https://www.kickstarter.com/projects/955316598/simple-led-tester-every-lab-should-have-one?ref=discovery
I saw this on a developers website and thought it was a good idea
I know I’ve killed a good number of LEDs just by testing them
It might be good for 5mm LEDs but nobody uses those in lights anymore.
I don’t think I’ve ever killed an LED by testing it… are you hooking up a car battery to them or something?
Why, is that not a good idea?
(^^^Toyota trunk light conversion)
I just use the diode test on my multimeter.
When I reflow my emitters onto copper stars, I take a small single cell Li Ion and bump the connections on the star with the leads from the holder…usually glare blind myself in the process 
+1
I have this one, which is more versatile than the one from the OP:
The 9V block lasts forever, it has different currents, and with the little clamps I can test any led, even series of 3+ leds light up.
But I am kind of charmed by the idea of a simple board tester, but I would want pads for the various sizes of leds on the market, so 5mm through-hole, standard 3535 footprint, xml, mtg, luxeon Z, luxeon T, Oslon, sst90 etc. Oh, and a clicky switch instead of the momentary one, so to test you can just push the leds (with a forceps) on the corresponding pads (thickened with a solder blob) on the board.
Likewise
I use a Fluke 289 to test diodes;
and can measure the minimum VF which starts to conduct the LED
(I think about 10mA);)
Very useful if you should use the LEDs in parallel.
some LED is claimed to have a life span of 100000 hours,anyone test it?How do they test it? 
This is usual tested with accelerated tests. This is based on knowledge about how lifetime is reduced at high temperatures.
I.e. a test at 100C may show 10000 hours lifetime and by knowing how the temperature affect lifetime it is possible to say 100000 hours at 40C.
Yes,100000 hours can not be tested,it is really a long time.
I was planning on ordering a few of the 7135 test board that could be used this way. If you’re interested I can increase my order and send you a few.