test: add delay to simulate loading time

tests/test_engine_scheduler.py

@@ -119,6 +119,7 @@ class CoreClientMock(CoreClient):
                 return "volume=100% remaining=1 selected=1"
         elif namespace in ChannelName._value2member_map_.values():
             if action == "push":
+                sleep(5)  # simulate some loading time
                 return 1  # res id
 
 
@@ -184,7 +185,7 @@ class TestPlayCommand(unittest.TestCase):
         entry.entry_start = datetime.now()
         entry.duration = 60.0
         entry.volume = 100
-        entry.source = "file:///file.aif"
+        entry.source = "file:///fake.wav"
         entry.playlist = playlist
 
         entries = [entry]