text: from django.contrib.contenttypes.models import ContentType
  from django.core.exceptions import FieldError
  from django.db import IntegrityError
  from django.db.models import Q
  from django.test import SimpleTestCase, TestCase
  
  from .models import (
      AllowsNullGFK, Animal, Carrot, Comparison, ConcreteRelatedModel,
      ForConcreteModelModel, ForProxyModelModel, Gecko, ManualPK, Mineral,
      ProxyRelatedModel, Rock, TaggedItem, ValuableRock, ValuableTaggedItem,
      Vegetable,
  )
  
  
  class GenericRelationsTests(TestCase):
      def setUp(self):
          self.lion = Animal.objects.create(
              common_name="Lion", latin_name="Panthera leo")
          self.platypus = Animal.objects.create(
              common_name="Platypus", latin_name="Ornithorhynchus anatinus")
          Vegetable.objects.create(name="Eggplant", is_yucky=True)
          self.bacon = Vegetable.objects.create(name="Bacon", is_yucky=False)
          self.quartz = Mineral.objects.create(name="Quartz", hardness=7)
  
          # Tagging stuff.
          self.bacon.tags.create(tag="fatty")
          self.bacon.tags.create(tag="salty")
          self.lion.tags.create(tag="yellow")
          self.lion.tags.create(tag="hairy")
  
          # Original list of tags:
          self.comp_func = lambda obj: (
              obj.tag, obj.content_type.model_class(), obj.object_id
          )
  
      def test_generic_update_or_create_when_created(self):
          """
          Should be able to use update_or_create from the generic related manager
          to create a tag. Refs #23611.
          """
          count = self.bacon.tags.count()
          tag, created = self.bacon.tags.update_or_create(tag='stinky')
          self.assertTrue(created)
          self.assertEqual(count + 1, self.bacon.tags.count())
  
      def test_generic_update_or_create_when_updated(self):
          """
          Should be able to use update_or_create from the generic related manager
          to update a tag. Refs #23611.
          """
          count = self.bacon.tags.count()
          tag = self.bacon.tags.create(tag='stinky')
          self.assertEqual(count + 1, self.bacon.tags.count())
          tag, created = self.bacon.tags.update_or_create(defaults={'tag': 'juicy'}, id=tag.id)
          self.assertFalse(created)
          self.assertEqual(count + 1, self.bacon.tags.count())
          self.assertEqual(tag.tag, 'juicy')
  
      def test_generic_get_or_create_when_created(self):
          """
          Should be able to use get_or_create from the generic related manager
          to create a tag. Refs #23611.
          """
          count = self.bacon.tags.count()
          tag, created = self.bacon.tags.get_or_create(tag='stinky')
          self.assertTrue(created)
          self.assertEqual(count + 1, self.bacon.tags.count())
  
      def test_generic_get_or_create_when_exists(self):
          """
          Should be able to use get_or_create from the generic related manager
          to get a tag. Refs #23611.
          """
          count = self.bacon.tags.count()
          tag = self.bacon.tags.create(tag="stinky")
          self.assertEqual(count + 1, self.bacon.tags.count())
          tag, created = self.bacon.tags.get_or_create(id=tag.id, defaults={'tag': 'juicy'})
          self.assertFalse(created)
          self.assertEqual(count + 1, self.bacon.tags.count())
          # shouldn't had changed the tag
          self.assertEqual(tag.tag, 'stinky')
  
      def test_generic_relations_m2m_mimic(self):
          """
          Objects with declared GenericRelations can be tagged directly -- the
          API mimics the many-to-many API.
          """
          self.assertQuerysetEqual(self.lion.tags.all(), [
              "<TaggedItem: hairy>",
              "<TaggedItem: yellow>"
          ])
          self.assertQuerysetEqual(self.bacon.tags.all(), [
              "<TaggedItem: fatty>",
              "<TaggedItem: salty>"
          ])
  
      def test_access_content_object(self):
          """
          Test accessing the content object like a foreign key.
          """
          tagged_item = TaggedItem.objects.get(tag="salty")
          self.assertEqual(tagged_item.content_object, self.bacon)
  
      def test_query_content_object(self):
          qs = TaggedItem.objects.filter(
              animal__isnull=False).order_by('animal__common_name', 'tag')
          self.assertQuerysetEqual(
              qs, ["<TaggedItem: hairy>", "<TaggedItem: yellow>"]
          )
  
