> If a company really wants to test someone's programming ability in an interview, I feel like the best thing to do would be to make up a programming language, give them a reference sheet, and then ask them to program a couple different versions of fizz-bizz.
Are you joking? Doing fizz-buzz is way too low of a bar. That doesn't even show you can use standard classes and things, like maps and lists.
> but I think you'd at least be testing the skills people actually use when programming
That would tests very few of them, unfortunately.
> rather than whether they can remember every bit of syntax from every language they have listed on their resume
No one I see tests for syntax, but for the more important/broader concepts.
> if I lied and said I knew javascript, I'd almost certainly fail a programming test that used a made-up language based on it.
Probably not. Most mainstream languages have pretty similar syntax. And if you expected people to know others without warning, people would raise hell. Anyone who knows C can probably guess the gist of what a small snippet of non-tricky Javascript does.