Add lintstack error checker based on pylint

Add a new silent test target lintstack based on pylint in Jenkins.
lintstack will compare the pylint errors between HEAD and HEAD~1,
filter out known false positives and report violations in pylint
original parseable format for Jenkins to consume.

Change-Id: Ic2962cb42a174bfe9535aea88475ff4ede3bf9ff

4 files changed, 243 insertions, 1 deletions

diff --git a/tools/lintstack.py b/tools/lintstack.py
new file mode 100755
index 000000000..ce9b6f8a6
--- /dev/null
+++ b/tools/lintstack.py
@@ -0,0 +1,199 @@
+#!/usr/bin/env python
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (c) 2012, AT&T Labs, Yun Mao <yunmao@gmail.com>
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""pylint error checking"""
+
+import cStringIO as StringIO
+import json
+import re
+import sys
+
+from pylint import lint
+from pylint.reporters import text
+
+# Note(maoy): E1103 is error code related to partial type inference
+ignore_codes = ["E1103"]
+# Note(maoy): the error message is the pattern of E0202. It should be ignored
+# for nova.tests modules
+ignore_messages = ["An attribute affected in nova.tests"]
+# Note(maoy): we ignore all errors in openstack.common because it should be
+# checked elsewhere. We also ignore nova.tests for now due to high false
+# positive rate.
+ignore_modules = ["nova/openstack/common/", "nova/tests/"]
+
+KNOWN_PYLINT_EXCEPTIONS_FILE = "tools/pylint_exceptions"
+
+
+class LintOutput(object):
+
+    _cached_filename = None
+    _cached_content = None
+
+    def __init__(self, filename, lineno, line_content, code, message,
+                 lintoutput):
+        self.filename = filename
+        self.lineno = lineno
+        self.line_content = line_content
+        self.code = code
+        self.message = message
+        self.lintoutput = lintoutput
+
+    @classmethod
+    def from_line(cls, line):
+        m = re.search(r"(\S+):(\d+): \[(\S+)(, \S+)?] (.*)", line)
+        matched = m.groups()
+        filename, lineno, code, message = (matched[0], int(matched[1]),
+                                           matched[2], matched[-1])
+        if cls._cached_filename != filename:
+            with open(filename) as f:
+                cls._cached_content = list(f.readlines())
+                cls._cached_filename = filename
+        line_content = cls._cached_content[lineno - 1].rstrip()
+        return cls(filename, lineno, line_content, code, message,
+                   line.rstrip())
+
+    @classmethod
+    def from_msg_to_dict(cls, msg):
+        """From the output of pylint msg, to a dict, where each key
+        is a unique error identifier, value is a list of LintOutput
+        """
+        result = {}
+        for line in msg.splitlines():
+            obj = cls.from_line(line)
+            if obj.is_ignored():
+                continue
+            key = obj.key()
+            if key not in result:
+                result[key] = []
+            result[key].append(obj)
+        return result
+
+    def is_ignored(self):
+        if self.code in ignore_codes:
+            return True
+        if any(self.filename.startswith(name) for name in ignore_modules):
+            return True
+        if any(msg in self.message for msg in ignore_messages):
+            return True
+        return False
+
+    def key(self):
+        if self.code in ["E1101", "E1103"]:
+            # These two types of errors are like Foo class has no member bar.
+            # We discard the source code so that the error will be ignored
+            # next time another Foo.bar is encountered.
+            return self.message, ""
+        return self.message, self.line_content.strip()
+
+    def json(self):
+        return json.dumps(self.__dict__)
+
+    def review_str(self):
+        return ("File %(filename)s\nLine %(lineno)d:%(line_content)s\n"
+                "%(code)s: %(message)s" % self.__dict__)
+
+
+class ErrorKeys(object):
+
+    @classmethod
+    def print_json(cls, errors, output=sys.stdout):
+        print >>output, "# automatically generated by tools/lintstack.py"
+        for i in sorted(errors.keys()):
+            print >>output, json.dumps(i)
+
+    @classmethod
+    def from_file(cls, filename):
+        keys = set()
