It's not rare for me to ask if they tested it. They can lie, but if they say they did and it crashes on me right when I start it, then I may never trust this contributor ever again.
Also I don't hesitate to be frank in my review, it's okay to say "I won't merge your feature because I don't think I can maintain that, but you're free to keep your fork". Or "I can merge it if you change this and this", but in that case I need to actually merge if they do what I asked for.
> They can lie, but if they say they did and it crashes on me right when I start it, then I may never trust this contributor ever again.
If it’s obvious without a shadow of a doubt that someone has lied, either on an issue or a PR, I’m very much inclined to block them. I have a lot of patience for people who are still learning or make silly mistakes but are genuinely making an effort; but if someone doesn’t even help me help them, that’s disrespectful and such behaviour shouldn’t be rewarded.