I'm interested to modify regrtest (test runner of the Python test suite) to use sys.unraisablehook(). It would be nice to add an option to display again *all* unraisable exceptions in the test summary, at the end.

I did a similar experimentation for any warnings, so my implementation was fragile because regrtest was hard to extend. That's why I introduced a new TestResult type: to be able to add more fields without breaking all the code. Prevously, a test result was a tuple which was manually unpacked. So adding a new field could break code which wasn't updated to handle new fields.