who/unix.rs: improve code coverage

[sylvestre]

https://app.codecov.io/gh/uutils/coreutils/blob/main/src%2Fuu%2Fwho%2Fsrc%2Fplatform%2Funix.rs

the code coverage can probably be improved easily here

[AnandajithS]

Hi, I would like to work on this issue. But I'm quite to new this, so I would appreciate some guidance on where to start

[cakebaker]

@AnandajithS I would probably start with a different issue ;-) Many of the existing who tests are disabled because of #3219 and so it might not be that easy to improve the coverage. I don't know whether @sylvestre took this into consideration when he opened the issue.

[AnandajithS]

Alright, thanks for the heads up

[ChrisDryden]

Have a fix to re-enable this in the CI here: #9442 it should be much easier now for someone new to add additional tests to cover specific features now if anyone is interested in adding more coverage