This is such a great idea! I've really struggled with how to test real-time audio code in the live looper I've been working on [0]. Most of my tests use either very small, hand-constructed arrays, or arrays generated by some function.
This is both tedious and makes it very hard to debug test failures (especially with cases like crossfades, pan laws, and looping). I love the idea of having a visual representation that lets me see what's going wrong in the test output, and I'm definitely going to try to implement some similar tests.
I'm also curious what the state-of-the-art is for these sorts of tests. Does anyone have insight into what e.g., ableton's test suite looks like?