          # everything else is as expected.
          queryset = OneToOneTarget.objects.all()
          serializer = OneToOneTargetSerializer(queryset)
          expected = [
              {'id': 1, 'name': 'target-1', 'target_source': {'id': 1, 'name': 'target-source-1', 'source': {'id': 1, 'name': 'source-1'}}},
              {'id': 2, 'name': 'target-2', 'target_source': {'id': 2, 'name': 'target-source-2', 'source': {'id': 2, 'name': 'source-2'}}},
              {'id': 3, 'name': 'target-3', 'target_source': {'id': 3, 'name': 'target-source-3', 'source': {'id': 3, 'name': 'source-3'}}},
              {'id': 4, 'name': 'target-4', 'target_source': {'id': 4, 'name': 'target-source-4', 'source': {'id': 4, 'name': 'source-4'}}}
          ]
          self.assertEqual(serializer.data, expected)
  
      def test_one_to_one_create_with_invalid_data(self):
          data = {'id': 4, 'name': 'target-4', 'target_source': {'id': 4, 'name': 'target-source-4', 'source': {'id': 4}}}
 
</s> remove         serializer = OneToOneTargetSerializer(queryset)
 </s> add         serializer = self.Serializer(queryset) </s> remove             {'id': 1, 'name': 'target-1', 'target_source': {'id': 1, 'name': 'target-source-1', 'source': {'id': 1, 'name': 'source-1'}}},
            {'id': 2, 'name': 'target-2', 'target_source': {'id': 2, 'name': 'target-source-2', 'source': {'id': 2, 'name': 'source-2'}}},
            {'id': 3, 'name': 'target-3', 'target_source': {'id': 3, 'name': 'target-source-3', 'source': {'id': 3, 'name': 'source-3'}}}
 </s> add             {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
            {'id': 3, 'name': 'target-3', 'source': {'id': 3, 'name': 'source-3'}} </s> remove         data = {'id': 4, 'name': 'target-4', 'target_source': {'id': 4, 'name': 'target-source-4', 'source': {'id': 4, 'name': 'source-4'}}}
        serializer = OneToOneTargetSerializer(data=data)
 </s> add         data = {'id': 4, 'name': 'target-4', 'source': {'id': 4, 'name': 'source-4'}}
        serializer = self.Serializer(data=data) </s> remove         data = {'id': 4, 'name': 'target-4', 'target_source': {'id': 4, 'name': 'target-source-4', 'source': {'id': 4}}}
        serializer = OneToOneTargetSerializer(data=data)
 </s> add         data = {'id': 4, 'name': 'target-4', 'source': {'id': 4}}
        serializer = self.Serializer(data=data) </s> remove         serializer.save()
 </s> add         obj = serializer.save()
        self.assertEqual(serializer.data, data)
        self.assertEqual(obj.name, 'source-4')

        # Ensure (target 4, target_source 4, source 4) are added, and
        # everything else is as expected.
        queryset = OneToOneSource.objects.all()
        serializer = self.Serializer(queryset)
        expected = [
            {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
            {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
            {'id': 3, 'name': 'source-3', 'target': {'id': 3, 'name': 'target-3'}},
            {'id': 4, 'name': 'source-4', 'target': {'id': 4, 'name': 'target-4'}}
        ]
        self.assertEqual(serializer.data, expected)
            {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
            {'id': 3, 'name': 'target-3', 'source': {'id': 3, 'name': 'source-3'}},
            {'id': 4, 'name': 'target-4', 'source': {'id': 4, 'name': 'source-4'}}
          # everything else is as expected.
          queryset = OneToOneTarget.objects.all()
          serializer = OneToOneTargetSerializer(queryset)
          expected = [
            {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
            {'id': 3, 'name': 'target-3', 'source': {'id': 3, 'name': 'source-3'}},
            {'id': 4, 'name': 'target-4', 'source': {'id': 4, 'name': 'source-4'}}
            {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
            {'id': 3, 'name': 'target-3', 'source': {'id': 3, 'name': 'source-3'}},
            {'id': 4, 'name': 'target-4', 'source': {'id': 4, 'name': 'source-4'}}
            {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
            {'id': 3, 'name': 'target-3', 'source': {'id': 3, 'name': 'source-3'}},
            {'id': 4, 'name': 'target-4', 'source': {'id': 4, 'name': 'source-4'}}
            {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
            {'id': 3, 'name': 'target-3', 'source': {'id': 3, 'name': 'source-3'}},
            {'id': 4, 'name': 'target-4', 'source': {'id': 4, 'name': 'source-4'}}
          ]
          self.assertEqual(serializer.data, expected)
  
      def test_one_to_one_create_with_invalid_data(self):
          data = {'id': 4, 'name': 'target-4', 'target_source': {'id': 4, 'name': 'target-source-4', 'source': {'id': 4}}}
keep keep keep keep replace replace replace replace keep keep keep keep keep
 Cleanup one-one nested tests and implementation 
rest_framework/tests/relations_nested.py