          mpk = ManualPK.objects.create(id=1)
          mpk.tags.create(tag='mpk')
          qs = TaggedItem.objects.filter(
              Q(animal__isnull=False) | Q(manualpk__id=1)).order_by('tag')
          self.assertQuerysetEqual(
              qs, ["hairy", "mpk", "yellow"], lambda x: x.tag)
  
      def test_exclude_generic_relations(self):
          """
          Test lookups over an object without GenericRelations.
          """
          # Recall that the Mineral class doesn't have an explicit GenericRelation
          # defined. That's OK, because you can create TaggedItems explicitly.
          # However, excluding GenericRelations means your lookups have to be a
          # bit more explicit.
          TaggedItem.objects.create(content_object=self.quartz, tag="shiny")
          TaggedItem.objects.create(content_object=self.quartz, tag="clearish")
  
          ctype = ContentType.objects.get_for_model(self.quartz)
          q = TaggedItem.objects.filter(
              content_type__pk=ctype.id, object_id=self.quartz.id
          )
          self.assertQuerysetEqual(q, [
              "<TaggedItem: clearish>",
              "<TaggedItem: shiny>"
          ])
  
      def test_access_via_content_type(self):
          """
          Test lookups through content type.
          """
          self.lion.delete()
          self.platypus.tags.create(tag="fatty")
  
          ctype = ContentType.objects.get_for_model(self.platypus)
  
          self.assertQuerysetEqual(
              Animal.objects.filter(tags__content_type=ctype),
              ["<Animal: Platypus>"])
  
      def test_set_foreign_key(self):
          """
          You can set a generic foreign key in the way you'd expect.
          """
          tag1 = TaggedItem.objects.create(content_object=self.quartz, tag="shiny")
          tag1.content_object = self.platypus
          tag1.save()
  
          self.assertQuerysetEqual(
              self.platypus.tags.all(),
              ["<TaggedItem: shiny>"])
  
      def test_queries_across_generic_relations(self):
          """
          Queries across generic relations respect the content types. Even though
          there are two TaggedItems with a tag of "fatty", this query only pulls
          out the one with the content type related to Animals.
          """
          self.assertQuerysetEqual(Animal.objects.order_by('common_name'), [
              "<Animal: Lion>",
              "<Animal: Platypus>"
          ])
  
      def test_queries_content_type_restriction(self):
          """
          Create another fatty tagged instance with different PK to ensure there
          is a content type restriction in the generated queries below.
          """
          mpk = ManualPK.objects.create(id=self.lion.pk)
          mpk.tags.create(tag="fatty")
          self.platypus.tags.create(tag="fatty")
  
          self.assertQuerysetEqual(
              Animal.objects.filter(tags__tag='fatty'), ["<Animal: Platypus>"])
          self.assertQuerysetEqual(
              Animal.objects.exclude(tags__tag='fatty'), ["<Animal: Lion>"])
  
      def test_object_deletion_with_generic_relation(self):
          """
          If you delete an object with an explicit Generic relation, the related
          objects are deleted when the source object is deleted.
          """
          self.assertQuerysetEqual(TaggedItem.objects.all(), [
              ('fatty', Vegetable, self.bacon.pk),
              ('hairy', Animal, self.lion.pk),
              ('salty', Vegetable, self.bacon.pk),
              ('yellow', Animal, self.lion.pk)
          ],
              self.comp_func
          )
          self.lion.delete()
  
          self.assertQuerysetEqual(TaggedItem.objects.all(), [
              ('fatty', Vegetable, self.bacon.pk),
              ('salty', Vegetable, self.bacon.pk),
          ],
              self.comp_func
          )
  
      def test_object_deletion_without_generic_relation(self):
          """
          If Generic Relation is not explicitly defined, any related objects
          remain after deletion of the source object.
          """
          TaggedItem.objects.create(content_object=self.quartz, tag="clearish")
          quartz_pk = self.quartz.pk
          self.quartz.delete()
          self.assertQuerysetEqual(TaggedItem.objects.all(), [
              ('clearish', Mineral, quartz_pk),
              ('fatty', Vegetable, self.bacon.pk),
              ('hairy', Animal, self.lion.pk),
              ('salty', Vegetable, self.bacon.pk),
              ('yellow', Animal, self.lion.pk),
          ],
              self.comp_func
          )
  
