Using the branch here, running the .solo() test times out during cleanup:
https://github.com/Dart-Code/Dart-Code/tree/bug-repro
5099a4d
It seems that the initial terminateRequest never completes, with just "Waiting for current test to finish".
We're supposed to unpause when we try to shutdown, so the tests should complete quite quickly, and then termination should complete normally. That doesn't seem to be happening though.