I'd like to know whether there is somewhere I can add unit tests for this (not sure if playback things can be unit-tested?). Please advise and I will add them. Thanks!

Hi @totalgee
Here's an example of unit test that "plays" sound and checks for its correctness: https://github.com/supercollider/supercollider/blob/develop/testsuite/classlibrary/TestCoreUGens.sc
Please note that these particular tests are a bit abstracted to facilitate running multiple tests with a similar structure, but the main takeaway is that you need to set up a dedicated server, .bootSync it, then run <function>.loadToFloatArray and finally quit the server.
Any tests you add to the classlibrary directory will be run in the CI
Does that answer your question?

(PS I don't know what the macOS arm64 failure is about, it's not related to your PR, I'll look into it) EDIT: it worked on the second attempt

Thanks @dyfer, I'll add a few unit tests and push those when I can. I don't need the server/audio, just need to play some Pdefs on a TempoClock. I'll try it my way, then someone can correct me if they don't like it, or there's a simpler approach. (-;

There are definitely examples of Pattern tests in our UnitTests, feel free to take a look at them.

I just finished adding some unit tests that cover the time-related problems this fixes. I capture values out of playing Patterns (Pdefs) and compare them with what is expected.

Thanks!