      def test_tag_deletion_related_objects_unaffected(self):
          """
          If you delete a tag, the objects using the tag are unaffected (other
          than losing a tag).
          """
          ctype = ContentType.objects.get_for_model(self.lion)
          tag = TaggedItem.objects.get(
              content_type__pk=ctype.id, object_id=self.lion.id, tag="hairy")
          tag.delete()
  
          self.assertQuerysetEqual(self.lion.tags.all(), ["<TaggedItem: yellow>"])
          self.assertQuerysetEqual(TaggedItem.objects.all(), [
              ('fatty', Vegetable, self.bacon.pk),
              ('salty', Vegetable, self.bacon.pk),
              ('yellow', Animal, self.lion.pk)
          ],
              self.comp_func
          )
  
      def test_add_bulk(self):
          bacon = Vegetable.objects.create(name="Bacon", is_yucky=False)
          t1 = TaggedItem.objects.create(content_object=self.quartz, tag="shiny")
          t2 = TaggedItem.objects.create(content_object=self.quartz, tag="clearish")
          # One update() query.
          with self.assertNumQueries(1):
              bacon.tags.add(t1, t2)
          self.assertEqual(t1.content_object, bacon)
          self.assertEqual(t2.content_object, bacon)
  
      def test_add_bulk_false(self):
          bacon = Vegetable.objects.create(name="Bacon", is_yucky=False)
          t1 = TaggedItem.objects.create(content_object=self.quartz, tag="shiny")
          t2 = TaggedItem.objects.create(content_object=self.quartz, tag="clearish")
          # One save() for each object.
          with self.assertNumQueries(2):
              bacon.tags.add(t1, t2, bulk=False)
          self.assertEqual(t1.content_object, bacon)
          self.assertEqual(t2.content_object, bacon)
  
      def test_add_rejects_unsaved_objects(self):
          t1 = TaggedItem(content_object=self.quartz, tag="shiny")
          msg = "<TaggedItem: shiny> instance isn't saved. Use bulk=False or save the object first."
          with self.assertRaisesMessage(ValueError, msg):
              self.bacon.tags.add(t1)
  
      def test_add_rejects_wrong_instances(self):
          msg = "'TaggedItem' instance expected, got <Animal: Lion>"
          with self.assertRaisesMessage(TypeError, msg):
              self.bacon.tags.add(self.lion)
  
      def test_set(self):
          bacon = Vegetable.objects.create(name="Bacon", is_yucky=False)
          fatty = bacon.tags.create(tag="fatty")
          salty = bacon.tags.create(tag="salty")
  
          bacon.tags.set([fatty, salty])
          self.assertQuerysetEqual(bacon.tags.all(), [
              "<TaggedItem: fatty>",
              "<TaggedItem: salty>",
          ])
  
          bacon.tags.set([fatty])
          self.assertQuerysetEqual(bacon.tags.all(), [
              "<TaggedItem: fatty>",
          ])
  
          bacon.tags.set([])
          self.assertQuerysetEqual(bacon.tags.all(), [])
  
          bacon.tags.set([fatty, salty], bulk=False, clear=True)
          self.assertQuerysetEqual(bacon.tags.all(), [
              "<TaggedItem: fatty>",
              "<TaggedItem: salty>",
          ])
  
          bacon.tags.set([fatty], bulk=False, clear=True)
          self.assertQuerysetEqual(bacon.tags.all(), [
              "<TaggedItem: fatty>",
          ])
  
          bacon.tags.set([], clear=True)
          self.assertQuerysetEqual(bacon.tags.all(), [])
  
      def test_assign(self):
          bacon = Vegetable.objects.create(name="Bacon", is_yucky=False)
          fatty = bacon.tags.create(tag="fatty")
          salty = bacon.tags.create(tag="salty")
  
          bacon.tags.set([fatty, salty])
          self.assertQuerysetEqual(bacon.tags.all(), [
              "<TaggedItem: fatty>",
              "<TaggedItem: salty>",
          ])
  
          bacon.tags.set([fatty])
          self.assertQuerysetEqual(bacon.tags.all(), [
              "<TaggedItem: fatty>",
          ])
  
          bacon.tags.set([])
          self.assertQuerysetEqual(bacon.tags.all(), [])
  
      def test_assign_with_queryset(self):
          # Querysets used in reverse GFK assignments are pre-evaluated so their
          # value isn't affected by the clearing operation
          # in ManyRelatedManager.set() (#19816).
          bacon = Vegetable.objects.create(name="Bacon", is_yucky=False)
          bacon.tags.create(tag="fatty")
          bacon.tags.create(tag="salty")
          self.assertEqual(2, bacon.tags.count())
  
