I've always wanted to interview someone by giving them some code, and saying "please add such-and-such a feature." I've had interviews before where people have

I've always wanted to interview someone by giving them some code, and saying "please add such-and-such a feature." I've had interviews before where people have given me code on paper and asked me to critique it; also gave me a program where they'd introduced a bug, and asked me to find the bug. It's a shame these things haven't caught on. Developing green field code is only a tiny fraction of what we do.