Fix quota cache mixup (#3539)

Co-authored-by: Richard Schreiber <schreiber@rami.io>

src/tests/base/test_models.py

@@ -98,6 +98,7 @@ class BaseQuotaTestCase(TestCase):
         self.var3 = ItemVariation.objects.create(item=self.item3, value='Fancy')
 
 
+@pytest.mark.usefixtures("fakeredis_client")
 class QuotaTestCase(BaseQuotaTestCase):
     @classscope(attr='o')
     def test_available(self):
@@ -434,6 +435,62 @@ class QuotaTestCase(BaseQuotaTestCase):
         self.assertEqual(self.var1.check_quotas(), (Quota.AVAILABILITY_ORDERED, 0))
         self.assertEqual(self.var1.check_quotas(count_waitinglist=False), (Quota.AVAILABILITY_OK, 1))
 
+    @classscope(attr='o')
+    def test_waitinglist_cache_separation(self):
+        self.quota.items.add(self.item1)
+        self.quota.size = 1
+        self.quota.save()
+        WaitingListEntry.objects.create(
+            event=self.event, item=self.item1, email='foo@bar.com'
+        )
+
+        # Check that there is no "cache mixup" even across multiple runs
+        qa = QuotaAvailability(count_waitinglist=False)
+        qa.queue(self.quota)
+        qa.compute()
+        assert qa.results[self.quota] == (Quota.AVAILABILITY_OK, 1)
+
+        qa = QuotaAvailability(count_waitinglist=True)
+        qa.queue(self.quota)
+        qa.compute(allow_cache=True)
+        assert qa.results[self.quota] == (Quota.AVAILABILITY_ORDERED, 0)
+
+        qa = QuotaAvailability(count_waitinglist=True)
+        qa.queue(self.quota)
+        qa.compute(allow_cache=True)
+        assert qa.results[self.quota] == (Quota.AVAILABILITY_ORDERED, 0)
+
+        qa = QuotaAvailability(count_waitinglist=False)
+        qa.queue(self.quota)
+        qa.compute()
+        assert qa.results[self.quota] == (Quota.AVAILABILITY_OK, 1)
+
+        # Rebuild cache required
+        self.quota.size = 5
+        self.quota.save()
+
+        qa = QuotaAvailability(count_waitinglist=True)
+        qa.queue(self.quota)
+        qa.compute(allow_cache=True)
+        assert qa.results[self.quota] == (Quota.AVAILABILITY_ORDERED, 0)
+
+        qa = QuotaAvailability(count_waitinglist=False)
+        qa.queue(self.quota)
+        qa.compute(allow_cache=True)
+        assert qa.results[self.quota] == (Quota.AVAILABILITY_OK, 1)
+
+        self.quota.rebuild_cache()
+
+        qa = QuotaAvailability(count_waitinglist=True)
+        qa.queue(self.quota)
+        qa.compute(allow_cache=True)
+        assert qa.results[self.quota] == (Quota.AVAILABILITY_OK, 4)
+
+        qa = QuotaAvailability(count_waitinglist=False)
+        qa.queue(self.quota)
+        qa.compute(allow_cache=True)
+        assert qa.results[self.quota] == (Quota.AVAILABILITY_OK, 5)
+
     @classscope(attr='o')
     def test_waitinglist_variation_fulfilled(self):
         self.quota.variations.add(self.var1)

src/tests/conftest.py

@@ -22,10 +22,14 @@
 import inspect
 
 import pytest
+from django.test import override_settings
 from django.utils import translation
 from django_scopes import scopes_disabled
+from fakeredis import FakeConnection
 from xdist.dsession import DSession
 
+from pretix.testutils.mock import get_redis_connection
+
 CRASHED_ITEMS = set()
 
 
@@ -74,3 +78,38 @@ def pytest_fixture_setup(fixturedef, request):
 @pytest.fixture(autouse=True)
 def reset_locale():
     translation.activate("en")
+
+
+@pytest.fixture
+def fakeredis_client(monkeypatch):
+    with override_settings(
+        HAS_REDIS=True,
+        REAL_CACHE_USED=True,
+        CACHES={
+            'redis': {
+                'BACKEND': 'django.core.cache.backends.redis.RedisCache',
+                'LOCATION': 'redis://127.0.0.1',
+                'OPTIONS': {
+                    'connection_class': FakeConnection
+                }
+            },
+            'redis_session': {
+                'BACKEND': 'django.core.cache.backends.redis.RedisCache',
+                'LOCATION': 'redis://127.0.0.1',
+                'OPTIONS': {
+                    'connection_class': FakeConnection
+                }
+            },
+            'default': {
+                'BACKEND': 'django.core.cache.backends.redis.RedisCache',
+                'LOCATION': 'redis://127.0.0.1',
+                'OPTIONS': {
+                    'connection_class': FakeConnection
+                }
+            },
+        }
+    ):
+        redis = get_redis_connection("default", True)
+        redis.flushall()
+        monkeypatch.setattr('django_redis.get_redis_connection', get_redis_connection, raising=False)
+        yield redis