I may be misunderstanding some concepts here, but as far as I know, each disk has a partition table and actual partitions.
I'm looking to test a hard drive for bad sectors and errors, but the tools I found to do this are meant for partitions -- not disks. badblocks takes a partition /dev/sda1 not /dev/sda. Same story with e2fsck.
As far as I understand, those tools only test space assigned to partitions, not a whole disk. Is there any way to test an entire disk?