Proper way to recover 18650 cells from laptop batteries
This is more, or less a good approach. If you know what the cells are, then you can compare the capacity it is showing with what it was showing when it was new. The other thing you could do would be to test them under a load closer to their rated load and see how they perform; do they sag badly, do the get very hot? 

Lastly, be careful, you could get some fire out of them.