add support.set_event_loop_policy for setting the event loop policy in tests

Author: graingert

Lib/test/libregrtest/save_env.py

@@ -97,7 +97,7 @@ def get_asyncio_events__event_loop_policy(self):
         return support.maybe_get_event_loop_policy()
     def restore_asyncio_events__event_loop_policy(self, policy):
         asyncio = self.get_module('asyncio')
-        asyncio.set_event_loop_policy(policy)
+        support.set_event_loop_policy(policy)
 
     def get_sys_argv(self):
         return id(sys.argv), sys.argv, sys.argv[:]

Lib/test/support/__init__.py

@@ -2089,6 +2089,13 @@ def maybe_get_event_loop_policy():
     import asyncio.events
     return asyncio.events._event_loop_policy
 
+def set_event_loop_policy(policy):
+    """Set the global event loop policy ignoring deprecation warnings"""
+    import asyncio
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", DeprecationWarning)
+        asyncio.set_event_loop_policy(policy)
+
 # Helpers for testing hashing.
 NHASHBITS = sys.hash_info.width # number of bits in hash() result
 assert NHASHBITS in (32, 64)