test: move wait_for_first_completed to pylib/util.py

This function is needed in a new test added in the next commit and this
refactoring avoids code duplication.

test/pylib/util.py

@@ -3,6 +3,7 @@
 #
 # SPDX-License-Identifier: AGPL-3.0-or-later
 #
+from collections.abc import Coroutine
 import threading
 import time
 import asyncio
@@ -246,3 +247,11 @@ async def wait_for_view(cql: Session, name: str, node_count: int, timeout: int =
         return done[0][0] == node_count or None
     deadline = time.time() + timeout
     await wait_for(view_is_built, deadline)
+
+
+async def wait_for_first_completed(coros: list[Coroutine]):
+    done, pending = await asyncio.wait([asyncio.create_task(c) for c in coros], return_when=asyncio.FIRST_COMPLETED)
+    for t in pending:
+        t.cancel()
+    for t in done:
+        await t

test/topology/test_coordinator_queue_management.py

@@ -4,6 +4,7 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 #
 from test.pylib.manager_client import ManagerClient
+from test.pylib.util import wait_for_first_completed
 from test.topology.conftest import skip_mode
 from collections.abc import Coroutine
 import pytest
@@ -12,13 +13,6 @@ import asyncio
 
 logger = logging.getLogger(__name__)
 
-async def wait_for_first_completed(coros: list[Coroutine]):
-    done, pending = await asyncio.wait([asyncio.create_task(c) for c in coros], return_when = asyncio.FIRST_COMPLETED)
-    for t in pending:
-        t.cancel()
-    for t in done:
-        await t
-
 @pytest.mark.asyncio
 @skip_mode('release', 'error injections are not supported in release mode')
 async def test_coordinator_queue_management(manager: ManagerClient):