Add Rails/TopLevelHashWithIndifferentAccess cop

changelog/new_add_rails_top_level_hash_with_indifferent_access.md

@@ -0,0 +1 @@
+* [#752](https://github.com/rubocop/rubocop-rails/pull/752): Add `Rails/TopLevelHashWithIndifferentAccess` cop. ([@r7kamura][])

config/default.yml

@@ -958,6 +958,12 @@ Rails/ToSWithArgument:
   Safe: false
   VersionAdded: '<<next>>'
 
+Rails/TopLevelHashWithIndifferentAccess:
+  Description: 'Identifies top-level `HashWithIndifferentAccess`.'
+  Reference: 'https://guides.rubyonrails.org/upgrading_ruby_on_rails.html#top-level-hashwithindifferentaccess-is-soft-deprecated'
+  Enabled: pending
+  VersionAdded: '<<next>>'
+
 Rails/TransactionExitStatement:
   Description: 'Avoid the usage of `return`, `break` and `throw` in transaction blocks.'
   Enabled: pending

lib/rubocop/cop/rails/top_level_hash_with_indifferent_access.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # Identifies top-level `HashWithIndifferentAccess`.
+      # This has been soft-deprecated since Rails 5.1.
+      #
+      # @example
+      #   # bad
+      #   HashWithIndifferentAccess.new(foo: 'bar')
+      #
+      #   # good
+      #   ActiveSupport::HashWithIndifferentAccess.new(foo: 'bar')
+      #
+      class TopLevelHashWithIndifferentAccess < Base
+        extend AutoCorrector
+        extend TargetRailsVersion
+
+        minimum_target_rails_version 5.1
+
+        MSG = 'Avoid top-level `HashWithIndifferentAccess`.'
+
+        # @!method top_level_hash_with_indifferent_access?(node)
+        #   @param [RuboCop::AST::ConstNode] node
+        #   @return [Boolean]
+        def_node_matcher :top_level_hash_with_indifferent_access?, <<~PATTERN
+          (const {nil? cbase} :HashWithIndifferentAccess)
+        PATTERN
+
+        # @param [RuboCop::AST::ConstNode] node
+        def on_const(node)
+          return unless top_level_hash_with_indifferent_access?(node)
+
+          add_offense(node) do |corrector|
+            autocorrect(corrector, node)
+          end
+        end
+
+        private
+
+        def autocorrect(corrector, node)
+          corrector.insert_before(node.location.name, 'ActiveSupport::')
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rails_cops.rb

@@ -114,6 +114,7 @@
 require_relative 'rails/time_zone_assignment'
 require_relative 'rails/to_formatted_s'
 require_relative 'rails/to_s_with_argument'
+require_relative 'rails/top_level_hash_with_indifferent_access'
 require_relative 'rails/transaction_exit_statement'
 require_relative 'rails/uniq_before_pluck'
 require_relative 'rails/unique_validation_without_index'

spec/rubocop/cop/rails/top_level_hash_with_indifferent_access_spec.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rails::TopLevelHashWithIndifferentAccess, :config, :rails51 do
+  context 'with top-level HashWithIndifferentAccess' do
+    it 'registers and corrects an offense' do
+      expect_offense(<<~RUBY)
+        HashWithIndifferentAccess.new(foo: 'bar')
+        ^^^^^^^^^^^^^^^^^^^^^^^^^ Avoid top-level `HashWithIndifferentAccess`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        ActiveSupport::HashWithIndifferentAccess.new(foo: 'bar')
+      RUBY
+    end
+  end
+
+  context 'with top-level ::HashWithIndifferentAccess' do
+    it 'registers and corrects an offense' do
+      expect_offense(<<~RUBY)
+        ::HashWithIndifferentAccess.new(foo: 'bar')
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Avoid top-level `HashWithIndifferentAccess`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        ::ActiveSupport::HashWithIndifferentAccess.new(foo: 'bar')
+      RUBY
+    end
+  end
+
+  context 'with ActiveSupport::HashWithIndifferentAccess' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        ActiveSupport::HashWithIndifferentAccess.new(foo: 'bar')
+      RUBY
+    end
+  end
+
+  context 'with ActiveSupport::HashWithIndifferentAccess on Rails 5.0', :rails50 do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        HashWithIndifferentAccess.new(foo: 'bar')
+      RUBY
+    end
+  end
+end