"Proper" may be doing some work here, but such a test was run last year and GPT-4.5 and LLaMa-3.1-405B both passed. Oddly, GPT-4.5 was judged as human significantly more often than chance. https://arxiv.org/abs/2503.23674

Dude, you're in a Turing test right now. Conservatively, 10% of comments on this site are LLM output. We're all conversing with robots.