Add new Rails/HashLiteralKeysConversion cop

changelog/new_hash_literal_keys_conversion_cop.md

@@ -0,0 +1 @@
+* [#1332](https://github.com/rubocop/rubocop-rails/issues/1332): Add new `Rails/HashLiteralKeysConversion` cop. ([@fatkodima][])

config/default.yml

@@ -540,6 +540,11 @@ Rails/HasManyOrHasOneDependent:
   Include:
     - app/models/**/*.rb
 
+Rails/HashLiteralKeysConversion:
+  Description: 'Convert hash literal keys manually instead of using keys conversion methods.'
+  Enabled: pending
+  VersionAdded: '<<next>>'
+
 Rails/HelperInstanceVariable:
   Description: 'Do not use instance variables in helpers.'
   Enabled: true

lib/rubocop/cop/rails/hash_literal_keys_conversion.rb

@@ -0,0 +1,146 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # Detects when keys conversion methods are called on literal hashes, where it is redundant
+      # or keys can be manually converted to the required type.
+      #
+      # @example
+      #   # bad
+      #   { a: 1, b: 2 }.symbolize_keys
+      #
+      #   # bad
+      #   { a: 1, b: 2 }.stringify_keys
+      #
+      #   # good
+      #   { 'a' => 1, 'b' => 2 }
+      #
+      #   # good
+      #   { a: 1, var => 3 }.symbolize_keys
+      #
+      #   # good
+      #   { a:, b: 2 }.stringify_keys
+      #   { a: 1, b: foo }.deep_stringify_keys
+      #
+      class HashLiteralKeysConversion < Base
+        extend AutoCorrector
+
+        REDUNDANT_CONVERSION_MSG = 'Redundant hash keys conversion, all the keys have the required type.'
+        MSG = 'Convert hash keys explicitly to the required type.'
+
+        CONVERSION_METHODS = {
+          symbolize_keys: :sym,
+          symbolize_keys!: :sym,
+          stringify_keys: :str,
+          stringify_keys!: :str,
+          deep_symbolize_keys: :sym,
+          deep_symbolize_keys!: :sym,
+          deep_stringify_keys: :str,
+          deep_stringify_keys!: :str
+        }.freeze
+
+        RESTRICT_ON_SEND = CONVERSION_METHODS.keys
+
+        def on_send(node)
+          return unless (receiver = node.receiver)&.hash_type?
+
+          type = CONVERSION_METHODS[node.method_name]
+          deep = node.method_name.start_with?('deep_')
+          return unless convertible_hash?(receiver, deep: deep)
+
+          check(node, receiver, type: type, deep: deep)
+        end
+
+        # rubocop:disable Metrics/AbcSize
+        def check(node, hash_node, type: :sym, deep: false)
+          pair_nodes = pair_nodes(hash_node, deep: deep)
+
+          type_pairs, other_pairs = pair_nodes.partition { |pair_node| pair_node.key.type == type }
+
+          if type_pairs == pair_nodes
+            add_offense(node.loc.selector, message: REDUNDANT_CONVERSION_MSG) do |corrector|
+              corrector.remove(node.loc.dot)
+              corrector.remove(node.loc.selector)
+            end
+          else
+            add_offense(node.loc.selector) do |corrector|
+              corrector.remove(node.loc.dot)
+              corrector.remove(node.loc.selector)
+              autocorrect_hash_keys(other_pairs, type, corrector)
+            end
+          end
+        end
+        # rubocop:enable Metrics/AbcSize
+
+        private
+
+        def convertible_hash?(node, deep: false)
+          node.pairs.each do |pair|
+            return false unless convertible_key?(pair)
+            return false if deep && !convertible_node?(pair.value)
+          end
+
+          true
+        end
+
+        def convertible_key?(pair)
+          key, _value = *pair
+
+          (key.str_type? || key.sym_type?) && !pair.value_omission? && !key.value.match?(/\W/)
+        end
+
+        def convertible_array?(node)
+          node.values.all? do |value|
+            convertible_node?(value)
+          end
+        end
+
+        def convertible_node?(node)
+          if node.hash_type?
+            convertible_hash?(node)
+          elsif node.array_type?
+            convertible_array?(node)
+          else
+            node.literal?
+          end
+        end
+
+        def pair_nodes(hash_node, deep: false)
+          if deep
+            pair_nodes = []
+            do_pair_nodes(hash_node, pair_nodes)
+            pair_nodes
+          else
+            hash_node.pairs
+          end
+        end
+
+        def do_pair_nodes(node, pair_nodes)
+          if node.hash_type?
+            node.pairs.each do |pair_node|
+              pair_nodes << pair_node
+              do_pair_nodes(pair_node.value, pair_nodes)
+            end
+          elsif node.array_type?
+            node.each_value do |value|
+              do_pair_nodes(value, pair_nodes)
+            end
+          end
+        end
+
+        def autocorrect_hash_keys(pair_nodes, type, corrector)
+          pair_nodes.each do |pair_node|
+            if type == :sym
+              corrector.replace(pair_node.key, ":#{pair_node.key.value}")
+            else
+              corrector.replace(pair_node.key, "'#{pair_node.key.source}'")
+            end
+
+            corrector.replace(pair_node.loc.operator, '=>')
+          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_literal_keys_conversion'
 require_relative 'rails/helper_instance_variable'
 require_relative 'rails/http_positional_arguments'
 require_relative 'rails/http_status'