refactor: Replaced tests asserting that the event loop is properly cl…

…osed.

Under Python 3.10, the tests raise:
"DeprecationWarning: There is no current event loop"
This means that the asyncio.get_event_loop does not return any existing loop. It creates a new loop as a side effect instead. Therefore, test_1 and test_3 will always be successful.

However, it would be wrong to simply delete the tests without a replacement. Although, we cannot retrieve the default loop with get_event_loop, we can still retrieve it from the event loop policy. The new tests do exactly that and assert that the loop is a different object than in the tests before.

Signed-off-by: Michael Seifert <m.seifert@digitalernachschub.de>

tests/test_event_loop_scope.py

@@ -1,22 +1,31 @@
-"""Test the event loop fixture is properly disposed of.
+"""Test the event loop fixture provides a separate loop for each test.
 
 These tests need to be run together.
 """
 import asyncio
 
 import pytest
 
+loop: asyncio.AbstractEventLoop
+
 
 def test_1():
-    loop = asyncio.get_event_loop()
-    assert not loop.is_closed()
+    global loop
+    # The main thread should have a default event loop.
+    loop = asyncio.get_event_loop_policy().get_event_loop()
 
 
 @pytest.mark.asyncio
 async def test_2():
-    pass
+    global loop
+    running_loop = asyncio.get_event_loop_policy().get_event_loop()
+    # Make sure this test case received a different loop
+    assert running_loop is not loop
+    loop = running_loop  # Store the loop reference for later
 
 
 def test_3():
-    loop = asyncio.get_event_loop()
-    assert not loop.is_closed()
+    global loop
+    current_loop = asyncio.get_event_loop_policy().get_event_loop()
+    # Now the event loop from test_2 should have been cleaned up
+    assert loop is not current_loop