DumpDir prints the contents of the directory to the testing logger.

DumpDirOnFailure prints the contents of the directory to the testing logger if the test has failed.

NewLoopback creates a loopback device, and returns its device name (/dev/loopX), and its clean-up function.

RequiresRoot skips tests that require root, unless the test.root flag has been set.

RequiresRootM is similar to RequiresRoot but intended to be called from *testing.M.

Unmount unmounts a given mountPoint and sets t.Error if it fails.