          Create an instance of a model with a ManyToMany relationship,
          containing no items.
          """
          data = {'rel': []}
          serializer = self.serializer_class(data)
          self.assertEquals(serializer.is_valid(), True)
          instance = serializer.save()
          self.assertEquals(len(ManyToManyModel.objects.all()), 2)
          self.assertEquals(instance.pk, 2)
          self.assertEquals(list(instance.rel.all()), [])
 
</s> remove         serializer = self.not_blank_model_serializer_class(self.data)
 </s> add         serializer = self.not_blank_model_serializer_class(data=self.data) </s> remove         serializer = CommentSerializer(self.data, instance=self.comment)
 </s> add         serializer = CommentSerializer(self.comment, data=self.data) </s> remove         serializer = ManyToManySourceSerializer(instance=queryset)
 </s> add         serializer = ManyToManySourceSerializer(queryset)
        serializer = self.serializer_class(data=data)
          Create an instance of a model with a ManyToMany relationship,
          containing no items.
          """
          data = {'rel': []}
        serializer = self.serializer_class(data=data)
          self.assertEquals(serializer.is_valid(), True)
          instance = serializer.save()
          self.assertEquals(len(ManyToManyModel.objects.all()), 2)
          self.assertEquals(instance.pk, 2)
          self.assertEquals(list(instance.rel.all()), [])
keep keep keep keep replace keep keep keep keep keep
 Swap position of `instance` and `data` keyword arguments. 
rest_framework/tests/serializer.py