When boiled, instant water test. Other types, when I’m not particularly confident, I just crack open to a bowl.

I’m used to this because I grew up with eggs from hens of friends and family so we never knew when they were laid or how long they were in the hen house… Anyway, with store bought eggs, never had a problem, even after months (only 1 bad batch that came from the supermarket).

If you refrigerate unwashed European eggs, they will last multiple months (I have kept eggs for more then 2 months), way past the expiration date on the packaging (I know because I do it constantly).