rubocop v0.71.0 - sane config and automation

.rubocop.yml

require:
  - ./spec/linters/migrations/migration_linting.rb
  - rubocop-rails
  - rubocop-rspec

AllCops:
  TargetRubyVersion: 2.4
  UseCache: true
  CacheRootDirectory: ./.rubocop-cache
  Exclude:
    - node_modules/**/*
    - vendor/**/*
    - lib/*/node_modules/**/*
    - tmp/*

Lint/Debugger:
  Enabled: true
  Exclude: []

# Commonly used screens these days easily fit more than 80 characters.
Metrics/LineLength:
  Max: 120

Metrics/MethodLength:
  Max: 20
  ExcludedMethods:
  - it
  - describe
  - context
  - feature
  - freeze
  - specify
  - define
  - renum

Metrics/ClassLength:
  Max: 160

# allow developer's preference on this
Style/StringLiterals:
  Enabled: false

# We do not need to support Ruby 1.9, so this is good to use.
Style/SymbolArray:
  Enabled: true

# prefer inject/detect over reduce/find (more common in the community)
Style/CollectionMethods:
  Enabled: true
  PreferredMethods:
    find: detect
    reduce: inject
    detect: detect
    inject: inject

# Fail is an alias of raise. Avoid aliases, it's more cognitive load for no gain.
# The argument that fail should be used to abort the program is wrong too,
# there's Kernel#abort for that.
Style/SignalException:
  EnforcedStyle: only_raise

# No space makes the method definition shorter and differentiates
# from a regular assignment.
Layout/SpaceAroundEqualsInParameterDefault:
  EnforcedStyle: no_space

Style/BlockDelimiters:
  IgnoredMethods:
  - let
  - let!
  - subject
  - lambda
  - proc
  - it
  - expect

# do / end blocks should be used for side effects,
# methods that run a block for side effects and have
# a useful return value are rare, assign the return
# value to a local variable for those cases.
Style/MethodCalledOnDoEndBlock:
  Enabled: true

# Do not enforce single-character naming of parameters for single-line blocks.
Style/SingleLineBlockParams:
  Enabled: false

# better readability
Layout/IndentFirstHashElement:
  EnforcedStyle: consistent

# better readability - do not mix hash rockets with `:`
Style/HashSyntax:
  EnforcedStyle: ruby19_no_mixed_keys

RSpec/Focus:
  Enabled: true
  Exclude: []

Rails/Output:
  Enabled: true
  Exclude: []

# use find_each whenever possible for performance reasons
Rails/FindEach:
  Enabled: true
  Exclude: []

# use uniq.pluck instead of pluck.uniq where possible
Rails/UniqBeforePluck:
  Enabled: true
  Exclude: []

Migration/AddIndexMustUseConcurrently:
  Enabled: true
  Exclude: []

Migration/MustDisableDdlTransaction:
  Enabled: true
  Exclude: []

Migration/AddReferenceCantUseIndex:
  Enabled: true
  Exclude: []

## Cops disabled or autocorrect disabled as safe-auto-correct is unsafe

# https://github.com/rubocop/rubocop/issues/7287
Style/FrozenStringLiteralComment:
  Enabled: false
  
# https://github.com/rubocop/rubocop/issues/7766
Naming/RescuedExceptionsVariableName:
  AutoCorrect: false

# String#% is by far the least verbose and only object oriented variant.
# https://github.com/rubocop/rubocop/issues/7130
Style/FormatString:
  EnforcedStyle: percent
  AutoCorrect: false

automate_rubocop.rb

# encode: UTF-8
# frozen_string_literal: true

require 'pry'
require 'yaml'
require 'rubocop'
require 'rubocop-rspec'
require 'rubocop-rails'

module RuboCop
  class AutocorrectAutomation
    SEARCHABLE = [RuboCop::Cop, RuboCop::Cop::Rails, RuboCop::Cop::RSpec].freeze
    RUBOCOP = 'bundle exec rubocop --require rubocop-rspec --require rubocop-rails'

    def initialize(opts={})
      @klasses = {}
      @allowed = {}
      @unsafe = opts.fetch(:unsafe, false)
      @run_tests = opts.fetch(:run_tests, true)

      @main = File.expand_path(opts.fetch(:main, '../.rubocop.yml'), __dir__)
      @todo = File.expand_path(opts.fetch(:todo, '../.rubocop_todo.yml'), __dir__)
      @default_config = RuboCop::ConfigLoader.default_configuration

