The "canary" is a common metaphor (for example in buffer overflow checks) for detecting mis-behaving operations by setting a flag before and verifying that it is still set after.
Is there a common term for the opposite, when the operation should kill the "canary"?
I actually don't like the canary term, because it causes silly conversations like "did you check the canary? Yeah, it's still alive" and you need the coal mine connotation to understand it. I prefer "buffer guard or guard pattern" so the inverse would be "goal pattern", because that is the data that should have been changed by your test.
Edit: of course, if you like the animal metaphor, you could use "fly" as in "did you manage to swat the fly?"
Maybe "sentinel"? Perhaps not quite so established for this particular case, but still often used for similar things.
How about a Rat? The voice would change from active to passive though. Instead of saying, Kill the Canary, we'd say the Rat is Dead. Cause its way cooler.
Also, the rat will be considered nonexistent until the operation misbehaves at which point we'd say, we have a rat.
"Canary" is an abbreviation of the term "canary in a coal mine". Canaries are more sensitive to poison gasses that humans, so a caged canary was used as a gauge of the presence of poison gas. The idea was that the canary would die from the poison gasses before humans even noticed them.
Find an opposite of that, if you can.
