This is not a new a testing method, I have a Dilog Beha LT277 discharge lamp tester that works in a similar way and that was purchased over 20 years ago. It's not as neat and compact as the modern offerings from TIS, Martindale, Milwaukee and others, but it does job very efficiently. It has one distinct advantage over it's modern counterparts, namely, it provides a standard "radio" telescopic aerial in the kit which saves getting out the steps when testing most ceiling mounted lamps in circuit.