/usr/lib/x86_64-linux-gnu/libQt5QuickTest.so is in qtdeclarative5-dev 5.7.1-2+b2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libQt5QuickTest.so.5.7.1
/usr/lib/x86_64-linux-gnu/libQt5QuickTest.so.5.7.1