      @config = { @main => YAML.load_file(@main), @todo => YAML.load_file(@todo) }
    end

    def run
      puts "====> Run tests: #{@run_tests ? 'Yes' : 'No'}"
      puts "====> RuboCop mode: #{@unsafe ? :unsafe : :safe}"
      puts "====> RuboCop version: #{RuboCop::Version.version}"

      puts '====> Generating auto config from rubocop..'
      # regenerate_todo_config unless File.exist?(@todo)
      remove_inheritance_from_rubocop_todo

      puts '====> Reading TODO configuration from rubocop for a list of issues..'
      find_classes_for_cops
      filter_for_allowed_cops

      @allowed.each_with_index do |(cop, _), idx|
        print "==> COP #{'%03d' % (idx + 1)}/#{@allowed.count}: #{'%-60s' % cop}"
        run_autocorrect_for(cop)
      end

      puts '====> Re-generate auto config from rubocop with now uncorrectable issues..'
      # regenerate_todo_config

      puts '=> Done.'
    end

    def run_autocorrect_for(cop)
      modified = `#{RUBOCOP} --auto-correct --only #{cop} --format files`.split("\n")
      print ' ✅️' # running autocorrect

      if modified.empty? # no auto correction was required
        on_no_modification(cop)
      elsif @run_tests
        `RAILS_ENV=test bundle exec rspec 2>&1 >/dev/null`
        $CHILD_STATUS.exitstatus.zero? ? on_test_success(cop) : on_test_failure(cop)
      else
        on_test_skipped(cop)
      end
    end

    def list_unsafe_autocorrecting_cops
      @klasses.select { |cop, _| unsafe_autocorrect?(cop) }
    end

    protected

    def on_no_modification(cop)
      puts ' 💚'

      @config[@todo].delete(cop)
      save_config

      add_rubocop_commit :skipped, cop
    end

    def on_test_success(cop)
      puts ' ✅'

      @config[@todo].delete(cop)
      save_config

      add_rubocop_commit :ran, cop
    end

    def on_test_failure(cop)
      puts ' ❌'
      `git add . && git reset --hard`

      @config[@main][cop] ||= {}
      @config[@main][cop].merge!('Enabled' => true, 'AutoCorrect' => false)
      save_config

      add_rubocop_commit :failed, cop
    end

    def on_test_skipped(cop)
      puts
      @config[@todo].delete(cop)
      save_config

      add_rubocop_commit :ran, cop
    end

    def add_rubocop_commit(action, cop)
      safety = safe_autocorrect?(cop) ? '' : ' (unsafe)'
      tests = @run_tests ? '' : ' (tests skipped)'

      message = "rubocop: #{action} autocorrect for cop: #{cop}#{safety}#{tests}"
      `git add . && git commit -m "#{message}" 2>&1 >/dev/null`
    end

    def regenerate_todo_config
      `#{RUBOCOP} --auto-gen-config --exclude-limit=10000`
    end

    private

    def save_config
      @config.each do |path, conf|
        File.open(path, 'w') { |f| f.puts conf.to_yaml }
      end
    end

    def remove_inheritance_from_rubocop_todo(key='inherit_from')
      data = @config[@main][key]
      data = [data].flatten.compact
      # dirty-check
      data = data.reject { |f| !f || File.basename(f) == File.basename(@todo) }
      @config[@main].delete(key) if data.empty?
      @config[@main][key] = (data.length > 1 ? data : data.first) if data.any?
      save_config
    end

    def filter_for_allowed_cops
      @allowed = @klasses.select do |cop, _|
        @unsafe ? support_autocorrect?(cop) : safe_autocorrect?(cop)
      end
    end

    def find_classes_for_cops
      @klasses = @config[@todo].map do |cop, _|
        klass = SEARCHABLE.map do |mod|
          begin
            mod.const_get(cop.gsub('/', '::'))
          rescue NameError
            nil
          end
        end.compact.first
        [cop, klass]
      end.to_h
    end

    def support_autocorrect?(cop)
      inst = @klasses[cop].new
      valid = inst.respond_to?(:support_autocorrect?, true) && inst.support_autocorrect?
      valid && (@config[@main][cop] || {}).fetch('AutoCorrect', true)
    end

    def safe_autocorrect?(cop)
      return false unless support_autocorrect?(cop)

      conf = @default_config[cop]
      conf.fetch('Safe', true) && conf.fetch('SafeAutoCorrect', true)
    end

    def unsafe_autocorrect?(cop)
      support_autocorrect?(cop) && !safe_autocorrect?(cop)
    end
  end
end

# run this automation
require 'optparse'

options = {}
OptionParser.new do |opts|
  opts.banner = 'Usage: bundle exec ruby rubocop_automate.rb [options]'

  opts.on('-U', '--[no-]unsafe', 'Run unsafe autocorrections') do |n|
    options[:unsafe] = n
  end
  opts.on('-T', '--[no-]skip-tests', 'Skip running tests after each autocorrection') do |n|
    options[:run_tests] = !n
  end
end.parse!

RuboCop::AutocorrectAutomation.new(options).run