There’s nothing wrong with the 12.79 volts except for one thing. That does not tell you what the voltage is when a heavy load is applied; such as a starter motor.
The only way to determine this is by load testing the battery and applying a load equal to 3 X the starter current draw. After 15 seconds it should be a minimum of 10.2 volts.
This also means the battery should be on a charger for at least .5 an hour before a test and preferably an hour.
I’ve seen Wal Mart test batteries with no consideration given as to whether they’re testing a battery that has been run down by cranking or one that is weak due to someone leaving the lights on. Bad way of doing it in my opinion.
A few years ago I went into WM to buy a battery for a project car of mine and took along a 6 month old WM battery that I knew for a fact was good but was simply run down. I did this just for a hoot and sure enough, they tested it and proclaimed it DOA.
They then offered to exchange it since it was still covered under a non-prorated warranty. I refused the offer and the battery is still chugging along fine at 3 years of age.