breathalyzer -- Run Rubocop on Changed Files in a Git-Managed Directory

breathalyzer

#!/usr/bin/env ruby

##
# Runs rubocop on just the modified and new files in a repoistory. Handy for
# checking your compliance before you commit. It only runs against files that
# end in .rb. Maybe it should do more than that?
#
# Easy to run. In a dirty working directory:
#
#   breathalyzer
#
# It runs rubocop on each dirty file separately.

require 'logger'
require 'optparse'
require 'shellwords'

def git_status(args = nil)
  ##
  # Returns the git status output as an array of strings.
  # Optional args appended to the git status call.
  # Raises an error if git doesn't return a 0 error code.
  git_command = Shellwords.join(%w(git status) + args.split)
  git_output = `#{git_command}`
  fail "git error: #{git_command}" unless $CHILD_STATUS.to_i
  git_output.split("\n")
end

def get_ruby_files(options = {})
  ##
  # Returns a list of ruby files that need to be rubocop'ed
  rubyfiles = []
  git_status('--short').each do |line|
    (status, file) = line.split(' ', 2)
    case status
    when 'M', 'A', 'R', 'C', 'U'
      rubyfiles.push(file) if ruby_file?(file)
    when '??'
      unless options[:exclude_unmanaged]
        rubyfiles.push(file) if ruby_file?(file)
      end
    else
      # Unrecognized status, do nothing
    end
  end
  rubyfiles
end

def ruby_file?(name)
  ##
  # Returns true if this is a file that rubocop can check.
  # Otherwise false.
  File.extname(name).casecmp('.rb') == 0
end

def breathalyzer(options = {})
  ##
  # Run rubocop on some files
  files = get_ruby_files(options)
  if files.length == 0
    puts 'No changes detected, no reason to run rubocop'
  else
    if options[:batch]
      system(Shellwords.join(['rubocop'] + files))
    else
      files.each do |file|
        puts "------ #{file} ------"
        system(Shellwords.join(['rubocop', file]))
        break if options[:stop] && $CHILD_STATUS != 0
      end
    end
  end
end

options = { batch: true, stop: false, exclude_unmanaged: false }

opt_parser = OptionParser.new do |opt|
  script_name = File.basename($PROGRAM_NAME)
  opt.banner = 'Run Rubocop on Changed Files in a Git-Managed Directory'
  opt.separator ''
  opt.define_head(
    '',
    "Usage: #{script_name} [OPTIONS]",
    '',
    'Examples:',
    '',
    '   * Check everything that\'s changed in batch mode',
    "        #{script_name}",
    '',
    '   * Check one file at a time, stop on first violating file',
    "        #{script_name} -os")

  opt.separator ''
  opt.separator 'Options:'

  opt.on(
    '-x',
    '--exclude-unmanaged',
    'exclude unmanaged files from checks?') do
    options[:exclude_unmanaged] = true
  end

  opt.on(
    '-o',
    '--one-at-a-time',
    'run rubocop on file at a time?') do
    options[:batch] = false
  end

  opt.on(
    '-s',
    '--stop-on-error',
    'stop after the first rubocop error?') do
    options[:stop] = true
  end

  opt.on(
    '-h',
    '--help',
    'help') do
    puts opt_parser
    exit 0
  end

  opt.separator ''
  opt.separator 'See Also:'
  opt.separator ''
  opt.separator '   * Rubocop: https://github.com/bbatsov/rubocop'
  opt.separator '   * My Rubocop Settings: https://gist.github.com/ianchesal/352a7963b97a92562a45'
end

opt_parser.parse!

breathalyzer(options)

exit 0