A battery can have 12v and almost no cranking amps, if im not mistaken.
I'm sure it's not recommended my most people here, but I do it all this all the time (after I've rotated the engine by hand to make sure it's not froze up.)
Turn the key on. Take a pair of jumper cables and attach the one end of one cable to the positive on the battery. Then just touch the other end of that same cable to starter, where the red wire connects. That will tell you if your battery has no cranking amp. And if it does, then it'll tell you if you starter is good.