Testing coils

Hey i am new to working on small motors...i spent years working as a heavy duty mechanic...so now in my spare time i started tinkering on small motors..i work on all types...and will have tons of questions as they come up..one of the first ones i have is how to check a coil on a merc outboard,one of the 2 has cracks all over it, i have tried looking it up and it just gives generalizations..would anybody be able to point me in the right direction😁thanks in advance