cq/scripts/slave/step/json_check_step.py

"""Build step class for validating JSON files."""

from __future__ import absolute_import
import collections
import json
import os
import re

from helpers import git_utils
from slave import base_step

_JSON_PARSE_ERROR_MSG = 'This JSON file failed to parse. {}'
_JSON_ERROR_POSITION_PATTERN = r'line (?P<linenum>\d+) column \d+'


class JsonCheckStep(base_step.BaseStep):
  """Build step class for validating JSON files."""

  def __init__(self, **kwargs):
    """Creates a JsonCheckStep instance.

    Args:
      **kwargs: Any additional args to pass to BaseStep.
    """
    base_step.BaseStep.__init__(self, name='json check', **kwargs)

  def _value_error_to_comment(self, err):
    comment = {'message': _JSON_PARSE_ERROR_MSG.format(str(err))}
    match = re.search(_JSON_ERROR_POSITION_PATTERN, str(err))
    if match:
      comment['line'] = match.group('linenum')
    return comment

  def run(self):
    """Attempts to parse all .json files in the current commit.

    Sets a build property "review" with the output if there are any errors.

    Returns:
      True iff there were no parsing errors.
    """
    comments = collections.defaultdict(list)
    for json_filename in self.changed_files(file_extensions=['.json']):
      with open(os.path.join(self.directory, json_filename)) as json_file:
        try:
          json.load(json_file)
        except ValueError as err:
          comments[json_filename].append(self._value_error_to_comment(err))

    if comments:
      self.add_review({'comments': comments})
      return False

    # No Errors
    return True