For the most part, aluminum roofs hold out water very well. Standing seams or through holes and where the aluminum attaches to the wall are likely to leak if not sealed correctly.
A pressurized leak test (I've found) is the best way to find any leaks. Even a pinhole will turn up with the test.
FWIW, I have an aluminum roof and even after applying a lot of sealant to likely areas, I had a couple of pinhole leaks. The pressure test turned up those spots and I decided to use Eternabond tape to those areas. I test yearly for leaks and my aluminum roof has remained leak free.