The duration should be hours, not days. The way I've done it in the past is by pre-arranging with the candidate a time that they'd like to do the test (maybe 7p

The duration should be hours, not days. The way I've done it in the past is by pre-arranging with the candidate a time that they'd like to do the test (maybe 7pm on a Tuesday, or 3pm on a Saturday). They're sent some details of the development environment and guidance before hand. Then they're sent the test at that time and then have to send the result back within 3 hours. I suppose that still selects for people who have 3 contiguous hours to spare. But it feels to me to be the fairest solution - it doesn't reward people who have endless time, and it doesn't subject poor candidates to open ended misery. Sending the dev environment stuff before hand gives them time to make sure it's working first - and an opportunity to ask questions about the environment if anything is unclear. It definitely shouldn't take 2 hours to set up a development environment - if that's the case then it's either an inexperienced candidate or very poor instructions.