We were testing the arguments that were being passed to qemu when a disk
was being served by nbdkit, but the arguments used to start nbdkit
itself were not testable. This adds a test to ensure that we're invoking
nbdkit correctly for various disk source definitions.
Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>