          obj = serializer.save()
          self.assertEquals(serializer.data, data)
          self.assertEqual(obj.name, u'source-4')
  
          # Ensure source 1 is updated, and everything else is as expected
          queryset = ForeignKeySource.objects.all()
          serializer = ForeignKeySourceSerializer(queryset)
          expected = [
              {'id': 1, 'name': u'source-1', 'target': 1},
              {'id': 2, 'name': u'source-2', 'target': 1},
 
</s> remove         # Ensure target 4 is added, and everything else is as expected
 </s> add         # Ensure target 3 is added, and everything else is as expected </s> remove         self.assertEquals(serializer.data, data)
 </s> add  </s> remove         self.assertEquals(serializer.data, data)
 </s> add  </s> remove         self.assertEquals(serializer.data, data)
 </s> add 
        # Ensure source 4 is added, and everything else is as expected
          obj = serializer.save()
          self.assertEquals(serializer.data, data)
          self.assertEqual(obj.name, u'source-4')
  
        # Ensure source 4 is added, and everything else is as expected
          queryset = ForeignKeySource.objects.all()
          serializer = ForeignKeySourceSerializer(queryset)
          expected = [
              {'id': 1, 'name': u'source-1', 'target': 1},
              {'id': 2, 'name': u'source-2', 'target': 1},
keep keep keep keep replace keep keep keep keep keep
 Don't persist relation changes in ModelSerializer#restore_object() 
rest_framework/tests/relations_pk.py