[Issue rubocop#1269] Add tests for `Rails/ActionControllerFlashBefore…

…Render` from issue rubocop#1269

This cop would need to do control flow analysis which it just doesn't do. RuboCop also has no mechanism for that.

So just reverting this for now to fix the newly introduces false positives

changelog/fix_revert_flash_before_render.md

@@ -0,0 +1 @@
+* [#1269](https://github.com/rubocop/rubocop-rails/issues/1269): Fix positives for `Rails/ActionControllerFlashBeforeRender` in combination with implicit returns. ([@earlopain][])

spec/rubocop/cop/rails/action_controller_flash_before_render_spec.rb

@@ -328,4 +328,71 @@ def create
       RUBY
     end
   end
+
+  context 'when using `flash` after `render` and `redirect_to` is used in implicit return branch ' \
+          'and render is is used in the other branch' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        class HomeController < ApplicationController
+          def create
+            if foo.update(params)
+              flash[:success] = 'msg'
+
+              if redirect_to_index?
+                redirect_to index
+              else
+                redirect_to path(foo)
+              end
+            else
+              flash.now[:alert] = 'msg'
+              render :edit, status: :unprocessable_entity
+            end
+          end
+        end
+      RUBY
+    end
+  end
+
+  context 'when using `flash` after `render` and `render` is part of a different preceeding branch' \
+          'that implicitly returns' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        class HomeController < ApplicationController
+          def create
+            if remote_request? || sandbox?
+              if current_user.nil?
+                render :index
+              else
+                head :forbidden
+              end
+            elsif current_user.nil?
+              redirect_to sign_in_path
+            else
+              flash[:alert] = 'msg'
+              if request.referer.present?
+                redirect_to(request.referer)
+              else
+                redirect_to(root_path)
+              end
+            end
+          end
+        end
+      RUBY
+    end
+  end
+
+  context 'when using `flash` in `rescue` and `redirect_to` in `ensure`' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        class HomeController < ApplicationController
+          def create
+          rescue
+            flash[:alert] = 'msg'
+          ensure
+            redirect_to :index
+          end
+        end
+      RUBY
+    end
+  end
 end