All About RuboCop (Saint P RubyConf)

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Привет, ребята!

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Божидар

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Божo cool

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(The RuboCop Guy)

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Sofia, Bulgaria Soﬁa, Bulgaria

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Bulgarian Cheese

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Болгарка

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Слънчев Бряг

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Златни пясъци

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Банско

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Grigor Dimitrov vs Andrey Rublev

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Lukanka

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Rakia Connecting People

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Shopska Salad (use only with Rakia)

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bbatsov

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Ruby & Rails style guides

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First time in SPB!!!

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#RubyKaraoke

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Много городов у нас в России, Нету пальцев столько на ногах,

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С каждым годом всё они красивей, Утопают в солнце и в снегах.

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В Ростове шикарные плюхи, Размером с большую печать,

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В Москве оху*тельно нюхать,

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В Челябинске лучше торчать.

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А в Питере…

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All About RuboCop by Bozhidar Batsov (a.k.a. bug)

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rubocop.readthedocs.io

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Something About RuboCop by Bozhidar Batsov (a.k.a. bug)

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RuboCop in a Nutshell

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A Ruby static code analysis tool aimed to enforce the Ruby Community Style Guide

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In other words…

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It keeps your codebase consistent

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It saves you time

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It advances the Ruby language forward

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32,608,128

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Provides an efﬁcient way for codebases to be updated

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Disclaimer

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Lint tools are not a replacement for common sense

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Why an entire talk about a mere lint tool?

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314 open issues

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100 volunteers

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3.14 issues/person

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Coincidence?

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Or providence?

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A Brief History of Time

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A Brief History of RuboCop

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2011 The Ruby Style Guide

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May, 2012 RuboCop 0.0.0

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May, 2012 RuboCop 0.0.0

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Static code analysis with regular expressions …

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Nov, 2012 Along Came Jonas

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Spring, 2013 Return of the Jedi

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Using a proper parser!

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Struggles with Ripper

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Ripper supported only MRI

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I wanted to build a cross-platform tool

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Ripper had (has?) almost no documentation

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Ripper is tied to the underlying Ruby runtime

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…which means you can’t parse code as Ruby 2.3 while running Ruby 2.5

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Ripper has a very hard to work with AST representation

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pry(main)> Ripper.sexp('alias :some :test') => [:program, [[:alias, [:symbol_literal, [:symbol, [:@ident, "some", [1, 7]]]], [:symbol_literal, [:symbol, [:@ident, "test", [1, 13]]]]]]]

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each(:method_add_arg, sexp) do |s| next if s[1][0] != :call receiver = s[1][1][1] method_name = s[1][3][1] if receiver && receiver[1] == 'Array' && method_name == 'new' && s[2] == [:arg_paren, nil] offences.delete(Offence.new(:convention, receiver[2].lineno, ERROR_MESSAGE)) add_offence(:convention, receiver[2].lineno, ERROR_MESSAGE) end end

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And many quirks…

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pry(main)> Ripper.lex(':one') => [[[1, 0], :on_symbeg, ":"], [[1, 1], :on_ident, "one"]] pry(main)> Ripper.lex(':alias') => [[[1, 0], :on_symbeg, ":"], [[1, 1], :on_kw, "alias"]]

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pry(main)> Ripper.lex('def alias(arg)')  => [[[1, 0], :on_kw, "def"],  [[1, 3], :on_sp, " "],  [[1, 4], :on_kw, "alias"],  [[1, 9], :on_lparen, "("],  [[1, 10], :on_ident, “arg"],  [[1, 13], :on_rparen, ")"]] pry(main)> Ripper.lex('def aliass(arg)')  => [[[1, 0], :on_kw, "def"],  [[1, 3], :on_sp, " "],  [[1, 4], :on_ident, "aliass"],  [[1, 10], :on_lparen, "("],  [[1, 11], :on_ident, "arg"],  [[1, 14], :on_rparen, ")"]]

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Which no one really considered problematic…

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Parser: A New Hope From Russia with Love

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parser is cross-platform

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well documented

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supports multiple parsing targets (Ruby 1.9 - 2.5)

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easy to work with ast format https://github.com/whitequark/ast

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p Parser::CurrentRuby.parse("2 + 2") # (send # (int 2) :+ # (int 2))

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AST node source location mappings

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p Parser::CurrentRuby.parse("2 + 2").loc # #, # @expression=#> p Parser::CurrentRuby.parse("2 + 2").loc.selector.source # "+"

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$ ruby-parse -L -e "2+2" (send (int 2) :+ (int 2)) 2+2 ~ selector ~~~ expression (int 2) 2+2 ~ expression (int 2) 2+2 ~ expression

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powerful code rewriting capabilities

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Struggles with Parser

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Parser was brand new

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Had no real users

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And had plenty of bugs…

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Peter Zotov (@whitequark)

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28th May, 2013 State of Unity

