What kink of tool can test a fuel injector on the engine?

I've heard the term "noid light"
I this available to be purchased someplace.
I imagine that it works to see that power get to the injector and it pulses.
Can anyone enlighten me on this?
thx

Go to an auto supply house and see if they offer this tool . If not , perhaps they can order it for you .

I thought so,there must be a good source for that,I mean I'm looking the same thing.

I think it is their on ebay . I was surfing about it a week or two back !
Or try the auto store !