Summary:
The usage of libinput is completely mocked. The test covers all the
constant properties read by Device.
There are some features which are not yet tested:
* alphaNumericKeyboard
* supportedButtons
* enabled
The setters for leftHanded and pointerAcceleration are also covered
including the variants where it can fail.
Reviewers: #plasma
Subscribers: plasma-devel
Tags: #plasma
Differential Revision: https://phabricator.kde.org/D1648
