Test::Tiny and/or TAP::Tiny?
Perl test output (the so-called "Test Anything Protocol" or "TAP") is simple: "1..N" declaring that N tests are planned, then either comments starting with "#", or lines starting with "ok X" or "not ok X" saying whether or not test number X succeeded. Generating it should be simple. Parsing it should be almost as simple.
However, the code to generate and parse test output is a byzantine nightmare: Test::Simple and its dependencies are at least 1345 SLOC, and the various TAP-parsing modules are at least 3918 SLOC (including an IteratorFactory!).
Both generating and parsing the subset of "TAP" used by most programs can take around 50 SLOC. This seems like a perfect opportunity for a ::Tiny module.