Quality assurance and test plans don't catch slop. They just test your code. It can't prove the absence of bugs.
In general, the way we still do it is: some basic static analysis finding anti-patterns, but the meat of it is, and always will be, code review. Except you can't review code at the pace AI generates it.
Where I work someone is still responsible for the output. We expect developers to examine the code the LLM produces before burdening someone else with it.