gh-127949: fix resource warnings in test_tasks.py (GH-128172)

(cherry picked from commit b66a4ad)

Co-authored-by: Thomas Grainger <[email protected]>

Author: graingert

Lib/test/test_asyncio/test_tasks.py

@@ -2499,17 +2499,17 @@ def __str__(self):
         initial_refcount = sys.getrefcount(obj)
 
         coro = coroutine_function()
-        loop = asyncio.new_event_loop()
-        task = asyncio.Task.__new__(asyncio.Task)
+        with contextlib.closing(asyncio.EventLoop()) as loop:
+            task = asyncio.Task.__new__(asyncio.Task)
 
-        for _ in range(5):
-            with self.assertRaisesRegex(RuntimeError, 'break'):
-                task.__init__(coro, loop=loop, context=obj, name=Break())
+            for _ in range(5):
+                with self.assertRaisesRegex(RuntimeError, 'break'):
+                    task.__init__(coro, loop=loop, context=obj, name=Break())
 
-        coro.close()
-        del task
+            coro.close()
+            del task
 
-        self.assertEqual(sys.getrefcount(obj), initial_refcount)
+            self.assertEqual(sys.getrefcount(obj), initial_refcount)
 
 
 def add_subclass_tests(cls):