Winter is a great time to run germination tests. I like to do this for seeds with a short shelf life or that have been in my stash for so long, I don't remember when they were harvested.
Even if seeds have low germination (less than 50%) we can still plant them, just plant more of them to compensate.
Here is a quick
video on how I do my germination test
Pro tip: keep the seeds at the temperature they would grow normally. Tomatoes would like to be warm and dark - so maybe above the fridge.
Flax and peas like to grow in cooler conditions, so I keep them on the counter.