I think it depends on the language(s) your team(s) work with or would like to use. Have all of the reference docs and a dev environment setup on an offline lap

I think it depends on the language(s) your team(s) work with or would like to use. Have all of the reference docs and a dev environment setup on an offline laptop. Have an obviously toy problem inspired by real problems, yet clearly unrelated to anything your company plausibility needs solved. If it is common public knowledge that you already have a solution it might be fine to use a simplified version of that. Define solution criteria. Providing an interface and expecting an object that implements it correctly might be a good test for a go programmer.