This is easy for me --- I rat them out. Whether or not I signed an honor code.

On a test? If how they do on the test impacts me (like the test is graded on a curve), I rat them out. Otherwise, I keep mum. That is my honest, and probably terrible, answer.

Unless I'm administering the test, I do nothing. Karma will get them in the end.

Actually, that's more like what I tell myself, but more and more I realise people that cheat in life end up winning. Still, not my place to interfere.

I don't know what an 'honour code' is, but it sounds very American.

Yup, I think "honor code" is an American thing.

I'd probably ignore it. I might drop an anonymous note in the instructor's bin, but that's about as far as I'll go. Unless I had just come out of Marine boot camp and could defend myself effectively against any reprisals, then I might turn rat. Otherwise, I look the other way.

Context! Need context. I like these questions but time is teaching me that so much about these ethics is really situational. I'm not comfortable with a flat yes/no. I need to know what, who, when, why, what I know, what they know, what the context is, what's at stake.

Meh, if they wanna be cheating jackasses, that's their problem.

This is a regular problem for me as a teacher. I don't report them as they will be thrown out of school. These are students from a ghetto environment and might be the first in their family to go to college.

Practically speaking, those who cheat don't know who to copy from and invariably choose the wrong person so they tend to fail.

I also tell them that their goal on the exam is to convince me that they know what they're doing and the right answer is a minor part of that. If their right answer isn't properly supported, I give no credit. Sometimes I make them do the problem on the board afterwards. Cheaters are unable to do this. If somehow they learned enough to do it since then, they deserve the credit.