cq/scripts/helpers/pylint.py

"""Script that lints a list of changed files then outputs a list of comments."""

from __future__ import absolute_import
import collections
import logging
import os
import re
import subprocess

# path/to/file.py:27: [E1234(error-name), Text] Error message is here
LINT_WARNING_PATTERN = (r'^(?P<filename>[^:]+):(?P<line_num>\d+): '
                        r'\[(?P<error_code>\w+)\((?P<error_name>.*)\).*\] '
                        r'(?P<error_msg>.*)$')


class PylintError(Exception):
  """Error for the pylint module."""


def RunPylint(changed_files, pylintrc_file=None, cwd=None, executor=None):
  """Runs pylint on a list of changed files.

  Args:
    changed_files: List of files to lint.
    pylintrc_file: Path to a pylintrc file to use with pylint (or None to use
        the default pylintrc from depot_tools).
    cwd: If provided, cwd in which to run pylint.
    executor: If provided, object with which to invoke pylint.

  Returns:
    stdout of the pylint command.

  Raises:
    PylintError: if pylint cannot be found.
  """
  if not changed_files:
    return ''

  pylint = os.path.expanduser('~/depot_tools/pylint')
  if not os.path.exists(pylint):
    logging.error('pylint not installed in expected location: %s', pylint)
    raise PylintError('Could not find pylint.')

  command = [pylint, '--output-format=parseable', '--disable=I']
  if pylintrc_file:
    command += ['--rcfile={}'.format(pylintrc_file)]
  command += changed_files
  if executor:
    _, stdout, _ = executor.exec_subprocess(command, cwd=cwd)
    return stdout

  return subprocess.check_output(command, cwd=cwd)


def ParseLint(lines, cwd=None):
  """Reads lines from lint output and inserts them into comments.

  Args:
    lines: List of lint output lines to parse.
    cwd: Base path relative to which parsed paths should be resolved.
  Returns:
    comments dictionary.
  """
  comments = collections.defaultdict(list)
  for line in lines:
    match = re.match(LINT_WARNING_PATTERN, line)
    if match:
      warning = {
          'line':
              match.group('line_num'),
          'message':
              '{} [{}]'.format(
                  match.group('error_msg'), match.group('error_name'))
      }
      if cwd:
        filename = os.path.relpath(match.group('filename'), cwd)
      else:
        filename = match.group('filename')
      comments[filename].append(warning)

  return comments