Add a PyLint CI pipeline

Author: Gallaecio

.travis.yml

@@ -1,10 +1,19 @@
 language: python
-python:
-- '2.7'
-- '3.4'
-- '3.5'
-- '3.6'
-- '3.7'
+sudo: false
+matrix:
+  include:
+    - python: 3.7
+      env: TOXENV=pylint
+    - python: 2.7
+      env: TOXENV=py27
+    - python: 3.4
+      env: TOXENV=py34
+    - python: 3.5
+      env: TOXENV=py35
+    - python: 3.6
+      env: TOXENV=py36
+    - python: 3.7
+      env: TOXENV=py37
 install:
 - pip install -r tests/requirements.txt -e .
 script:
@@ -21,4 +30,4 @@ deploy:
   on:
     tags: true
     repo: scrapy/cssselect
-    condition: "$TRAVIS_PYTHON_VERSION == '3.7'"
+    condition: "$TOXENV == py37"

pylintrc

@@ -0,0 +1,33 @@
+[MASTER]
+persistent=no
+
+[MESSAGES CONTROL]
+disable=assignment-from-no-return,
+        bad-continuation,
+        bad-whitespace,
+        c-extension-no-member,
+        consider-using-in,
+        fixme,
+        inconsistent-return-statements,
+        invalid-name,
+        missing-class-docstring,
+        missing-function-docstring,
+        missing-module-docstring,
+        multiple-imports,
+        no-else-return,
+        no-member,
+        no-self-use,
+        redefined-builtin,
+        redefined-outer-name,
+        too-few-public-methods,
+        too-many-arguments,
+        too-many-branches,
+        too-many-function-args,
+        too-many-lines,
+        too-many-public-methods,
+        too-many-statements,
+        undefined-variable,
+        unidiomatic-typecheck,
+        unused-argument,
+        unused-import,
+        useless-object-inheritance  # Required for Python 2 support

tox.ini

@@ -7,3 +7,11 @@ deps=
 
 commands =
     py.test --cov-report term --cov=cssselect
+
+[testenv:pylint]
+basepython = python3.7
+deps =
+    {[testenv]deps}
+    pylint
+commands =
+    pylint cssselect docs setup.py tests