Fix CI issues related to asyncio (#5782)

scrapy/utils/defer.py

@@ -26,7 +26,7 @@ from twisted.python import failure
 from twisted.python.failure import Failure
 
 from scrapy.exceptions import IgnoreRequest
-from scrapy.utils.reactor import is_asyncio_reactor_installed, get_asyncio_event_loop_policy
+from scrapy.utils.reactor import is_asyncio_reactor_installed, _get_asyncio_event_loop
 
 
 def defer_fail(_failure: Failure) -> Deferred:
@@ -267,7 +267,7 @@ def deferred_from_coro(o) -> Any:
             # that use asyncio, e.g. "await asyncio.sleep(1)"
             return ensureDeferred(o)
         # wrapping the coroutine into a Future and then into a Deferred, this requires AsyncioSelectorReactor
-        event_loop = get_asyncio_event_loop_policy().get_event_loop()
+        event_loop = _get_asyncio_event_loop()
         return Deferred.fromFuture(asyncio.ensure_future(o, loop=event_loop))
     return o
 
@@ -318,8 +318,7 @@ def deferred_to_future(d: Deferred) -> Future:
                 d = treq.get('https://example.com/additional')
                 additional_response = await deferred_to_future(d)
     """
-    policy = get_asyncio_event_loop_policy()
-    return d.asFuture(policy.get_event_loop())
+    return d.asFuture(_get_asyncio_event_loop())
 
 
 def maybe_deferred_to_future(d: Deferred) -> Union[Deferred, Future]:

scrapy/utils/reactor.py

@@ -1,6 +1,7 @@
 import asyncio
 import sys
 from contextlib import suppress
+from warnings import catch_warnings, filterwarnings
 
 from twisted.internet import asyncioreactor, error
 
@@ -81,6 +82,10 @@ def install_reactor(reactor_path, event_loop_path=None):
             installer()
 
 
+def _get_asyncio_event_loop():
+    return set_asyncio_event_loop(None)
+
+
 def set_asyncio_event_loop(event_loop_path):
     """Sets and returns the event loop with specified import path."""
     policy = get_asyncio_event_loop_policy()
@@ -90,11 +95,26 @@ def set_asyncio_event_loop(event_loop_path):
         asyncio.set_event_loop(event_loop)
     else:
         try:
-            event_loop = policy.get_event_loop()
+            with catch_warnings():
+                # In Python 3.10.9, 3.11.1, 3.12 and 3.13, a DeprecationWarning
+                # is emitted about the lack of a current event loop, because in
+                # Python 3.14 and later `get_event_loop` will raise a
+                # RuntimeError in that event. Because our code is already
+                # prepared for that future behavior, we ignore the deprecation
+                # warning.
+                filterwarnings(
+                    "ignore",
+                    message="There is no current event loop",
+                    category=DeprecationWarning,
+                )
+                event_loop = policy.get_event_loop()
         except RuntimeError:
-            # `get_event_loop` is expected to fail when called from a new thread
-            # with no asyncio event loop yet installed. Such is the case when
-            # called from `scrapy shell`
+            # `get_event_loop` raises RuntimeError when called with no asyncio
+            # event loop yet installed in the following scenarios:
+            # - From a thread other than the main thread. For example, when
+            #   using ``scrapy shell``.
+            # - Previsibly on Python 3.14 and later.
+            #   https://github.com/python/cpython/issues/100160#issuecomment-1345581902
             event_loop = policy.new_event_loop()
             asyncio.set_event_loop(event_loop)
     return event_loop

tests/test_utils_asyncio.py

@@ -14,6 +14,9 @@ class AsyncioTest(TestCase):
         self.assertEqual(is_asyncio_reactor_installed(), self.reactor_pytest == 'asyncio')
 
     def test_install_asyncio_reactor(self):
+        from twisted.internet import reactor as original_reactor
         with warnings.catch_warnings(record=True) as w:
             install_reactor("twisted.internet.asyncioreactor.AsyncioSelectorReactor")
             self.assertEqual(len(w), 0)
+        from twisted.internet import reactor
+        assert original_reactor == reactor