I also have to agree to the input from NateLane, RandomStroke and Torbach.
According to NateLane, compensation would be great. If you have multiple jobs or student loans, it is difficult to work for free. If you are unemployed (layoffs, releases, etc.), it is very difficult to spend as much time (most likely to do multiple art tests and interviews) while your savings burn out and stacks of bills. If you are trying to leave a job for a better studio but have children, I could imagine that it is difficult to work on something in your free time and not with the family just to show nothing.
According to Torbach, art tests absolutely feel like you're setting up everything for potentially nothing. In almost every art test I did, I had to submit not only the video of the effect, but also all of the textures and meshes I created for it, and sometimes even my shaders or a breakdown and explanation of my shaders. The agreement for the art test always included the language that whatever I do for the art test, regardless of a job offer, becomes the property of this company … Really? If I'm already working for free, do I have to give you everything I've done now? If you don't just look at my effect and know exactly what material tricks I'm doing it with, then it seems I have a value that I should be hired to find out what my secret sauce is. I find myself providing small thumbnails of my textures, but to give up the full-size texture assets I've spent time for free? That takes a little bit imo. They also ask candidates to constantly reinvent the wheel, which takes time.
This type fits what RandomStroke mentioned: No NDA. I can understand that I didn't reveal the request that the studio gave you for the test. I don't want people to cheat the system and schedule an art test. But if a studio doesn't provide the material / shader, textures, nets, etc., you shouldn't claim what we use in our art test when we make it ourselves.
I like Torbach's idea that the studio provides the assets and sees how the artist uses them. In addition, many people spend most of their time doing art in their workplace, and they may not have all the infrastructure at home to dive their feet first and start creating on the first day.