Klicks in, r1 r2 test to furthest fitting, L and N joined toogether at DB and IR test to earth (Line1 and Line 2 if emgy. fittings.
Earth loop test at furthest fitting and polarity test at all others.
Light fittings might be connected by flex but they are still a permanent fixture and as such should be included in testing. This will also show up faulty fittings, ballasts leaking to earth, incorrect (usually all white single) wiring etc.
Testing only to the klick box is doing half a job.
Boydy