def test_algorithmDefaultAttribute(self):
        """
        L{dns.Record_CERT.algorithm} is a public L{int} attribute
        whose default value is 5 (RSA/SHA-1).

        Values are defined in DNSSEC
        https://tools.ietf.org/html/rfc4034#section-2.1.3
        """
        record = dns.Record_CERT()
        self.assertEqual(record.algorithm, 5)


    def test_algorithmOverride(self):
        """
        L{dns.Record_CERT.__init__} accepts a C{algorithm}
        parameter which overrides the
        L{dns.Record_CERT.algorithm} attribute.
        """
        record = dns.Record_CERT(algorithm=255)
        self.assertEqual(record.algorithm, 255)


    def test_publicKeyAttribute(self):
        """
        L{dns.Record_CERT.publicKey} is a public L{bytes} attribute
        whose default value is C{b''}.

        https://tools.ietf.org/html/rfc4034#section-2.1.4
        """
        record = dns.Record_CERT()
        self.assertEqual(record.publicKey, b'')


    def test_publicKeyOverride(self):
        """
        L{dns.Record_CERT.__init__} accepts a C{publicKey}
        parameter which overrides the
        L{dns.Record_CERT.publicKey} attribute.
        """
        record = dns.Record_CERT(publicKey=b'foobar')
        self.assertEqual(record.publicKey, b'foobar')


    def test_encode(self):
        """
        L{dns.Record_CERT.encode} packs the header fields and the
        key and writes them to a file like object passed in as an
        argument.
        """
        record = DNSKEY_TEST_DATA.OBJECT()
        actualBytes = BytesIO()
        record.encode(actualBytes)

        self.assertEqual(actualBytes.getvalue(), DNSKEY_TEST_DATA.BYTES())


    def test_decode(self):
        """
        L{dns.Record_CERT.decode} unpacks the header fields from a file
        like object and populates the attributes of an existing
        L{dns.Record_CERT} instance.
        """
        expectedBytes = DNSKEY_TEST_DATA.BYTES()
        record = dns.Record_CERT()
        record.decode(BytesIO(expectedBytes), length=len(expectedBytes))

        self.assertEqual(record, DNSKEY_TEST_DATA.OBJECT())


    def test_decodeShorterThanHeader(self):
        """
        L{dns.Record_CERT.decode} raises L{EOFError} if the provided
        file object is shorter than the fixed length header parts. ie
        everything except key.
        """
        record = dns.Record_CERT()

        self.assertRaises(EOFError, record.decode, BytesIO(b'x'), length=1)


    def test_decodeShorterThanKey(self):
        """
        L{dns.Record_CERT.decode} raises L{EOFError} if the provided
        file object is shorter than length provided in the length
        argument.
        """
        expectedBytes = DNSKEY_TEST_DATA.BYTES()
        record = dns.Record_CERT()

        self.assertRaises(
                EOFError,
                record.decode,
                BytesIO(expectedBytes[:-1]), length=len(expectedBytes))