Fix Pylint upgrade issues

* Remove unsupported pylint disable options
    * star-args removed in Pylint 1.4.3
    * abstract-class-little-used removed in Pylint 1.4.3

* Fixes new lint errors

* Copy dummy-variable-rgx expression to new ignored-argument-names expression to ignore unused funtion arguments

* Notable changes
    * Refactor to satisfy Pylint no-else-return warning
    * Fix Pylint inconsistent-return-statements warning
    * Refactor to satisfy consider-iterating-dictionary
    * Remove methods with only super call to satisfy useless-super-delegation
    * Refactor too-many-nested-statements where possible
    * Suppress type checked errors where member is dynamically added (notably derived from josepy.JSONObjectWithFields)
    * Remove None default of func parameter for ExitHandler and ErrorHandler

Resolves #5973

acme/acme/challenges.py

@@ -95,6 +95,7 @@ class _TokenChallenge(Challenge):
         """
         # TODO: check that path combined with uri does not go above
         # URI_ROOT_PATH!
+        # pylint: disable=unsupported-membership-test
         return b'..' not in self.token and b'/' not in self.token
 
 
@@ -142,7 +143,7 @@ class KeyAuthorizationChallengeResponse(ChallengeResponse):
 
 @six.add_metaclass(abc.ABCMeta)
 class KeyAuthorizationChallenge(_TokenChallenge):
-    # pylint: disable=abstract-class-little-used,too-many-ancestors
+    # pylint: disable=too-many-ancestors
     """Challenge based on Key Authorization.
 
     :param response_cls: Subclass of `KeyAuthorizationChallengeResponse`
@@ -174,7 +175,7 @@ class KeyAuthorizationChallenge(_TokenChallenge):
         :rtype: KeyAuthorizationChallengeResponse
 
         """
-        return self.response_cls(
+        return self.response_cls(  # pylint: disable=not-callable
             key_authorization=self.key_authorization(account_key))
 
     @abc.abstractmethod

acme/acme/challenges_test.py

@@ -6,7 +6,7 @@ import mock
 import OpenSSL
 import requests
 
-from six.moves.urllib import parse as urllib_parse  # pylint: disable=import-error
+from six.moves.urllib import parse as urllib_parse  # pylint: disable=import-error,relative-import
 
 from acme import errors
 from acme import test_util

acme/acme/client.py

@@ -6,16 +6,16 @@ from email.utils import parsedate_tz
 import heapq
 import logging
 import time
+import re
+import sys
 
 import six
 from six.moves import http_client  # pylint: disable=import-error
 import josepy as jose
 import OpenSSL
-import re
-from requests_toolbelt.adapters.source import SourceAddressAdapter
 import requests
 from requests.adapters import HTTPAdapter
-import sys
+from requests_toolbelt.adapters.source import SourceAddressAdapter
 
 from acme import crypto_util
 from acme import errors
@@ -134,7 +134,7 @@ class ClientBase(object):  # pylint: disable=too-many-instance-attributes
         authzr = messages.AuthorizationResource(
             body=messages.Authorization.from_json(response.json()),
             uri=response.headers.get('Location', uri))
-        if identifier is not None and authzr.body.identifier != identifier:
+        if identifier is not None and authzr.body.identifier != identifier:  # pylint: disable=no-member
             raise errors.UnexpectedUpdate(authzr)
         return authzr
 
@@ -608,7 +608,7 @@ class ClientV2(ClientBase):
         response = self._post(self.directory['newOrder'], order)
         body = messages.Order.from_json(response.json())
         authorizations = []
-        for url in body.authorizations:
+        for url in body.authorizations:  # pylint: disable=not-an-iterable
             authorizations.append(self._authzr_from_response(self.net.get(url), uri=url))
         return messages.OrderResource(
             body=body,
@@ -640,7 +640,7 @@ class ClientV2(ClientBase):
         for url in orderr.body.authorizations:
             while datetime.datetime.now() < deadline:
                 authzr = self._authzr_from_response(self.net.get(url), uri=url)
-                if authzr.body.status != messages.STATUS_PENDING:
+                if authzr.body.status != messages.STATUS_PENDING:  # pylint: disable=no-member
                     responses.append(authzr)
                     break
                 time.sleep(1)
@@ -654,7 +654,7 @@ class ClientV2(ClientBase):
                 for chall in authzr.body.challenges:
                     if chall.error != None:
                         failed.append(authzr)
-        if len(failed) > 0:
+        if failed:
             raise errors.ValidationError(failed)
         return orderr.update(authorizations=responses)
 
