
+            with freeze_time("2025-09-10"):
+                # The membership discount applies up to 1 year after the user last had a membership.
                 self.data["length"] = Entry.MEMBERSHIP_STUDY
                 self.data["membership_type"] = Membership.MEMBER
                 form = forms.RenewalForm(self.data)