Attempt to make the unit test more robust and clean up process management

resources.

Author: duaneg

Lib/test/test_concurrent_futures/executor.py

@@ -238,22 +238,23 @@ def test_shutdown_notifies_cancelled_futures(self):
         # gh-136655: ensure cancelled futures are notified
         count = self.worker_count * 2
         barrier = self.create_barrier(self.worker_count + 1)
-        fs = [self.executor.submit(blocking_raiser,
-                                   barrier if index < self.worker_count else None)
-              for index in range(count)]
-
-        self.executor.shutdown(wait=False, cancel_futures=True)
-        try:
-            barrier.wait()
-        except threading.BrokenBarrierError:
-            pass
-
-        for future in fs:
-            self.assertRaises(
-                (FalseyBoolException, futures.CancelledError, threading.BrokenBarrierError),
-                future.result)
-
-        self.assertIn('CANCELLED_AND_NOTIFIED', [f._state for f in fs])
+        with self.executor as exec:
+            fs = [exec.submit(blocking_raiser,
+                              barrier if index < self.worker_count else None)
+                  for index in range(count)]
+
+            exec.shutdown(wait=False, cancel_futures=True)
+            try:
+                barrier.wait()
+            except threading.BrokenBarrierError:
+                pass
+
+            for future in fs:
+                self.assertRaises(
+                    (FalseyBoolException, futures.CancelledError, threading.BrokenBarrierError),
+                    future.result)
+
+            self.assertIn('CANCELLED_AND_NOTIFIED', [f._state for f in fs])
 
 def blocking_raiser(barrier=None):
     if barrier is not None: