I would throw some buckets of water through it to test.
I'm guessing it will be fine.
I am remodelling my basement. When the house was built in the 1950s a rough-in was installed for a shower, toilet and vanity in the basement.
The shower and vanity rough-ins were capped when I bought the house but the cap on the toilet rough-in was smashed. It did not smell, but I capped it anyway and forgot about it.
But now I am starting to wonder whether these rough-ins actually work. The one I am particularly worried about is the toilet one which did not smell and had a smashed cap.
Is the test to throw several buckets of water down it?