Add Rails/HashKeyValueRoute cop

changelog/new_add_rails_hash_key_value_route_cop.md

@@ -0,0 +1 @@
+* [#1329](https://github.com/rubocop/rubocop-rails/pull/1329): Add `Rails/HashKeyValueRoute` cop. ([@r7kamura][])

config/default.yml

@@ -540,6 +540,15 @@ Rails/HasManyOrHasOneDependent:
   Include:
     - app/models/**/*.rb
 
+Rails/HashKeyValueRoute:
+  Description: 'Avoid Hash key-value routing.'
+  Enabled: pending
+  Safe: false
+  VersionAdded: '<<next>>'
+  Include:
+    - config/routes.rb
+    - config/routes/**/*.rb
+
 Rails/HelperInstanceVariable:
   Description: 'Do not use instance variables in helpers.'
   Enabled: true

lib/rubocop/cop/rails/hash_key_value_route.rb

@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # Avoid Hash key-value routing.
+      # Drawing a route in this style will be removed in Rails 8.1.
+      #
+      # @safety
+      #   This cop is unsafe because it is implemented on the assumption that
+      #   the first element of Hash always contains path and endpoint, based on
+      #   the background that it is often so written.
+      #
+      # @example
+      #   # bad
+      #   get '/users' => 'users#index'
+      #
+      #   # good
+      #   get '/users', to: 'users#index'
+      #
+      #   # bad
+      #   mount MyApp => '/my_app'
+      #
+      #   # good
+      #   mount MyApp, at: '/my_app'
+      class HashKeyValueRoute < Base
+        extend AutoCorrector
+
+        MSG = 'Avoid Hash key-value routing.'
+
+        RESTRICT_ON_SEND = %i[delete get match mount options patch post put].freeze
+
+        # @!method hash_key_value_route(node)
+        def_node_matcher :hash_key_value_route, <<~PATTERN
+          (send
+            nil?
+            _
+            (hash
+              $(pair $_ $_)
+              ...
+            )
+          )
+        PATTERN
+
+        def on_send(node)
+          hash_key_value_route(node) do |pair, key, value|
+            add_offense(pair) do |corrector|
+              corrector.replace(pair, "#{key.source}, #{option_name(node)}: #{value.source}")
+            end
+          end
+        end
+
+        private
+
+        def option_name(node)
+          if node.method?(:mount)
+            'at'
+          else
+            'to'
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rails_cops.rb

@@ -59,6 +59,7 @@
 require_relative 'rails/freeze_time'
 require_relative 'rails/has_and_belongs_to_many'
 require_relative 'rails/has_many_or_has_one_dependent'
+require_relative 'rails/hash_key_value_route'
 require_relative 'rails/helper_instance_variable'
 require_relative 'rails/http_positional_arguments'
 require_relative 'rails/http_status'

spec/rubocop/cop/rails/hash_key_value_route_spec.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rails::HashKeyValueRoute, :config do
+  context 'when using hash key-value route' do
+    it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        get '/foos' => 'foos#index'
+            ^^^^^^^^^^^^^^^^^^^^^^^ Avoid Hash key-value routing.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        get '/foos', to: 'foos#index'
+      RUBY
+    end
+  end
+
+  context 'with other options' do
+    it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        get '/foos' => 'foos#index', as: 'foos'
+            ^^^^^^^^^^^^^^^^^^^^^^^ Avoid Hash key-value routing.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        get '/foos', to: 'foos#index', as: 'foos'
+      RUBY
+    end
+  end
+
+  context 'with `mount`' do
+    it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        mount MyApp => '/my_app'
+              ^^^^^^^^^^^^^^^^^^ Avoid Hash key-value routing.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        mount MyApp, at: '/my_app'
+      RUBY
+    end
+  end
+
+  context 'without hash key-value route' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        get '/foos', to: 'foos#index'
+      RUBY
+    end
+  end
+end