Currently, test_eintr is complelty skipped on Windows. time.sleep() was also patched on Windows to retry when interrupted by a signal (issue #23646) and I was able to see a different when testing manually.

test_eintr is currently implemented with signal.setitimer() and os.fork(). Windows doesn't have signal.setitimer(), signal.alarm(), nor os.fork(), but it's possible to send a signal to another process using os.kill() (by the way, see the issue #14484 "missing return in win32_kill?").

At least, time.sleep() should be tested on Windows.