I'm not sure if that's an article failure (that I didn't want to read a whole ton of text and C code details), or a success (as it got me interested in the topic). I guess both?
Also, do test case reducers work on integers or other numbers? What about reducing some other complexity? Is this for developing unit tests or just debugging?
Imagine being handed a sheet of 10 equations and being told "1 of these equations is wrong." Now imagine that someone came in and erased 8 of the correct equations - they just saved you a bunch of time.
Similarly, narrowing test cases to the smallest case that reproduces a particular behaviour so you're only actually testing a very targeted thing will make the test suite faster and also make it easier to fix tests which break because they exercise a very narrow path.
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaẞ
Boy I sure do wonder what character could possibly be causing issues there. whereas without shrinking it might instead spit out something like
ЁЂЃЄЅІЇЈЉЊЋЌЍЎЏАБВГДẞЕЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯабвгдежзийклмноп
Which makes finding the offending character a lot harder.
It's answered pretty early on:
>> Test-case reducers try to reduce the length of an input
If that still doesn't answer the question, try this extension:
>> Test-case reducers try to reduce the length of an [error causing or interesting] input
There's no C in there? It seems to be Python and shell scripts.