By separating them from unrelated code, their dependents
can use them without depending on unrelated code, which
in turn helps to reduce cyclic dependencies.
QSysInfo::machineUniqueId() was added in Qt 5.11 and is using DBus independent unique machine ids everywhere except on Linux. This prevents running into an assert in case DBus is not properly installed at a very early stage of the application without any chance to give the user a warning and handle it gracefully.
This is an intermediate step to have smaller unit tests. It is a trade off
between having many many test executables compared to a few bigger ones. But
this comes a lot closer to what QtTest is meant to be used.
