Add new Lint/RedundantDirGlobSort cop

Sort globbed results by default in Ruby 3.0.
https://bugs.ruby-lang.org/issues/8709

This PR adds new `Lint/RedundantDirGlobSort` cop.
It checks for redundant `sort` method to `Dir.glob` and `Dir[]`.

```ruby
# bad
Dir.glob('./lib/**/*.rb').sort.each do |file|
end

Dir['./lib/**/*.rb'].sort.each do |file|
end

# good
Dir.glob('./lib/**/*.rb').each do |file|
end

Dir['./lib/**/*.rb'].each do |file|
end

# good - Respect intent if `sort` keyword option is specified.
Dir.glob('./lib/**/*.rb', sort: false).each do |file|
end
```

Related PR #9300.

changelog/new_add_new_lint_redundant_dir_glob_sort_cop.md

@@ -0,0 +1 @@
+* [#9301](https://github.com/rubocop-hq/rubocop/pull/9301): Add new `Lint/RedundantDirGlobSort` cop. ([@koic][])

config/default.yml

@@ -1835,6 +1835,11 @@ Lint/RedundantCopEnableDirective:
   Enabled: true
   VersionAdded: '0.76'
 
+Lint/RedundantDirGlobSort:
+  Description: 'Checks for redundant `sort` method to `Dir.glob` and `Dir[]`.'
+  Enabled: pending
+  VersionAdded: '<<next>>'
+
 Lint/RedundantRequireStatement:
   Description: 'Checks for unnecessary `require` statement.'
   Enabled: true

lib/rubocop.rb

@@ -318,6 +318,7 @@
 require_relative 'rubocop/cop/lint/rand_one'
 require_relative 'rubocop/cop/lint/redundant_cop_disable_directive'
 require_relative 'rubocop/cop/lint/redundant_cop_enable_directive'
+require_relative 'rubocop/cop/lint/redundant_dir_glob_sort'
 require_relative 'rubocop/cop/lint/redundant_require_statement'
 require_relative 'rubocop/cop/lint/redundant_safe_navigation'
 require_relative 'rubocop/cop/lint/redundant_splat_expansion'

lib/rubocop/cop/lint/redundant_dir_glob_sort.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Lint
+      # Sort globbed results by default in Ruby 3.0.
+      # This cop checks for redundant `sort` method to `Dir.glob` and `Dir[]`.
+      #
+      # @example
+      #
+      #   # bad
+      #   Dir.glob('./lib/**/*.rb').sort.each do |file|
+      #   end
+      #
+      #   Dir['./lib/**/*.rb'].sort.each do |file|
+      #   end
+      #
+      #   # good
+      #   Dir.glob('./lib/**/*.rb').each do |file|
+      #   end
+      #
+      #   Dir['./lib/**/*.rb'].each do |file|
+      #   end
+      #
+      class RedundantDirGlobSort < Base
+        extend AutoCorrector
+        extend TargetRubyVersion
+
+        minimum_target_ruby_version 3.0
+
+        MSG = 'Remove redundant `sort`.'
+        RESTRICT_ON_SEND = %i[sort].freeze
+        GLOB_METHODS = %i[glob []].freeze
+
+        def on_send(node)
+          return unless (receiver = node.receiver)
+          return unless receiver.receiver.const_type? && receiver.receiver.short_name == :Dir
+          return unless GLOB_METHODS.include?(receiver.method_name)
+
+          add_offense(node.loc.selector) do |corrector|
+            corrector.remove(node.loc.selector)
+            corrector.remove(node.loc.dot)
+          end
+        end
+      end
+    end
+  end
+end

spec/rubocop/cop/lint/redundant_dir_glob_sort_spec.rb

@@ -0,0 +1,98 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Lint::RedundantDirGlobSort, :config do
+  context 'when Ruby 3.0 or higher', :ruby30 do
+    it 'registers an offense and correction when using `Dir.glob.sort`' do
+      expect_offense(<<~RUBY)
+        Dir.glob(Rails.root.join('test', '*.rb')).sort.each(&method(:require))
+                                                  ^^^^ Remove redundant `sort`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        Dir.glob(Rails.root.join('test', '*.rb')).each(&method(:require))
+      RUBY
+    end
+
+    it 'registers an offense and correction when using `::Dir.glob.sort`' do
+      expect_offense(<<~RUBY)
+        ::Dir.glob(Rails.root.join('test', '*.rb')).sort.each(&method(:require))
+                                                    ^^^^ Remove redundant `sort`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        ::Dir.glob(Rails.root.join('test', '*.rb')).each(&method(:require))
+      RUBY
+    end
+
+    it 'registers an offense and correction when using `Dir[].sort.each do`' do
+      expect_offense(<<~RUBY)
+        Dir['./lib/**/*.rb'].sort.each do |file|
+                             ^^^^ Remove redundant `sort`.
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        Dir['./lib/**/*.rb'].each do |file|
+        end
+      RUBY
+    end
+
+    it 'registers an offense and correction when using `Dir[].sort.each(&do_something)`' do
+      expect_offense(<<~RUBY)
+        Dir['./lib/**/*.rb'].sort.each(&method(:require))
+                             ^^^^ Remove redundant `sort`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        Dir['./lib/**/*.rb'].each(&method(:require))
+      RUBY
+    end
+
+    it 'does not register an offense when not using `sort` with `sort: false` option for `Dir`' do
+      expect_no_offenses(<<~RUBY)
+        Dir.glob(Rails.root.join('test', '*.rb'), sort: false).each do
+        end
+      RUBY
+    end
+  end
+
+  context 'when Ruby 2.7 or lower', :ruby27 do
+    it 'does not register an offense and correction when using `Dir.glob.sort`' do
+      expect_no_offenses(<<~RUBY)
+        Dir.glob(Rails.root.join('test', '*.rb')).sort.each(&method(:require))
+      RUBY
+    end
+
+    it 'does not register an offense and correction when using `::Dir.glob.sort`' do
+      expect_no_offenses(<<~RUBY)
+        ::Dir.glob(Rails.root.join('test', '*.rb')).sort.each(&method(:require))
+      RUBY
+    end
+
+    it 'does not register an offense and correction when using `Dir[].sort.each do`' do
+      expect_no_offenses(<<~RUBY)
+        Dir['./lib/**/*.rb'].sort.each do |file|
+        end
+      RUBY
+    end
+
+    it 'does not register an offense and correction when using `Dir[].sort.each(&do_something)`' do
+      expect_no_offenses(<<~RUBY)
+        Dir['./lib/**/*.rb'].sort.each(&method(:require))
+      RUBY
+    end
+  end
+
+  it 'does not register an offense when not using `sort` for `Dir`' do
+    expect_no_offenses(<<~RUBY)
+      Dir['./lib/**/*.rb'].each do |file|
+      end
+    RUBY
+  end
+
+  it 'does not register an offense when using `sort` without a receiver' do
+    expect_no_offenses(<<~RUBY)
+      sort.do_something
+    RUBY
+  end
+end