> I also combed through the outputs to see what sorts of inputs were succeeding, what was failing, and observe how my program handled various edge cases. It was

> I also combed through the outputs to see what sorts of inputs were succeeding, what was failing, and observe how my program handled various edge cases. It was rejecting some inputs I thought should be valid, accepting some I thought should be invalid, and interpreting some in ways I hadn’t intended. So even after I fixed the crashing inputs, I still made tweaks to the parser to fix each of these troublesome inputs. I love just looking through the absurd stuff AFL comes up with, even if it's not causing a crash or incorrect behavior. Like this bit of art it caused my parser generator to produce: https://i.imgur.com/VoV7cU9.png https://i.imgur.com/VoV7cU9.png