[Fix rubocop#838] Fix an incorrect autocorrect for Rails/ActionOrder

Fixes rubocop#838.

This PR fixes an incorrect autocorrect for `Rails/ActionOrder`
when using unconventional order of actions in conditions.

Author: koic

changelog/fix_an_incorrect_autocorrect_for_rails_action_order.md

@@ -0,0 +1 @@
+* [#838](https://github.com/rubocop/rubocop-rails/issues/838): Fix an incorrect autocorrect for `Rails/ActionOrder` when using unconventional order of actions in conditions. ([@koic][])

lib/rubocop/cop/rails/action_order.rb

@@ -71,10 +71,17 @@ def register_offense(previous, current)
             current: current.method_name
           )
           add_offense(current, message: message) do |corrector|
+            current = correction_target(current)
+            previous = correction_target(previous)
+
             corrector.replace(current, previous.source)
             corrector.replace(previous, current.source)
           end
         end
+
+        def correction_target(def_node)
+          def_node.each_ancestor(:if).first || def_node
+        end
       end
     end
   end

spec/rubocop/cop/rails/action_order_spec.rb

@@ -115,6 +115,37 @@ def show; end
     RUBY
   end
 
+  it 'detects unconventional order of actions in conditions' do
+    expect_offense(<<~RUBY)
+      class TestController < BaseController
+        unless Rails.env.development?
+          def edit
+          end
+        end
+
+        if Rails.env.development?
+          def index
+          ^^^^^^^^^ Action `index` should appear before `edit`.
+          end
+        end
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      class TestController < BaseController
+        if Rails.env.development?
+          def index
+          end
+        end
+
+        unless Rails.env.development?
+          def edit
+          end
+        end
+      end
+    RUBY
+  end
+
   context 'with custom ordering' do
     it 'enforces custom order' do
       cop_config['ExpectedOrder'] = %w[show index new edit create update destroy]