bpo-30280: Cleanup threads in ayncio tests (#2501)

* bpo-30280: asyncio now cleans up threads

asyncio base TestCase now uses threading_setup() and
threading_cleanup() of test.support to cleanup threads.

* asyncio: Fix TestBaseSelectorEventLoop cleanup

bpo-30280: TestBaseSelectorEventLoop of
test.test_asyncio.test_selector_events now correctly closes the event
loop: cleanup its executor to not leak threads.

Don't override the close() method of the event loop, only override
the_close_self_pipe() method.

1 files changed, 3 insertions, 5 deletions

diff --git a/Lib/test/test_asyncio/test_selector_events.py b/Lib/test/test_asyncio/test_selector_events.py
index 6bf7862..c50b3e4 100644
--- a/Lib/test/test_asyncio/test_selector_events.py
+++ b/Lib/test/test_asyncio/test_selector_events.py
@@ -24,16 +24,14 @@ MOCK_ANY = mock.ANY
 
 class TestBaseSelectorEventLoop(BaseSelectorEventLoop):
 
-    def close(self):
-        # Don't call the close() method of the parent class, because the
-        # selector is mocked
-        self._closed = True
-
     def _make_self_pipe(self):
         self._ssock = mock.Mock()
         self._csock = mock.Mock()
         self._internal_fds += 1
 
+    def _close_self_pipe(self):
+        pass
+
 
 def list_to_buffer(l=()):
     return bytearray().join(l)