This allows ostree-prepare-root outside of the initramfs context where the
real rootfs is already mounted at /. We can't use `mount --move` in this
case because we would be trying to move / into a subdirectory of itself.
Closes: #403
Approved by: cgwalters
These tests use unshare and mount to prepare a fake initrd/early boot
directory structure so we can then test ostree-prepare-root.
Things that are tested:
* Running in an initrd environment
* Running without initrd
* /var and /sysroot being mounted correctly
* /usr being mounted read-only
Things not tested (yet):
* Running as init - this could be accomplished by unsharing the pid
namespace too.
* mounting/unmounting `/proc` if `/proc/cmdline` isn't available
* Persistent overlayfs for `/usr`
* Probably other things
The tests are basic but can be extended in the future as we do more work
on `ostree-prepare-root`.
These tests must be run as root as they require the ability to `mount`
and to `unshare` the mount namespace. Perhaps in the future we can use
user namespaces for this test once they are more widely available.
Closes: #403
Approved by: cgwalters
William Manley