Add Rubocop

Quickly setup Rubocop on a Rails app:

bundle add rubocop && printf "AllCops:\n NewCops: enable\n SuggestExtensions: false\n\nStyle/Documentation:\n Enabled: false\n\nStyle/FetchEnvVar:\n Enabled: false\n\nMetrics/MethodLength:\n Enabled: false\n\nLayout/LineLength:\n Max: 120\n\nMetrics/BlockLength:\n Enabled: false\n\n\nLint/EmptyBlock:\n  Enabled: false\n\n" >> .rubocop.yml && printf '#!/usr/bin/env ruby\n# frozen_string_literal: true\n\n#\n# This file was generated by Bundler.\n#\n# The application 'rubocop' is installed as part of a gem, and\n# this file is here to facilitate running it.\n#\n\nrequire "pathname"\nENV["BUNDLE_GEMFILE"] ||= File.expand_path("../../Gemfile",\n\n\nbundle_binstub = File.expand_path("../bundle", __FILE__)\n\nif File.file?(bundle_binstub)\n  if, 300) =~ /This file was generated by Bundler/\n    load(bundle_binstub)\n  else\n    abort("Your `bin/bundle` was not generated by Bundler, so this binstub cannot run.\nReplace `bin/bundle` by running `bundle binstubs bundler --force`, then run this command again.")\n  end\nend\n\nrequire "rubygems"\nrequire "bundler/setup"\n\nload Gem.bin_path("rubocop", "rubocop")' >> bin/rubocop && chmod 0755 bin/rubocop && git add . && git commit -m "adds rubocop" && (bin/rubocop -A) || git add . && git commit -m "rubocop autocorrections" 

Run Rubocop with bin/rubocop -A . When running Rubocop, you can add the -A to make autocorrections, but this has just been done for you in the above script.

You will be left with 3 Rubocop linting errors. In bin/bundle, replace the method cli_arg_version with

  def cli_arg_version
    return unless invoked_as_script? # don't want to hijack other binstubs
    return unless 'update'.start_with?(ARGV.first || ' ') # must be running `bundle update`

    update_index = nil
    loop_through_args(update_index: update_index)

  def loop_through_args(update_index:, bundler_version: nil)
    ARGV.each_with_index do |a, i|
      bundler_version = a if update_index && update_index.succ == i && a =~ Gem::Version::ANCHORED_VERSION_PATTERN
      next unless a =~ /\A--bundler(?:[= ](#{Gem::Version::VERSION_PATTERN}))?\z/

      bundler_version = Regexp.last_match(1)
      update_index = i

Run bin/rubocop -A again and you should have 1 remaining lint error, also in bin/bundle on line 107.

The line is too long, so surround 107 with:

    + "bundler this project requires, run `gem install bundler -v '#{bundler_requirement}'`"

Then run bin/rubocop -A again and you will see an Asignment Branch Conditional error on the method activate_bundler inside of bin/bundle.

Disable this on the method by adding this comment above the line def activate_bundler

# rubocop:disable Metrics/AbcSize

Be sure to re-enable the cop below the end cooresponding to this method (around line 111)

# rubocop:enable Metrics/AbcSize

Finally, run bin/rubocop -A again and your code should be completely linted: