[Fix rubocop#78] Autocorrect HashEnum Cop

lib/rubocop/cop/rails/hash_enum.rb

@@ -25,6 +25,34 @@ def on_send(node)
             add_offense(node, message: format(MSG, enum: name))
           end
         end
+
+        def autocorrect(node)
+          enum_values = node.children[2].children.first.children[1]
+          to_replace = enum_values.loc.expression
+          values_hash = "{ #{converted_values(enum_values)} }"
+
+          ->(corrector) { corrector.replace(to_replace, values_hash) }
+        end
+
+        private
+
+        def converted_values(enum_values)
+          enum_values.children.each_with_index.map do |child, index|
+            hash_entry_as_string(child, index)
+          end.join(', ')
+        end
+
+        def hash_entry_as_string(child, index)
+          value = child.children.first
+          case value
+          when String
+            "'#{value}' => #{index}"
+          when Symbol
+            "#{value}: #{index}"
+          else
+            "#{child.source} => #{index}"
+          end
+        end
       end
     end
   end

manual/cops_rails.md

@@ -900,7 +900,7 @@ Include | `app/models/**/*.rb` | Array
 
 Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
 --- | --- | --- | --- | ---
-Enabled | Yes | No | 0.74 | -
+Enabled | Yes | Yes  | 0.74 | -
 
 This cop looks for enums written with array syntax
 

spec/rubocop/cop/rails/hash_enum_spec.rb

@@ -50,6 +50,12 @@
         RUBY
       end
     end
+
+    it 'autocorrects' do
+      expect(
+        autocorrect_source('enum status: [:active, "completely archived", 42]')
+      ).to eq("enum status: { active: 0, 'completely archived' => 1, 42 => 2 }")
+    end
   end
 
   context 'when hash syntax is used' do