Use pylint

.travis.yml

@@ -7,6 +7,8 @@ branches:
     - /^\d\.\d+\.\d+(rc\d+|\.dev\d+)?$/
 matrix:
   include:
+    - env: TOXENV=pylint
+      python: 3.7
     - env: TOXENV=py27
       python: 2.7
     - env: TOXENV=py27-pinned

docs/utils/linkfix.py

@@ -14,50 +14,57 @@ Author: dufferzafar
 
 import re
 
-# Used for remembering the file (and its contents)
-# so we don't have to open the same file again.
-_filename = None
-_contents = None
 
-# A regex that matches standard linkcheck output lines
-line_re = re.compile(u'(.*)\:\d+\:\s\[(.*)\]\s(?:(.*)\sto\s(.*)|(.*))')
+def main():
 
-# Read lines from the linkcheck output file
-try:
-    with open("build/linkcheck/output.txt") as out:
-        output_lines = out.readlines()
-except IOError:
-    print("linkcheck output not found; please run linkcheck first.")
-    exit(1)
+    # Used for remembering the file (and its contents)
+    # so we don't have to open the same file again.
+    _filename = None
+    _contents = None
 
-# For every line, fix the respective file
-for line in output_lines:
-    match = re.match(line_re, line)
+    # A regex that matches standard linkcheck output lines
+    line_re = re.compile(u'(.*)\:\d+\:\s\[(.*)\]\s(?:(.*)\sto\s(.*)|(.*))')
 
-    if match:
-        newfilename = match.group(1)
-        errortype = match.group(2)
+    # Read lines from the linkcheck output file
+    try:
+        with open("build/linkcheck/output.txt") as out:
+            output_lines = out.readlines()
+    except IOError:
+        print("linkcheck output not found; please run linkcheck first.")
+        exit(1)
 
-        # Broken links can't be fixed and
-        # I am not sure what do with the local ones.
-        if errortype.lower() in ["broken", "local"]:
-            print("Not Fixed: " + line)
+    # For every line, fix the respective file
+    for line in output_lines:
+        match = re.match(line_re, line)
+
+        if match:
+            newfilename = match.group(1)
+            errortype = match.group(2)
+
+            # Broken links can't be fixed and
+            # I am not sure what do with the local ones.
+            if errortype.lower() in ["broken", "local"]:
+                print("Not Fixed: " + line)
+            else:
+                # If this is a new file
+                if newfilename != _filename:
+
+                    # Update the previous file
+                    if _filename:
+                        with open(_filename, "w") as _file:
+                            _file.write(_contents)
+
+                    _filename = newfilename
+
+                    # Read the new file to memory
+                    with open(_filename) as _file:
+                        _contents = _file.read()
+
+                _contents = _contents.replace(match.group(3), match.group(4))
         else:
-            # If this is a new file
-            if newfilename != _filename:
+            # We don't understand what the current line means!
+            print("Not Understood: " + line)
 
-                # Update the previous file
-                if _filename:
-                    with open(_filename, "w") as _file:
-                        _file.write(_contents)
 
-                _filename = newfilename
-
-                # Read the new file to memory
-                with open(_filename) as _file:
-                    _contents = _file.read()
-
-            _contents = _contents.replace(match.group(3), match.group(4))
-    else:
-        # We don't understand what the current line means!
-        print("Not Understood: " + line)
+if __name__ == '__main__':
+    main()

pylintrc

@@ -0,0 +1,88 @@
+[MASTER]
+persistent=no
+jobs=1  # >1 hides results
+
+[MESSAGES CONTROL]
+disable=abstract-method,
+        anomalous-backslash-in-string,
+        arguments-differ,
+        attribute-defined-outside-init,
+        bad-classmethod-argument,
+        bad-continuation,
+        bad-indentation,
+        bad-mcs-classmethod-argument,
+        bad-whitespace,
+        broad-except,
+        c-extension-no-member,
+        catching-non-exception,
+        cell-var-from-loop,
+        comparison-with-callable,
+        consider-using-in,
+        cyclic-import,
+        dangerous-default-value,
+        deprecated-method,
+        deprecated-module,
+        duplicate-code,  # https://github.com/PyCQA/pylint/issues/214
+        eval-used,
+        expression-not-assigned,
+        fixme,
+        function-redefined,
+        global-statement,
+        import-error,
+        import-outside-toplevel,
+        inconsistent-return-statements,
+        inherit-non-class,
+        invalid-name,
+        keyword-arg-before-vararg,
+        line-too-long,
+        logging-format-interpolation,
+        logging-not-lazy,
+        lost-exception,
+        method-hidden,
+        missing-docstring,
+        missing-final-newline,
+        multiple-imports,
+        multiple-statements,
+        no-else-continue,
+        no-else-raise,
+        no-else-return,
+        no-init,
+        no-member,
+        no-method-argument,
+        no-name-in-module,
+        no-self-argument,
+        no-self-use,
+        pointless-string-statement,
+        protected-access,
+        redefined-argument-from-local,
+        redefined-builtin,
+        redefined-outer-name,
+        reimported,
+        signature-differs,
+        super-init-not-called,
+        superfluous-parens,
+        too-few-public-methods,
+        too-many-ancestors,
+        too-many-arguments,
+        too-many-branches,
+        too-many-function-args,
+        too-many-instance-attributes,
+        too-many-locals,
+        too-many-return-statements,
+        trailing-newlines,
+        trailing-whitespace,
+        unexpected-special-method-signature,
+        ungrouped-imports,
+        unidiomatic-typecheck,
+        unnecessary-comprehension,
+        unnecessary-pass,
+        unsubscriptable-object,
+        unused-argument,
+        unused-import,
+        unused-variable,
+        unused-wildcard-import,
+        used-before-assignment,
+        useless-object-inheritance,  # Required for Python 2 support
+        wildcard-import,
+        wrong-import-order,
+        wrong-import-position

tox.ini

@@ -98,6 +98,20 @@ deps = {[testenv:py35]deps}
 commands =
     py.test {posargs:scrapy tests}
 
+[testenv:pylint]
+basepython = python3.7
+deps =
+    {[testenv:py35]deps}
+    # Optional dependencies
+    boto
+    reppy
+    robotexclusionrulesparser
+    # Test dependencies
+    pylint
+
+commands =
+    pylint scrapy
+
 [docs]
 changedir = docs
 deps =