Make it possible to set StyleGuideBaseURL per department

[koic]

Summary

Resolves rubocop/rubocop-rails#107 and follow up rubocop/rubocop-rails#109 (comment).

This PR makes it possible to set a style guide URL (StyleGuideBaseURL) for each department.

For example, RuboCop Rails gem (Rails department) supports The Rails Style Guide. In that case, set .rubocop.yml as follows.

# .rubocop.yml
require:
  - rubocop-rails

AllCops:
  StyleGuideBaseURL:  https://rubystyle.guide

Rails:
  StyleGuideBaseURL:  https://rails.rubystyle.guide

In practice Rails: StyleGuideBaseURL: https://rails.rubystyle.guide will be set in config/default.yml of rubocop-rails.

% cat example.rb
# frozen_string_literal: true

time = Time.new

% bundle exec rubocop --display-style-guide example.rb
Inspecting 1 file
W

Offenses:

example.rb:3:1: W: Lint/UselessAssignment: Useless assignment to
variable - time. (https://rubystyle.guide#underscore-unused-vars)
time = Time.new
^^^^
example.rb:3:13: C: Rails/TimeZone: Do not use Time.new without
zone. Use one of Time.zone.now, Time.current, Time.new.in_time_zone,
Time.new.utc, Time.new.getlocal, Time.new.xmlschema, Time.new.iso8601,
Time.new.jisx0301, Time.new.rfc3339, Time.new.httpdate, Time.new.to_i,
Time.new.to_f instead. (https://rails.rubystyle.guide#time,
http://danilenko.org/2012/7/6/rails_timezones)
time = Time.new
            ^^^

1 file inspected, 2 offenses detected

The style guide URLs set for each department is displayed.

• https://rubystyle.guide#underscore-unused-vars for Lint/UselessAssignment cop
• https://rails.rubystyle.guide#time for for Rails/TimeZone cop

So AllCops style guide URL is used when there is no style guide URL for a specific department.

Other Information

Note that tasks/cops_documentation.rake will require the following patch:

diff --git a/tasks/cops_documentation.rake
b/tasks/cops_documentation.rake
index bd93ffe31..751222fcb 100644
--- a/tasks/cops_documentation.rake
+++ b/tasks/cops_documentation.rake
@@ -155,7 +155,9 @@ task generate_cops_documentation:
:yard_for_generate_documentation do

   def references(config, cop)
     cop_config = config.for_cop(cop)
-    urls = RuboCop::Cop::MessageAnnotator.new(config, cop_config, {}).urls
+    urls = RuboCop::Cop::MessageAnnotator.new(
+      config, cop.name, cop_config, {}
+    ).urls
     return '' if urls.empty?

     content = h3('References')

AFAIK, rubocop-performance, rubocop-rails, rubocop-rspec, and rubocop-minitest repositories are targeted.

/cc @bquorning

---

Before submitting the PR make sure the following are checked:

• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

[bbatsov]

I like that approach, but I think we should also mention it somewhere in the documentation.

[bbatsov]

I think calling this a plugin might be a bit misleading - something like "Make it possible to set StyleGuideBaseURL per department." sounds better to me.

[koic]

Thanks for your review. I update it.

[koic]

I tried adding a document about this.
d5f1483

[bbatsov]

Great work! Thanks!