Fix warnings and resource usage problems in asyncio unittests (#2258)

* Use pytest-asyncio in auto mode
Remove overly genereric `pytestmark=pytest.mark.asyncio` causing lots of warning noise

* Use "Factories as Fixtures" test pattern for the `create_redis` fixture
this fixture is now async, avoiding teardown problems with missing event loops.

* Fix sporadic error on fast event loops, such as `--uvloop`

* Close connection, even if "username" was in kwargs
This fixes a resource usage warning in the async unittests.

* Do async cleanup of acl passwords via a fixture

* Remove unused import, fix whitespace

* Fix test with missing "await"

* Close pubsub objects after use in unittest
Use a simple fixture where possible, otherwise manually call pubsub.close()

* re-introduce `pytestmark=pytest.mark.asyncio` for python 3.6

* Use context manager to clean up connections in connection pool for unit tests

* Provide asynccontextmanager for python 3.6

* make `test_late_subscribe()` more robuste

* Catch a couple of additional leaked resources

1 files changed, 3 insertions, 1 deletions

diff --git a/tests/test_asyncio/test_connection.py b/tests/test_asyncio/test_connection.py
index 78a3efd..8030f7e 100644
--- a/tests/test_asyncio/test_connection.py
+++ b/tests/test_asyncio/test_connection.py
@@ -1,5 +1,6 @@
 import asyncio
 import socket
+import sys
 import types
 from unittest.mock import patch
 
@@ -18,7 +19,8 @@ from tests.conftest import skip_if_server_version_lt
 
 from .compat import mock
 
-pytestmark = pytest.mark.asyncio
+if sys.version_info[0:2] == (3, 6):
+    pytestmark = pytest.mark.asyncio
 
 
 @pytest.mark.onlynoncluster