Ouch, I can't use srfi-64 test-group inside asyncronous code, because it uses dynamic-wind and re-entering fiber's continuation messes up test-runner output:
https://git.savannah.gnu.org/cgit/guile.git/tree/module/srfi/srfi-64/testing.scm?h=0e9ccaf47#n443
@abcdw How about guile-tap instead?