Pluginfy RuboCop Rake

This PR makes RuboCop Rake support RuboCop's Plugin feature.

It replaces the ad-hoc `Inject` with RuboCop plugins introduced in RuboCop 1.72.
Additionally, since RuboCop already requires Ruby 2.7 or higher as its runtime,
the `required_ruby_version` will be updated to 2.7.

Follow-up rubocop/rubocop#13792

.rubocop.yml

@@ -1,8 +1,10 @@
 inherit_from: .rubocop_todo.yml
 
-require:
-  - rubocop/cop/internal_affairs
+plugins:
+  - rubocop-internal_affairs
   - rubocop-rake
+
+require:
   - rubocop-rspec
 
 AllCops:

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## master (unreleased)
 
+* [#58](https://github.com/rubocop/rubocop-rake/pull/58): Pluginfy RuboCop Rake. ([@koic][])
 * [#57](https://github.com/rubocop/rubocop-rake/pull/57): Drop support Ruby 2.5 and 2.6 for runtime environment. ([@koic][])
 
 ## 0.6.0 (2021-06-29)

Gemfile

@@ -7,5 +7,5 @@ gemspec
 
 gem "rake", "~> 13.0"
 gem 'rspec'
-gem 'rubocop', '>= 0.76'
+gem 'rubocop', '>= 1.72.1'
 gem 'rubocop-rspec'

README.md

@@ -31,24 +31,27 @@ ways to do this:
 Put this into your `.rubocop.yml`.
 
 ```yaml
-require: rubocop-rake
+plugins: rubocop-rake
 ```
 
 Alternatively, use the following array notation when specifying multiple extensions.
 
 ```yaml
-require:
+plugins:
   - rubocop-other-extension
   - rubocop-rake
 ```
 
 Now you can run `rubocop` and it will automatically load the RuboCop Rake
 cops together with the standard cops.
 
+> [!NOTE]
+> The plugin system is supported in RuboCop 1.72+. In earlier versions, use `require` instead of `plugins`.
+
 ### Command line
 
 ```bash
-rubocop --require rubocop-rake
+rubocop --plugin rubocop-rake
 ```
 
 ### Rake task
@@ -57,7 +60,7 @@ rubocop --require rubocop-rake
 require 'rubocop/rake_task'
 
 RuboCop::RakeTask.new do |task|
-  task.requires << 'rubocop-rake'
+  task.plugins << 'rubocop-rake'
 end
 ```
 
@@ -71,4 +74,3 @@ To install this gem onto your local machine, run `bundle exec rake install`. To
 ## Contributing
 
 Bug reports and pull requests are welcome on GitHub at https://github.com/rubocop/rubocop-rake.
-

lib/rubocop-rake.rb

@@ -4,9 +4,7 @@
 
 require_relative 'rubocop/rake'
 require_relative 'rubocop/rake/version'
-require_relative 'rubocop/rake/inject'
-
-RuboCop::Rake::Inject.defaults!
+require_relative 'rubocop/rake/plugin'
 
 require_relative 'rubocop/cop/rake/helper/class_definition'
 require_relative 'rubocop/cop/rake/helper/on_task'

lib/rubocop/rake.rb

@@ -6,11 +6,5 @@ module RuboCop
   # :nodoc:
   module Rake
     class Error < StandardError; end
-
-    PROJECT_ROOT   = Pathname.new(__dir__).parent.parent.expand_path.freeze
-    CONFIG_DEFAULT = PROJECT_ROOT.join('config', 'default.yml').freeze
-    CONFIG         = YAML.safe_load(CONFIG_DEFAULT.read).freeze
-
-    private_constant(:CONFIG_DEFAULT, :PROJECT_ROOT)
   end
 end

lib/rubocop/rake/plugin.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require 'lint_roller'
+
+module RuboCop
+  module Rake
+    # A plugin that integrates RuboCop Rake with RuboCop's plugin system.
+    class Plugin < LintRoller::Plugin
+      def about
+        LintRoller::About.new(
+          name: 'rubocop-rake',
+          version: Version::STRING,
+          homepage: 'https://github.com/rubocop/rubocop-rake',
+          description: 'A RuboCop plugin for Rake.',
+        )
+      end
+
+      def supported?(context)
+        context.engine == :rubocop
+      end
+
+      def rules(_context)
+        LintRoller::Rules.new(
+          type: :path,
+          config_format: :rubocop,
+          value: Pathname.new(__dir__).join('../../../config/default.yml'),
+        )
+      end
+    end
+  end
+end

rubocop-rake.gemspec

@@ -19,7 +19,8 @@ Gem::Specification.new do |spec|
     'homepage_uri' => spec.homepage,
     'source_code_uri' => spec.homepage,
     'changelog_uri' => "https://github.com/rubocop/rubocop-rake/blob/master/CHANGELOG.md",
-    'rubygems_mfa_required' => 'true'
+    'rubygems_mfa_required' => 'true',
+    'default_lint_roller_plugin' => 'RuboCop::Rake::Plugin'
   }
 
   # Specify which files should be added to the gem when it is released.
@@ -31,5 +32,6 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency 'rubocop', '~> 1.0'
+  spec.add_dependency 'lint_roller', '~> 1.1'
+  spec.add_dependency 'rubocop', '>= 1.72.1'
 end

spec/spec_helper.rb

@@ -4,8 +4,6 @@
 require 'rubocop/rspec/support'
 
 RSpec.configure do |config|
-  config.include RuboCop::RSpec::ExpectOffense
-
   config.disable_monkey_patching!
   config.raise_errors_for_deprecations!
   config.raise_on_warning = true