@@ -778,8 +778,7 @@ class BackwardsCompatibleClientV2(object):
             for domain in dnsNames:
                 authorizations.append(self.client.request_domain_challenges(domain))
             return messages.OrderResource(authorizations=authorizations, csr_pem=csr_pem)
-        else:
-            return self.client.new_order(csr_pem)
+        return self.client.new_order(csr_pem)
 
     def finalize_order(self, orderr, deadline):
         """Finalize an order and obtain a certificate.
@@ -812,12 +811,11 @@ class BackwardsCompatibleClientV2(object):
                     'certificate, please rerun the command for a new one.')
 
             cert = OpenSSL.crypto.dump_certificate(
-                    OpenSSL.crypto.FILETYPE_PEM, certr.body.wrapped).decode()
+                    OpenSSL.crypto.FILETYPE_PEM, certr.body.wrapped).decode()  # pylint: disable=no-member
             chain = crypto_util.dump_pyopenssl_chain(chain).decode()
 
             return orderr.update(fullchain_pem=(cert + chain))
-        else:
-            return self.client.finalize_order(orderr, deadline)
+        return self.client.finalize_order(orderr, deadline)
 
     def revoke(self, cert, rsn):
         """Revoke certificate.
@@ -835,8 +833,7 @@ class BackwardsCompatibleClientV2(object):
     def _acme_version_from_directory(self, directory):
         if hasattr(directory, 'newNonce'):
             return 2
-        else:
-            return 1
+        return 1
 
 
 class ClientNetwork(object):  # pylint: disable=too-many-instance-attributes
@@ -913,7 +910,6 @@ class ClientNetwork(object):  # pylint: disable=too-many-instance-attributes
             if self.account is not None:
                 kwargs["kid"] = self.account["uri"]
         kwargs["key"] = self.key
-        # pylint: disable=star-args
         return jws.JWS.sign(jobj, **kwargs).json_dumps(indent=2)
 
     @classmethod
@@ -1057,7 +1053,7 @@ class ClientNetwork(object):  # pylint: disable=too-many-instance-attributes
         if self.REPLAY_NONCE_HEADER in response.headers:
             nonce = response.headers[self.REPLAY_NONCE_HEADER]
             try:
-                decoded_nonce = jws.Header._fields['nonce'].decode(nonce)
+                decoded_nonce = jws.Header._fields['nonce'].decode(nonce)  # pylint: disable=no-member
             except jose.DeserializationError as error:
                 raise errors.BadNonce(nonce, error)
             logger.debug('Storing nonce: %s', nonce)

acme/acme/client_test.py

@@ -63,7 +63,7 @@ class ClientTestBase(unittest.TestCase):
         reg = messages.Registration(
             contact=self.contact, key=KEY.public_key())
         the_arg = dict(reg) # type: Dict
-        self.new_reg = messages.NewRegistration(**the_arg) # pylint: disable=star-args
+        self.new_reg = messages.NewRegistration(**the_arg)
         self.regr = messages.RegistrationResource(
             body=reg, uri='https://www.letsencrypt-demo.org/acme/reg/1')
 
@@ -403,7 +403,7 @@ class ClientTest(ClientTestBase):
 
     def test_answer_challenge(self):
         self.response.links['up'] = {'url': self.challr.authzr_uri}
-        self.response.json.return_value = self.challr.body.to_json()
+        self.response.json.return_value = self.challr.body.to_json()  # pylint: disable=no-member
 
         chall_response = challenges.DNSResponse(validation=None)
 
@@ -411,7 +411,7 @@ class ClientTest(ClientTestBase):
 
         # TODO: split here and separate test
         self.assertRaises(errors.UnexpectedUpdate, self.client.answer_challenge,
-                          self.challr.body.update(uri='foo'), chall_response)
+                          self.challr.body.update(uri='foo'), chall_response)  # pylint: disable=no-member
 
     def test_answer_challenge_missing_next(self):
         self.assertRaises(
@@ -465,7 +465,7 @@ class ClientTest(ClientTestBase):
             self.client.retry_after(response=self.response, default=10))
 
     def test_poll(self):
-        self.response.json.return_value = self.authzr.body.to_json()
+        self.response.json.return_value = self.authzr.body.to_json()  # pylint: disable=no-member
         self.assertEqual((self.authzr, self.response),
                          self.client.poll(self.authzr))
 
