'Ensure we can search for a specific generic reference by
providing its ObjectId.'

def test_generic_reference_filter_by_dbref(self):

    class Doc(Document, ):
        ref = GenericReferenceField()
    Doc.drop_collection()
    doc1 = Doc.objects.create()
    doc2 = Doc.objects.create(ref=doc1)
    doc = Doc.objects.get(ref=DBRef('doc', doc1.pk))
    self.assertEqual(doc, doc2)