+        for line in open(filename):
+            if line and line[0] != "#":
+                d = json.loads(line)
+                keys.add(tuple(d))
+        return keys
+
+
+def run_pylint():
+    buff = StringIO.StringIO()
+    reporter = text.ParseableTextReporter(output=buff)
+    args = ["--include-ids=y", "-E", "nova"]
+    lint.Run(args, reporter=reporter, exit=False)
+    val = buff.getvalue()
+    buff.close()
+    return val
+
+
+def generate_error_keys(msg=None):
+    print "Generating", KNOWN_PYLINT_EXCEPTIONS_FILE
+    if msg is None:
+        msg = run_pylint()
+    errors = LintOutput.from_msg_to_dict(msg)
+    with open(KNOWN_PYLINT_EXCEPTIONS_FILE, "w") as f:
+        ErrorKeys.print_json(errors, output=f)
+
+
+def validate(newmsg=None):
+    print "Loading", KNOWN_PYLINT_EXCEPTIONS_FILE
+    known = ErrorKeys.from_file(KNOWN_PYLINT_EXCEPTIONS_FILE)
+    if newmsg is None:
+        print "Running pylint. Be patient..."
+        newmsg = run_pylint()
+    errors = LintOutput.from_msg_to_dict(newmsg)
+
+    print "Unique errors reported by pylint: was %d, now %d." \
+           % (len(known), len(errors))
+    passed = True
+    for err_key, err_list in errors.items():
+        for err in err_list:
+            if err_key not in known:
+                print err.lintoutput
+                print
+                passed = False
+    if passed:
+        print "Congrats! pylint check passed."
+        redundant = known - set(errors.keys())
+        if redundant:
+            print "Extra credit: some known pylint exceptions disappeared."
+            for i in sorted(redundant):
+                print json.dumps(i)
+            print "Consider regenerating the exception file if you will."
+    else:
+        print ("Please fix the errors above. If you believe they are false"
+              " positives, run 'tools/lintstack.py generate' to overwrite.")
+        sys.exit(1)
+
+
+def usage():
+    print """Usage: tools/lintstack.py [generate|validate]
+    To generate pylint_exceptions file: tools/lintstack.py generate
+    To validate the current commit: tools/lintstack.py
+    """
+
+
+def main():
+    option = "validate"
+    if len(sys.argv) > 1:
+        option = sys.argv[1]
+    if option == "generate":
+        generate_error_keys()
+    elif option == "validate":
+        validate()
+    else:
+        usage()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/lintstack.sh b/tools/lintstack.sh
new file mode 100755
index 000000000..848a16fa5
--- /dev/null
+++ b/tools/lintstack.sh
@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+
+# Copyright (c) 2012, AT&T Labs, Yun Mao <yunmao@gmail.com>
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+# Use lintstack.py to compare pylint errors between HEAD and HEAD~1
+
+set -e
+TOOLS_DIR=$(cd $(dirname "$0") && pwd)
+GITHEAD=`git rev-parse HEAD`
+cp -f $TOOLS_DIR/lintstack.py $TOOLS_DIR/lintstack.head.py
+git checkout HEAD~1
+# First generate tools/pylint_exceptions from HEAD~1
+$TOOLS_DIR/lintstack.head.py generate
+# Then use that as a reference to compare against HEAD
+git checkout $GITHEAD
+$TOOLS_DIR/lintstack.head.py
+echo "Check passed. FYI: the pylint exceptions are:"
+cat $TOOLS_DIR/pylint_exceptions
+echo
+echo "You are in detached HEAD mode. If you are a developer"
+echo "and not very familiar with git, you might want to do"
+echo "'git checkout branch-name' to go back to your branch."
+
diff --git a/tools/test-requires b/tools/test-requires
index 279e87636..0591d5026 100644
--- a/tools/test-requires
+++ b/tools/test-requires
@@ -6,5 +6,6 @@ mox==0.5.3
 nose
 openstack.nose_plugin>=0.7
 pep8==1.1
+pylint==0.25.2
 sphinx>=1.1.2
 feedparser
diff --git a/tox.ini b/tox.ini
index 4957ce39a..9e454472b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py26,py27,pep8
+envlist = py26,py27,pep8,pylint
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
@@ -26,6 +26,12 @@ commands =
   python tools/hacking.py --ignore=N4 --repeat --show-source \
     --exclude=.venv,.tox,dist,doc,*openstack/common*,*lib/python*,*egg .
 
+[testenv:pylint]
+setenv = VIRTUAL_ENV={envdir}
+deps = -r{toxinidir}/tools/pip-requires
+       pylint==0.25.2
+commands = bash tools/lintstack.sh
+
 [testenv:cover]
 setenv = NOSE_WITH_COVERAGE=1