          qs = bacon.tags.filter(tag="fatty")
          bacon.tags.set(qs)
  
          self.assertEqual(1, bacon.tags.count())
          self.assertEqual(1, qs.count())
  
      def test_generic_relation_related_name_default(self):
          # GenericRelation isn't usable from the reverse side by default.
          msg = (
              "Cannot resolve keyword 'vegetable' into field. Choices are: "
              "animal, content_object, content_type, content_type_id, id, "
              "manualpk, object_id, tag, valuabletaggeditem"
          )
          with self.assertRaisesMessage(FieldError, msg):
              TaggedItem.objects.filter(vegetable__isnull=True)
  
      def test_multiple_gfk(self):
          # Simple tests for multiple GenericForeignKeys
          # only uses one model, since the above tests should be sufficient.
          tiger = Animal.objects.create(common_name="tiger")
          cheetah = Animal.objects.create(common_name="cheetah")
          bear = Animal.objects.create(common_name="bear")
  
          # Create directly
          Comparison.objects.create(
              first_obj=cheetah, other_obj=tiger, comparative="faster"
          )
          Comparison.objects.create(
              first_obj=tiger, other_obj=cheetah, comparative="cooler"
          )
  
          # Create using GenericRelation
          tiger.comparisons.create(other_obj=bear, comparative="cooler")
          tiger.comparisons.create(other_obj=cheetah, comparative="stronger")
          self.assertQuerysetEqual(cheetah.comparisons.all(), [
              "<Comparison: cheetah is faster than tiger>"
          ])
  
          # Filtering works
          self.assertQuerysetEqual(tiger.comparisons.filter(comparative="cooler"), [
              "<Comparison: tiger is cooler than cheetah>",
              "<Comparison: tiger is cooler than bear>",
          ], ordered=False)
  
          # Filtering and deleting works
          subjective = ["cooler"]
          tiger.comparisons.filter(comparative__in=subjective).delete()
          self.assertQuerysetEqual(Comparison.objects.all(), [
              "<Comparison: cheetah is faster than tiger>",
              "<Comparison: tiger is stronger than cheetah>"
          ], ordered=False)
  
          # If we delete cheetah, Comparisons with cheetah as 'first_obj' will be
          # deleted since Animal has an explicit GenericRelation to Comparison
          # through first_obj. Comparisons with cheetah as 'other_obj' will not
          # be deleted.
          cheetah.delete()
          self.assertQuerysetEqual(Comparison.objects.all(), [
              "<Comparison: tiger is stronger than None>"
          ])
  
      def test_gfk_subclasses(self):
          # GenericForeignKey should work with subclasses (see #8309)
          quartz = Mineral.objects.create(name="Quartz", hardness=7)
          valuedtag = ValuableTaggedItem.objects.create(
              content_object=quartz, tag="shiny", value=10
          )
          self.assertEqual(valuedtag.content_object, quartz)
  
      def test_generic_relation_to_inherited_child(self):
          # GenericRelations to models that use multi-table inheritance work.
          granite = ValuableRock.objects.create(name='granite', hardness=5)
          ValuableTaggedItem.objects.create(content_object=granite, tag="countertop", value=1)
          self.assertEqual(ValuableRock.objects.filter(tags__value=1).count(), 1)
          # We're generating a slightly inefficient query for tags__tag - we
          # first join ValuableRock -> TaggedItem -> ValuableTaggedItem, and then
          # we fetch tag by joining TaggedItem from ValuableTaggedItem. The last
          # join isn't necessary, as TaggedItem <-> ValuableTaggedItem is a
          # one-to-one join.
          self.assertEqual(ValuableRock.objects.filter(tags__tag="countertop").count(), 1)
          granite.delete()  # deleting the rock should delete the related tag.
          self.assertEqual(ValuableTaggedItem.objects.count(), 0)
  
      def test_gfk_manager(self):
          # GenericForeignKey should not use the default manager (which may filter objects) #16048
          tailless = Gecko.objects.create(has_tail=False)
          tag = TaggedItem.objects.create(content_object=tailless, tag="lizard")
          self.assertEqual(tag.content_object, tailless)
  
      def test_subclasses_with_gen_rel(self):
          """
          Concrete model subclasses with generic relations work
          correctly (ticket 11263).
          """
          granite = Rock.objects.create(name='granite', hardness=5)
          TaggedItem.objects.create(content_object=granite, tag="countertop")
          self.assertEqual(Rock.objects.get(tags__tag="countertop"), granite)
  
