Better cache eviction and testing (#635)

guardian/__init__.py

@@ -18,7 +18,7 @@ def get_version():
 
 def monkey_patch_user():
     from django.contrib.auth import get_user_model
-    from .utils import get_anonymous_user
+    from .utils import get_anonymous_user, evict_obj_perms_cache
     from .models import UserObjectPermission
     User = get_user_model()
     # Prototype User and Group methods
@@ -27,4 +27,4 @@ def monkey_patch_user():
             lambda self, perm, obj: UserObjectPermission.objects.assign_perm(perm, self, obj))
     setattr(User, 'del_obj_perm',
             lambda self, perm, obj: UserObjectPermission.objects.remove_perm(perm, self, obj))
-    setattr(User, 'evict_obj_perm_cache', lambda self: delattr(self, '_guardian_perms_cache'))
+    setattr(User, 'evict_obj_perms_cache', evict_obj_perms_cache)

guardian/testapp/tests/test_core.py

@@ -14,6 +14,7 @@
 from guardian.models import UserObjectPermission, GroupObjectPermission
 from guardian.shortcuts import assign_perm
 from guardian.management import create_anonymous_user
+from guardian.utils import evict_obj_perms_cache
 
 from guardian.testapp.models import Project, ProjectUserObjectPermission, ProjectGroupObjectPermission
 
@@ -457,6 +458,13 @@ def test_autoprefetch_user_perms(self):
             assign_groups = [self.group, group1]
             for group in assign_groups:
                 assign_perm("change_group", user, group)
+
+            # Faux monkeypatching
+            setattr(User, 'evict_obj_perms_cache', evict_obj_perms_cache)
+
+            # Try to evict non-existent cache, should return false
+            self.assertFalse(user.evict_obj_perms_cache())
+
             checker = ObjectPermissionChecker(user)
 
             pre_query_count = len(connection.queries)
@@ -494,6 +502,19 @@ def test_autoprefetch_user_perms(self):
             #  not hit DB
             self.assertFalse(checker.has_perm("change_group", group2))
             self.assertEqual(len(connection.queries), query_count)
+
+            # Evict cache and verify that reloaded perms have changed
+            self.assertTrue(user.evict_obj_perms_cache())
+            self.assertFalse(hasattr(user, '_guardian_perms_cache'))
+            assign_perm("delete_group", user, self.group)
+            query_count = len(connection.queries)
+            # New checker object so that we reload perms from db
+            checker = ObjectPermissionChecker(user)
+            self.assertTrue(checker.has_perm("delete_group", self.group))
+            # Two more queries should have been executed
+            self.assertEqual(len(connection.queries), query_count + 2)
+
+
         finally:
             settings.DEBUG = False
             guardian_settings.AUTO_PREFETCH = False

guardian/testapp/tests/test_other.py

@@ -286,10 +286,15 @@ class CustomUserTestClass(AbstractUser):
         self.assertFalse(getattr(CustomUserTestClass, 'get_anonymous', False))
         self.assertFalse(getattr(CustomUserTestClass, 'add_obj_perm', False))
         self.assertFalse(getattr(CustomUserTestClass, 'del_obj_perm', False))
+        self.assertFalse(getattr(CustomUserTestClass, 'evict_obj_perms_cache', False))
 
         # Monkey Patch
         guardian.monkey_patch_user()
 
         self.assertTrue(getattr(CustomUserTestClass, 'get_anonymous', False))
         self.assertTrue(getattr(CustomUserTestClass, 'add_obj_perm', False))
         self.assertTrue(getattr(CustomUserTestClass, 'del_obj_perm', False))
+        self.assertTrue(getattr(CustomUserTestClass, 'evict_obj_perms_cache', False))
+
+        user = CustomUserTestClass()
+        self.assertFalse(user.evict_obj_perms_cache())

guardian/utils.py

@@ -196,3 +196,10 @@ def get_group_obj_perms_model(obj):
     from guardian.models import GroupObjectPermissionBase
     from guardian.models import GroupObjectPermission
     return get_obj_perms_model(obj, GroupObjectPermissionBase, GroupObjectPermission)
+
+
+def evict_obj_perms_cache(obj):
+    if hasattr(obj, '_guardian_perms_cache'):
+        delattr(obj, '_guardian_perms_cache')
+        return True
+    return False