Fix test_alertmanager

tests/test_alertmanager.py

@@ -4,14 +4,23 @@ import common
 
 from deluge.core.alertmanager import AlertManager
 from deluge.core.core import Core
+import deluge.component as component
 
 class AlertManagerTestCase(unittest.TestCase):
     def setUp(self):
         self.core = Core()
 
-        self.am = AlertManager()
-        self.am.start()
+        self.am = component.get("AlertManager")
+        component.start(["AlertManager"])
 
+    def tearDown(self):
+        def on_shutdown(result):
+            component._ComponentRegistry.components = {}
+            del self.am
+            del self.core
+
+        return component.shutdown().addCallback(on_shutdown)
+        
     def test_register_handler(self):
         def handler(alert):
             return