Extracting Ns._create_ro_task() and creating unit test

Extracted the _create_ro_task() to ease the testability of that code.
Introduced a unit test to cover that function.

Change-Id: I684ba7fc63e1d77545c84517024f541a9e630573
Signed-off-by: sousaedu <eduardo.sousa@canonical.com>
3 files changed