update to latest pylint (2.0.0) and appease it

.pylintrc

@@ -1,6 +1,7 @@
 # https://docs.pylint.org/en/latest/technical_reference/features.html
 
 [MESSAGES CONTROL]
+disable = useless-object-inheritance
 
 # bidict/_version.py is generated by setuptools_scm
 ignore = _version.py

.travis.yml

@@ -102,11 +102,11 @@ matrix:
         - travis_retry make linkcheck
     - env: TASK=flake8
       before_install: skip
-      install: travis_retry pip install flake8
+      install: travis_retry pip install 'flake8<3.6'  # keep in sync with the pin in setup.py
       script: flake8 $LINT_SRC
     - env: TASK=pylint
-      before_install: travis_retry pip install .[test]
-      install: travis_retry pip install pylint
+      before_install: skip
+      install: travis_retry pip install 'pylint<2.1' 'hypothesis<4' 'pytest<4'  # keep in sync with the pins in setup.py
       script: pylint --jobs=0 $LINT_SRC
     - env: TASK=test-with-optimization-flag  # make sure there are no relied-on side effects in assert statements
       before_install: skip

bidict/_orderedbase.py

@@ -114,7 +114,7 @@ class _Node(object):  # pylint: disable=too-few-public-methods
         vork = self._vork
         if key_or_val == korv:
             return vork
-        elif key_or_val == vork:
+        if key_or_val == vork:
             return korv
         raise KeyError(key_or_val)
 

bidict/compat.py

@@ -82,7 +82,7 @@ if PY2:
 
     # In Python 3, the collections ABCs were moved into collections.abc, which does not exist in
     # Python 2. Support for importing them directly from collections is dropped in Python 3.8.
-    from collections import (  # noqa: F401 (imported but unused)
+    from collections import (  # pylint: disable=no-name-in-module; noqa: F401 (imported but unused)
         Mapping, MutableMapping, KeysView, ItemsView)
 
 else:

setup.cfg

@@ -1,7 +1,7 @@
 [aliases]
 test=pytest
 
-; https://flake8.readthedocs.io/en/latest/config.html
+; http://flake8.pycqa.org/en/latest/user/configuration.html
 [flake8]
 ignore = E126,E128,E265,E731
 max-line-length = 100

setup.py

@@ -68,12 +68,12 @@ DOCS_REQS = [
 DEV_REQ = SETUP_REQS + TEST_REQS + COVERAGE_REQS + DOCS_REQS + [
     'pre-commit<2',
     'tox<4',
-    # Peg to more specific versions of the following dependencies since they'd
-    # have a higher chance of breaking CI otherwise. Upgrade to newer versions
-    # manually to have a chance to fix any resulting breakage.
+    # The following dependencies have a higher chance of suddenly causing CI to fail after updating
+    # even between minor versions so pin to currently-working minor versions. Upgrade to newer
+    # minor versions manually to have a chance to fix any resulting breakage before it hits CI.
     'flake8<3.6',
     'pydocstyle<2.2',
-    'pylint<1.9',
+    'pylint<2.1',
 ]
 
 setup(

tests/test_class_relationships.py

@@ -7,7 +7,10 @@
 
 """Test various issubclass checks."""
 
-from collections import Hashable
+try:
+    from collections import Hashable
+except ImportError:  # Python >= 3.7
+    from collections.abc import Hashable
 
 import pytest
 

tests/test_hypothesis.py

@@ -10,10 +10,13 @@
 import gc
 import pickle
 import re
-from collections import Hashable, Iterable, Mapping, MutableMapping, OrderedDict
 from operator import itemgetter
 from os import getenv
 from weakref import ref
+try:
+    from collections import Hashable, Iterable, Mapping, MutableMapping, OrderedDict
+except ImportError:  # Python >= 3.7
+    from collections.abc import Hashable, Iterable, Mapping, MutableMapping, OrderedDict
 
 import pytest
 from hypothesis import HealthCheck, assume, given, settings, strategies as strat, unlimited