fixes #3704

app/controllers/moderator/post/posts_controller.rb

@@ -21,7 +21,7 @@ module Moderator
 
       def undelete
         @post = ::Post.find(params[:id])
-        @post.undelete!
+        @post.approve!
       end
 
       def confirm_move_favorites

test/functional/moderator/post/posts_controller_test.rb

@@ -42,7 +42,9 @@ module Moderator
             as_user do
               @post.update(is_deleted: true)
             end
-            post_auth undelete_moderator_post_post_path(@post), @admin, params: {:format => "js"}
+            assert_difference(-> { PostApproval.count }, 1) do
+              post_auth undelete_moderator_post_post_path(@post), @admin, params: {:format => "js"}
+            end
 
             assert_response :success
             assert(!@post.reload.is_deleted?)