Fix logic for Notifier.listeners_for

Add tests for proper logic around notifier

tests/test_notifier.py

@@ -8,7 +8,7 @@ class _Listener(object):
         self.was_notified = False
 
     def notify(self, error_code, *args, **kwargs):
-        assert self.error_code == error_code
+        assert error_code.startswith(self.error_code)
         self.was_notified = True
 
 
@@ -18,14 +18,18 @@ class TestNotifier(object):
         self.notifier = notifier.Notifier()
         self.listener_map = {}
 
-        for i in range(10):
-            for j in range(30):
-                error_code = 'E{0}{1:02d}'.format(i, j)
-                listener = _Listener(error_code)
-                self.listener_map[error_code] = listener
-                self.notifier.register_listener(error_code, listener)
+        def add_listener(error_code):
+            listener = _Listener(error_code)
+            self.listener_map[error_code] = listener
+            self.notifier.register_listener(error_code, listener)
 
-    def test_notify_a_single_error_code(self):
+        for i in range(10):
+            add_listener('E{0}'.format(i))
+            for j in range(30):
+                add_listener('E{0}{1:02d}'.format(i, j))
+
+    def test_notify(self):
         """Show that we notify a specific error code."""
         self.notifier.notify('E111', 'extra', 'args')
         assert self.listener_map['E111'].was_notified is True
+        assert self.listener_map['E1'].was_notified is True