test_hub_join_timeout.py: add testcase for passing Event()

greentest/test_hub_join_timeout.py

 from __future__ import with_statement
 from contextlib import contextmanager
 import gevent
+from gevent.event import Event
 from time import time
 
 
@@ -56,6 +57,22 @@ for _a in xrange(2):
             result = gevent.get_hub().join()
         assert result is True
 
+    # exiting because of event (the spawned greenlet still runs)
+    for _ in xrange(2):
+        x = gevent.spawn_later(10, lambda: 5)
+        event = Event()
+        event_set = gevent.spawn_later(SMALL, event.set)
+        with expected_time(SMALL):
+            result = gevent.get_hub().join(event=event)
+        assert result is None, repr(result)
+        assert not x.dead, x
+        assert event_set.dead
+        assert event.is_set()
+        x.kill()
+        with no_time():
+            result = gevent.get_hub().join()
+        assert result is True
+
     # checking "ref=False" argument
     for _ in xrange(2):
         gevent.get_hub().loop.timer(10, ref=False).start(lambda : None)