test: remove unnecessary engine instance

tests/test_channels.py

@@ -30,7 +30,7 @@ from aura_engine.core.channels import (
     StreamChannel,
 )
 from aura_engine.core.mixer import Mixer
-from aura_engine.engine import Engine, EngineEventDispatcher
+from aura_engine.engine import EngineEventDispatcher
 
 from .mock import PlayoutClientMock
 
@@ -48,8 +48,7 @@ class TestChannelFactory(unittest.TestCase):
         AuraLogger(config)
         self.logger = logging.getLogger("engine-tests")
 
-        engine = Engine()
-        dispatcher = EngineEventDispatcher(engine=engine)
+        dispatcher = EngineEventDispatcher(engine=None)
         client = PlayoutClientMock(event_dispatcher=dispatcher)
         self.mixer = client.mixer
         self.factory = ChannelFactory(self.mixer)