My darkroom has a few light leaks, mainly around the door. I've proven it's safe for paper by putting a coin on paper, leaving it for 15 mins and then developing the paper. Nothing new in that.

I want to start loading my tanks in there, rather than using a changing bag. I know I need to improve my door seals (any suggestions welcomed BTW). However once I think I'm OK, how can I check it? Being a 35mm, roll film user doesn't seem to lend itself to the coin test, and would the coin test be valid for film anyway? So how does one check to see if a darkroom is film safe?