Ken
You do it and get the job?
We could not agree on the value of my services.
Test was pretty easy, no issue there. We could not agree on the value of my services.
But they got a free program wrote for their machine
I had an "interview" for a maintenance tech position back in the early 2000's.
As a 'test' the owner had me look at a down machine to determine the cause and see if my answer 'concurred' with what his guy found. Quickly figured out he didn't have a 'guy' and wanted a free diagnosis. I told him that when I was hired I would fix it, otherwise my consulting fee was $300 per hour.
Test was pretty easy, no issue there. We could not agree on the value of my services.
The purpose of them giving you a task to make a program is to test your experience and how well you approach a task with little time to think about it. It would not be in their best interest to give you info before the interview. If they have to give you the answer now and you get hired, then they will most likely have to give you the answers later, as well.
Just go to the interview and give it your best shot. If you are the best person available, then you will get offered a position. If they see you struggle a bit, you may still get an offer, but they may add some training to your objectives so both you and the company benefit.