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RuboCop 0.8

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1st July, 2013 RuboCop 0.9

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Formatters

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Auto-correct

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Commissioner (single parsing run triggers all cops)

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Results caching (rubocop —-cache)

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Parallel Checks (rubocop —-parallel)

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Pattern Matching (regex-style matching for ast nodes)

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def on_send(node) receiver_node, method_name, *arg_nodes = *node return unless receiver_node && receiver_node.array_type? && method_name == :* && arg_nodes.first.str_type? add_offense(node, location: :selector) end Style/ArrayJoin (before)

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Style/ArrayJoin (now) def_node_matcher :join_candidate?, '(send $array :* $str)' def on_send(node) join_candidate?(node) { add_offense(node, location: :selector) } end

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RuboCop Today

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Started out with no conﬁguration at all…

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Today things are inﬁnitely conﬁgurable

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Metrics/LineLength: Enabled: false

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Metrics/LineLength: Max: 100

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Style/StringLiterals: Enabled: false

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Style/StringLiterals: EnforcedStyle: double_quotes

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You can set a target Ruby/Rails version

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You can limit cops to certain folders with Exclude/Include directives

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You can have different settings for the same cops in different directories

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You can inherit between conﬁguration ﬁles

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You can auto-generate an initial conﬁguration for your project

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rubocop —-auto-gen-config

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And you can read about all of this in RuboCop’s manual…

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rubocop.readthedocs.io

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gry is a smarter alternative to the built-in command https://github.com/pocke/gry

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RuboCop started as a code style checker

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•Style •Lint •Layout •Naming •Security •Performance •Performance •Rails •Bundler •Metric •Gemspec

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RuboCop is a great code formatter

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rubocop —-only Layout -a

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RuboCop does some linting better than ruby -w

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rubocop —-lint

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You can extend RuboCop with your own cops

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Granite (business actions architecture for Rails applications) https://toptal.github.io/granite/

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$ bundle exec rake new_cop[Department/Name]

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https://rubocop.readthedocs.io/ en/latest/development/

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class SimplifyNotEmptyWithAny < Cop MSG = 'Use `.any?` and remove the negation part.'.freeze def_node_matcher :not_empty_call?, <<-PATTERN (send (send (...) :empty?) :!) PATTERN def on_send(node) return unless not_empty_call?(node) add_offense(node) end end

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RuboCop has a rich ecosystem of extensions

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189!!!

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Notable Extensions • rubocop-rspec • guard-rubocop • rubocop-sequel • rubocop-cask

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Integration with code quality services •Code Climate •HoundCI •SideCI •Codacy

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RuboCop has integrations with many editors and IDEs

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Emacs 26.1 is out and it’s amazing!

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(spacemacs)

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The Road to RuboCop 1.0

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#1 question I get asked about RuboCop?

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When is RuboCop 1.0 coming?

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“Using RuboCop is exciting. You never know if —auto-correct is going to work or not!” — Dick Sutterer

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RuboCop changed my life! I used to go to horror movies to get an adrenaline rush - now I simply upgrade RuboCop! — Anton Devilov

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RuboCop’s learning curve is amazing! I’m still amazed it never ends! — Aaron Punisherson (@hardlove)

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“When faced with overwhelming odds just release 1.0 and it will all be OK!”

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Remove Rails (and maybe Performance) cops from RuboCop’s core

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Provide a proper (and stable) API for writing RuboCop extensions

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Introducing the brand new RuboCop HQ!

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https://github.com/bbatsov/rubocop

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https://github.com/rubocop-hq/rubocop

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RuboCop HQ •RuboCop •RuboCop JP •RuboCop RSpec/Rails/Performance •guard-rubocop, etc •Ruby & Rails Style Guides •Libraries extracted from RuboCop (e.g. node extensions, node pattern matching, etc)

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Review the conﬁg of all cops and come up with the best defaults

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Ideally each default should be backed by solid data/rationale

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Adjust the list of enabled by default cops

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Come up with a less painful process for dealing with new cops and conﬁguration changes

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mry makes RuboCop upgrades less painful https://github.com/pocke/mry

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Agree on what’s going to be constituting breaking changes down the road

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Breaking changes •Cop API changes •Extension API changes •Dropping support for Ruby versions •Renaming/removing cops •Renaming/changing/removing conﬁg values

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Cop status “New” in minor releases

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Cop status gets changed to Enabled/Disabled in major releases

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Extra Cop metadata •Version added •Version default conﬁg changed •Version deprecated

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eslint.org-grade manual/website

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RuboCop.org •Easy to navigate & mobile-friendly •Published using MkDocs (or similar) •Separate User and Developer manual •Getter getting started resources (e.g. video tutorials) •Improved cop documentation

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That’s a lot of work!

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Apes Together Strong!

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Rubyists Together Strong!

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Felina

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Thanks! twitter: @bbatsov github: @bbatsov http//batsov.com http://emacsredux.com Saint P RubyConf Saint Petersburg, Russia 10.06.2018