@@ -694,7 +694,7 @@ class ClientV2Test(ClientTestBase):
 
     def test_new_account(self):
         self.response.status_code = http_client.CREATED
-        self.response.json.return_value = self.regr.body.to_json()
+        self.response.json.return_value = self.regr.body.to_json()  # pylint: disable=no-member
         self.response.headers['Location'] = self.regr.uri
 
         self.assertEqual(self.regr, self.client.new_account(self.new_reg))
@@ -743,7 +743,7 @@ class ClientV2Test(ClientTestBase):
 
     def test_poll_authorizations_failure(self):
         deadline = datetime.datetime(9999, 9, 9)
-        challb = self.challr.body.update(status=messages.STATUS_INVALID,
+        challb = self.challr.body.update(status=messages.STATUS_INVALID,  # pylint: disable=no-member
                                          error=messages.Error.with_code('unauthorized'))
         authz = self.authz.update(status=messages.STATUS_INVALID, challenges=(challb,))
         self.response.json.return_value = authz.to_json()
@@ -799,7 +799,7 @@ class MockJSONDeSerializable(jose.JSONDeSerializable):
         return {'foo': self.value}
 
     @classmethod
-    def from_json(cls, value):
+    def from_json(cls, jobj):
         pass  # pragma: no cover
 
 
@@ -829,7 +829,7 @@ class ClientNetworkTest(unittest.TestCase):
             MockJSONDeSerializable('foo'), nonce=b'Tg', url="url",
             acme_version=1)
         jws = acme_jws.JWS.json_loads(jws_dump)
-        self.assertEqual(json.loads(jws.payload.decode()), {'foo': 'foo'})
+        self.assertEqual(json.loads(jws.payload.decode()), {'foo': 'foo'})  # pylint: disable=no-member
         self.assertEqual(jws.signature.combined.nonce, b'Tg')
 
     def test_wrap_in_jws_v2(self):
@@ -839,7 +839,7 @@ class ClientNetworkTest(unittest.TestCase):
             MockJSONDeSerializable('foo'), nonce=b'Tg', url="url",
             acme_version=2)
         jws = acme_jws.JWS.json_loads(jws_dump)
-        self.assertEqual(json.loads(jws.payload.decode()), {'foo': 'foo'})
+        self.assertEqual(json.loads(jws.payload.decode()), {'foo': 'foo'})  # pylint: disable=no-member
         self.assertEqual(jws.signature.combined.nonce, b'Tg')
         self.assertEqual(jws.signature.combined.kid, u'acct-uri')
         self.assertEqual(jws.signature.combined.url, u'url')

acme/acme/crypto_util.py

@@ -138,7 +138,6 @@ def probe_sni(name, host, port=443, timeout=300,
     host_protocol_agnostic = None if host == '::' or host == '0' else host
 
     try:
-        # pylint: disable=star-args
         logger.debug("Attempting to connect to %s:%d%s.", host_protocol_agnostic, port,
             " from {0}:{1}".format(source_address[0], source_address[1]) if \
             socket_kwargs else "")
@@ -194,8 +193,7 @@ def _pyopenssl_cert_or_req_all_names(loaded_cert_or_req):
 
     if common_name is None:
         return sans
-    else:
-        return [common_name] + [d for d in sans if d != common_name]
+    return [common_name] + [d for d in sans if d != common_name]
 
 def _pyopenssl_cert_or_req_san(cert_or_req):
     """Get Subject Alternative Names from certificate or CSR using pyOpenSSL.

acme/acme/jws_test.py

@@ -24,7 +24,7 @@ class HeaderTest(unittest.TestCase):
 
     def test_nonce_decoder(self):
         from acme.jws import Header
-        nonce_field = Header._fields['nonce']
+        nonce_field = Header._fields['nonce']  # pylint: disable=no-member
 
         self.assertRaises(
             jose.DeserializationError, nonce_field.decode, self.wrong_nonce)

acme/acme/messages.py

@@ -40,8 +40,7 @@ def is_acme_error(err):
     """Check if argument is an ACME error."""
     if isinstance(err, Error) and (err.typ is not None):
         return (ERROR_PREFIX in err.typ) or (OLD_ERROR_PREFIX in err.typ)
-    else:
-        return False
+    return False
 
