[Animats]

No, that's not how it's done. Proper testing for computer usability involves video of the user and the screen. The important things to note are when the user stops, gets stuck, has to consult external references, asks for help, or gets upset. It's far too intrusive to impose on anyone not explicitly volunteering to do it.

[spangry]

Unfortunately I have but only one upvote to give. This is very important if you're performing a usability / ergonomics study. Context matters a great deal. The parent poster is also quite correct about it being invasive: although not absolutely necessary, ideally you'd observe the user in whatever context they happen to use Rust (e.g. at their workplace or in their home). Lab studies are still valuable too, but you might miss some context due to the artificial setting.