def testDerCodec(self):
        layers = { }
        layers.update(rfc5652.cmsContentTypesMap)

        getNextLayer = {
            rfc5652.id_ct_contentInfo: lambda x: x['contentType'],
            rfc5652.id_signedData: lambda x: x['encapContentInfo']['eContentType'],
            rfc6402.id_cct_PKIData: lambda x: None
        }

        getNextSubstrate = {
            rfc5652.id_ct_contentInfo: lambda x: x['content'],
            rfc5652.id_signedData: lambda x: x['encapContentInfo']['eContent'],
            rfc6402.id_cct_PKIData: lambda x: None
        }

        substrate = pem.readBase64fromText(self.pem_text)

        next_layer = rfc5652.id_ct_contentInfo
        while next_layer:
            asn1Object, rest = der_decoder(substrate, asn1Spec=layers[next_layer])
            self.assertFalse(rest)
            self.assertTrue(asn1Object.prettyPrint())
            self.assertEqual(substrate, der_encoder(asn1Object))

            substrate = getNextSubstrate[next_layer](asn1Object)
            next_layer = getNextLayer[next_layer](asn1Object)