 
 @six.python_2_unicode_compatible
@@ -96,6 +95,7 @@ class Error(jose.JSONObjectWithFields, errors.Error):
         code = str(self.typ).split(':')[-1]
         if code in ERROR_CODES:
             return code
+        return None
 
     def __str__(self):
         return b' :: '.join(
@@ -110,18 +110,19 @@ class _Constant(jose.JSONDeSerializable, collections.Hashable):  # type: ignore
     POSSIBLE_NAMES = NotImplemented
 
     def __init__(self, name):
-        self.POSSIBLE_NAMES[name] = self
+        super(_Constant, self).__init__()
+        self.POSSIBLE_NAMES[name] = self  # pylint: disable=unsupported-assignment-operation
         self.name = name
 
     def to_partial_json(self):
         return self.name
 
     @classmethod
-    def from_json(cls, value):
-        if value not in cls.POSSIBLE_NAMES:
+    def from_json(cls, jobj):
+        if jobj not in cls.POSSIBLE_NAMES:  # pylint: disable=unsupported-membership-test
             raise jose.DeserializationError(
                 '{0} not recognized'.format(cls.__name__))
-        return cls.POSSIBLE_NAMES[value]
+        return cls.POSSIBLE_NAMES[jobj]  # pylint: disable=unsubscriptable-object
 
     def __repr__(self):
         return '{0}({1})'.format(self.__class__.__name__, self.name)
@@ -179,7 +180,6 @@ class Directory(jose.JSONDeSerializable):
 
         def __init__(self, **kwargs):
             kwargs = dict((self._internal_name(k), v) for k, v in kwargs.items())
-            # pylint: disable=star-args
             super(Directory.Meta, self).__init__(**kwargs)
 
         @property
@@ -291,7 +291,7 @@ class Registration(ResourceBody):
 
     def _filter_contact(self, prefix):
         return tuple(
-            detail[len(prefix):] for detail in self.contact
+            detail[len(prefix):] for detail in self.contact  # pylint: disable=not-an-iterable
             if detail.startswith(prefix))
 
     @property
@@ -363,7 +363,6 @@ class ChallengeBody(ResourceBody):
 
     def __init__(self, **kwargs):
         kwargs = dict((self._internal_name(k), v) for k, v in kwargs.items())
-        # pylint: disable=star-args
         super(ChallengeBody, self).__init__(**kwargs)
 
     def encode(self, name):
@@ -446,7 +445,7 @@ class Authorization(ResourceBody):
     def resolved_combinations(self):
         """Combinations with challenges instead of indices."""
         return tuple(tuple(self.challenges[idx] for idx in combo)
-                     for combo in self.combinations)
+                     for combo in self.combinations)  # pylint: disable=not-an-iterable
 
 
 @Directory.register

acme/acme/standalone.py

@@ -82,7 +82,7 @@ class BaseDualNetworkedServers(object):
                 kwargs["ipv6"] = ip_version
                 new_address = (server_address[0],) + (port,) + server_address[2:]
                 new_args = (new_address,) + remaining_args
-                server = ServerClass(*new_args, **kwargs) # pylint: disable=star-args
+                server = ServerClass(*new_args, **kwargs)
             except socket.error:
                 logger.debug("Failed to bind to %s:%s using %s", new_address[0],
                     new_address[1], "IPv6" if ip_version else "IPv4")
@@ -91,7 +91,7 @@ class BaseDualNetworkedServers(object):
                 # If two servers are set up and port 0 was passed in, ensure we always
                 # bind to the same port for both servers.
                 port = server.socket.getsockname()[1]
-        if len(self.servers) == 0:
+        if not self.servers:
             raise socket.error("Could not bind to IPv4 or IPv6.")
 
     def serve_forever(self):

acme/acme/test_util.py

@@ -4,8 +4,8 @@
 
 """
 import os
-import pkg_resources
 import unittest
+import pkg_resources
 
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import serialization
@@ -92,5 +92,4 @@ def skip_unless(condition, reason):  # pragma: no cover
         return unittest.skipUnless(condition, reason)
     elif condition:
         return lambda cls: cls
-    else:
-        return lambda cls: None
+    return lambda cls: None