Fixes and added tests for the security notification worker

Fixes #1301

- Ensures that the worker uses pagination properly
- Ensures that the worker handles failure as expected
- Moves marking the notification as read to after the worker processes it
- Increases the number of layers requested to 100

util/secscan/api.py

@@ -160,7 +160,7 @@ class SecurityScannerAPI(object):
     return False
 
 
-  def get_notification(self, notification_name, layer_limit=10, page=None):
+  def get_notification(self, notification_name, layer_limit=100, page=None):
     """ Gets the data for a specific notification, with optional page token.
         Returns a tuple of the data (None on failure) and whether to retry.
     """
@@ -194,7 +194,7 @@ class SecurityScannerAPI(object):
     """ Marks a security scanner notification as read. """
     try:
       response = self._call('DELETE', _API_METHOD_MARK_NOTIFICATION_READ % notification_name)
-      return response.status_code == 200
+      return response.status_code / 100 == 2
     except requests.exceptions.RequestException:
       logger.exception('Failed to mark notification as read: %s', notification_name)
       return False