      def test_subclasses_with_parent_gen_rel(self):
          """
          Generic relations on a base class (Vegetable) work correctly in
          subclasses (Carrot).
          """
          bear = Carrot.objects.create(name='carrot')
          TaggedItem.objects.create(content_object=bear, tag='orange')
          self.assertEqual(Carrot.objects.get(tags__tag='orange'), bear)
  
      def test_get_or_create(self):
          # get_or_create should work with virtual fields (content_object)
          quartz = Mineral.objects.create(name="Quartz", hardness=7)
          tag, created = TaggedItem.objects.get_or_create(tag="shiny", defaults={'content_object': quartz})
          self.assertTrue(created)
          self.assertEqual(tag.tag, "shiny")
          self.assertEqual(tag.content_object.id, quartz.id)
  
      def test_update_or_create_defaults(self):
          # update_or_create should work with virtual fields (content_object)
          quartz = Mineral.objects.create(name="Quartz", hardness=7)
          diamond = Mineral.objects.create(name="Diamond", hardness=7)
          tag, created = TaggedItem.objects.update_or_create(tag="shiny", defaults={'content_object': quartz})
          self.assertTrue(created)
          self.assertEqual(tag.content_object.id, quartz.id)
  
          tag, created = TaggedItem.objects.update_or_create(tag="shiny", defaults={'content_object': diamond})
          self.assertFalse(created)
          self.assertEqual(tag.content_object.id, diamond.id)
  
      def test_query_content_type(self):
          msg = "Field 'content_object' does not generate an automatic reverse relation"
          with self.assertRaisesMessage(FieldError, msg):
              TaggedItem.objects.get(content_object='')
  
      def test_unsaved_instance_on_generic_foreign_key(self):
          """
          Assigning an unsaved object to GenericForeignKey should raise an
          exception on model.save().
          """
          quartz = Mineral(name="Quartz", hardness=7)
          with self.assertRaises(IntegrityError):
              TaggedItem.objects.create(tag="shiny", content_object=quartz)
  
      def test_cache_invalidation_for_content_type_id(self):
          # Create a Vegetable and Mineral with the same id.
          new_id = max(Vegetable.objects.order_by('-id')[0].id,
                       Mineral.objects.order_by('-id')[0].id) + 1
          broccoli = Vegetable.objects.create(id=new_id, name="Broccoli")
          diamond = Mineral.objects.create(id=new_id, name="Diamond", hardness=7)
          tag = TaggedItem.objects.create(content_object=broccoli, tag="yummy")
          tag.content_type = ContentType.objects.get_for_model(diamond)
          self.assertEqual(tag.content_object, diamond)
  
      def test_cache_invalidation_for_object_id(self):
          broccoli = Vegetable.objects.create(name="Broccoli")
          cauliflower = Vegetable.objects.create(name="Cauliflower")
          tag = TaggedItem.objects.create(content_object=broccoli, tag="yummy")
          tag.object_id = cauliflower.id
          self.assertEqual(tag.content_object, cauliflower)
  
      def test_assign_content_object_in_init(self):
          spinach = Vegetable(name="spinach")
          tag = TaggedItem(content_object=spinach)
          self.assertEqual(tag.content_object, spinach)
  
      def test_create_after_prefetch(self):
          platypus = Animal.objects.prefetch_related('tags').get(pk=self.platypus.pk)
          self.assertSequenceEqual(platypus.tags.all(), [])
          weird_tag = platypus.tags.create(tag='weird')
          self.assertSequenceEqual(platypus.tags.all(), [weird_tag])
  
      def test_add_after_prefetch(self):
          platypus = Animal.objects.prefetch_related('tags').get(pk=self.platypus.pk)
          self.assertSequenceEqual(platypus.tags.all(), [])
          weird_tag = TaggedItem.objects.create(tag='weird', content_object=platypus)
          platypus.tags.add(weird_tag)
          self.assertSequenceEqual(platypus.tags.all(), [weird_tag])
  
      def test_remove_after_prefetch(self):
          weird_tag = self.platypus.tags.create(tag='weird')
          platypus = Animal.objects.prefetch_related('tags').get(pk=self.platypus.pk)
          self.assertSequenceEqual(platypus.tags.all(), [weird_tag])
          platypus.tags.remove(weird_tag)
          self.assertSequenceEqual(platypus.tags.all(), [])
  
