If the Q_VERIFY(current >= previousValue) fails, the output was
not verbose enough. The additional outputs will tell us more about
what caused the test to fail.

Task-number: QTBUG-57839
Change-Id: Ieeefe68ede111be7dba5eda9f2a770e975efc0ee
Reviewed-by: Kai Koehne <kai.koehne@qt.io>