test: add 'event_loop' fixture

Default event loop is being closed after running
`async` tests from test_pubsub.py. This fails
subscribe and unsubscribe handler tests.
Need to create an instance for default event
loop for all the async tests.

Signed-off-by: Jeny Sadadia <jeny.sadadia@collabora.com>

test/conftest.py

@@ -11,6 +11,7 @@
 """pytest fixtures for KernelCI API"""
 
 from unittest.mock import AsyncMock
+import asyncio
 import fakeredis.aioredis
 from fastapi.testclient import TestClient
 import pytest
@@ -35,6 +36,15 @@ def client():
     return TestClient(app)
 
 
+@pytest.fixture
+def event_loop():
+    """Create an instance of the default event loop for each test case"""
+    loop = asyncio.new_event_loop()
+    asyncio.set_event_loop(loop)
+    yield loop
+    loop.close()
+
+
 @pytest.fixture
 def mock_db_create(mocker):
     """Mocks async call to Database class method used to create object"""