      def test_clear_after_prefetch(self):
          weird_tag = self.platypus.tags.create(tag='weird')
          platypus = Animal.objects.prefetch_related('tags').get(pk=self.platypus.pk)
          self.assertSequenceEqual(platypus.tags.all(), [weird_tag])
          platypus.tags.clear()
          self.assertSequenceEqual(platypus.tags.all(), [])
  
      def test_set_after_prefetch(self):
          platypus = Animal.objects.prefetch_related('tags').get(pk=self.platypus.pk)
          self.assertSequenceEqual(platypus.tags.all(), [])
          furry_tag = TaggedItem.objects.create(tag='furry', content_object=platypus)
          platypus.tags.set([furry_tag])
          self.assertSequenceEqual(platypus.tags.all(), [furry_tag])
          weird_tag = TaggedItem.objects.create(tag='weird', content_object=platypus)
          platypus.tags.set([weird_tag])
          self.assertSequenceEqual(platypus.tags.all(), [weird_tag])
  
      def test_add_then_remove_after_prefetch(self):
          furry_tag = self.platypus.tags.create(tag='furry')
          platypus = Animal.objects.prefetch_related('tags').get(pk=self.platypus.pk)
          self.assertSequenceEqual(platypus.tags.all(), [furry_tag])
          weird_tag = self.platypus.tags.create(tag='weird')
          platypus.tags.add(weird_tag)
          self.assertSequenceEqual(platypus.tags.all(), [furry_tag, weird_tag])
          platypus.tags.remove(weird_tag)
          self.assertSequenceEqual(platypus.tags.all(), [furry_tag])
  
  
  class ProxyRelatedModelTest(TestCase):
      def test_default_behavior(self):
          """
          The default for for_concrete_model should be True
          """
          base = ForConcreteModelModel()
          base.obj = rel = ProxyRelatedModel.objects.create()
          base.save()
  
          base = ForConcreteModelModel.objects.get(pk=base.pk)
          rel = ConcreteRelatedModel.objects.get(pk=rel.pk)
          self.assertEqual(base.obj, rel)
  
      def test_works_normally(self):
          """
          When for_concrete_model is False, we should still be able to get
          an instance of the concrete class.
          """
          base = ForProxyModelModel()
          base.obj = rel = ConcreteRelatedModel.objects.create()
          base.save()
  
          base = ForProxyModelModel.objects.get(pk=base.pk)
          self.assertEqual(base.obj, rel)
  
      def test_proxy_is_returned(self):
          """
          Instances of the proxy should be returned when
          for_concrete_model is False.
          """
          base = ForProxyModelModel()
          base.obj = ProxyRelatedModel.objects.create()
          base.save()
  
          base = ForProxyModelModel.objects.get(pk=base.pk)
          self.assertIsInstance(base.obj, ProxyRelatedModel)
  
      def test_query(self):
          base = ForProxyModelModel()
          base.obj = rel = ConcreteRelatedModel.objects.create()
          base.save()
  
          self.assertEqual(rel, ConcreteRelatedModel.objects.get(bases__id=base.id))
  
      def test_query_proxy(self):
          base = ForProxyModelModel()
          base.obj = rel = ProxyRelatedModel.objects.create()
          base.save()
  
          self.assertEqual(rel, ProxyRelatedModel.objects.get(bases__id=base.id))
  
      def test_generic_relation(self):
          base = ForProxyModelModel()
          base.obj = ProxyRelatedModel.objects.create()
          base.save()
  
          base = ForProxyModelModel.objects.get(pk=base.pk)
          rel = ProxyRelatedModel.objects.get(pk=base.obj.pk)
          self.assertEqual(base, rel.bases.get())
  
      def test_generic_relation_set(self):
          base = ForProxyModelModel()
          base.obj = ConcreteRelatedModel.objects.create()
          base.save()
          newrel = ConcreteRelatedModel.objects.create()
  
          newrel.bases.set([base])
          newrel = ConcreteRelatedModel.objects.get(pk=newrel.pk)
          self.assertEqual(base, newrel.bases.get())
  
  
  class TestInitWithNoneArgument(SimpleTestCase):
  
      def test_none_allowed(self):
          # AllowsNullGFK doesn't require a content_type, so None argument should
          # also be allowed.
          AllowsNullGFK(content_object=None)
          # TaggedItem requires a content_type but initializing with None should
          # be allowed.
          TaggedItem(content_object=None)
  