Use base64.decodebytes() and base64.encodebytes(). [Issue #338]

This commit also adds test coverage for tsigkeyring, and fixes to_text()
on python 3, which had never worked properly due to an extra .decode().

dns/tsigkeyring.py

@@ -30,7 +30,7 @@ def from_text(textring):
     keyring = {}
     for keytext in textring:
         keyname = dns.name.from_text(keytext)
-        secret = base64.decodestring(textring[keytext].encode())
+        secret = base64.decodebytes(textring[keytext].encode())
         keyring[keyname] = secret
     return keyring
 
@@ -42,7 +42,8 @@ def to_text(keyring):
 
     textring = {}
     for keyname in keyring:
-        keytext = keyname.to_text().decode()
-        secret = base64.encodestring(keyring[keyname]).decode()
+        keytext = keyname.to_text()
+        # rstrip to get rid of the \n encoding adds
+        secret = base64.encodebytes(keyring[keyname]).decode().rstrip()
         textring[keytext] = secret
     return textring

tests/test_tsigkeyring.py

@@ -0,0 +1,33 @@
+# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
+
+import base64
+import unittest
+
+import dns.tsigkeyring
+
+text_keyring = {
+    'keyname.' : 'NjHwPsMKjdN++dOfE5iAiQ=='
+}
+
+rich_keyring = {
+    dns.name.from_text('keyname.') : \
+    base64.decodebytes('NjHwPsMKjdN++dOfE5iAiQ=='.encode())
+}
+
+class TSIGKeyRingTestCase(unittest.TestCase):
+
+    def test_from_text(self):
+        """text keyring -> rich keyring"""
+        rkeyring = dns.tsigkeyring.from_text(text_keyring)
+        self.assertEqual(rkeyring, rich_keyring)
+
+    def test_to_text(self):
+        """text keyring -> rich keyring -> text keyring"""
+        tkeyring = dns.tsigkeyring.to_text(rich_keyring)
+        self.assertEqual(tkeyring, text_keyring)
+
+    def test_from_and_to_text(self):
+        """text keyring -> rich keyring -> text keyring"""
+        rkeyring = dns.tsigkeyring.from_text(text_keyring)
+        tkeyring = dns.tsigkeyring.to_text(rkeyring)
+        self.assertEqual(tkeyring, text_keyring)