Starting

What is it doing? Cranking over and will not start or just won't crank at all/nothing when you turn key to cranking position?

A battery drain with everything turned off? As far as testing the alternator and battery, the testing needs to be done with everything hooked up on the vehicle. Testing the alternator off the vehicle, a problem with alternator or battery wiring, that won't show-up.

If you have a drain, check for any lites left on, interior--under the hood, in the trunk. Best time to check is in the dark. An older way to check for drain, is to take battery cable loose, use testlite between cable and battery post, everything turned off, if lite come on, you have a drain. If the problem is on a fused circuit, you pull/replace fuses one at a time. When you pull the fuse on a faulty circuit, the lite goes out.

If you pull every fuses and the test lite still On disconnect the alternator and see what happens