[Fix #1244] Fix a false positive for Rails/ActionControllerFlashBeforeRender when returning redirect_to

changelog/fix_a_false_positive_for_rails_action_controller_flash_before_render.md

@@ -0,0 +1 @@
+* [#1244](https://github.com/rubocop/rubocop-rails/issues/1244): Fix a false positive for `Rails/ActionControllerFlashBeforeRender` when returning `redirect_to`. ([@earlopain][])

lib/rubocop/cop/rails/action_controller_flash_before_render.rb

@@ -99,6 +99,8 @@ def instance_method_or_block?(node)
 
         def use_redirect_to?(context)
           context.right_siblings.compact.any? do |sibling|
+            # Unwrap `return redirect_to :index`
+            sibling = sibling.children.first if sibling.return_type? && sibling.children.one?
             sibling.send_type? && sibling.method?(:redirect_to)
           end
         end

spec/rubocop/cop/rails/action_controller_flash_before_render_spec.rb

@@ -312,4 +312,20 @@ def create
       RUBY
     end
   end
+
+  context 'when using `flash` after `render` and returning `redirect_to` in condition block' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        class HomeController < ApplicationController
+          def create
+            if condition
+              flash[:alert] = "msg"
+              return redirect_to "https://www.example.com/"
+            end
+            render :index
+          end
+        end
+      RUBY
+    end
+  end
 end