Detonator tester, done that with a tester, sweat or what...
It happened when the electric dets failed to go off in a tunnel round I was drilling and blasting down a tin mine with the boss man, there was always two of us drilling using two machines side by side, a young early twenty something me as a relative newbie, and the boss man aka "the machine man" but only one of us was allowed to go in to test for a misfire...I was given the short straw! It was sweaty enough as it was, 2,000 ft down then a good quarter of a mile into tombstone granite via a pokey tunnel barely 6Ft high in places, temp. at the face somewhere around 80 F on a good day.
A typical tin mine tunnel blasting round where I worked back then would be about 33 holes so 32 dets for a five hole burn cut, used dets with different delays to get the correct breakout sequence from the reamer hole otherwise impressive bangs but everything hangs up so no pay dirt, usual fault finding procedure to find the offending culprit, this way that way, this way that way until it's found, only problem was sticking a new det into the charge, can only be done from the face end of the charged hole and not the back end when you are on contract and got a two man night shift mucking crew to support, that means the primer is no longer at the back of the hole
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Having said that it's not as scary as going to attend a misfire due to a safety fuse not going off, now that's really brow dripping stuff....
Lawrence.