[Findit] Implementing swarming task error detection

appengine/findit/waterfall/test/trigger_flake_swarming_task_pipeline_test.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import time
 
 from model import analysis_status
 from model.flake.flake_swarming_task import FlakeSwarmingTask
 from waterfall import swarming_util
 from waterfall.swarming_task_request import SwarmingTaskRequest
@@ skipping 78 matching lines @@
           },
           'tags': ['master:a', 'buildername:b', 'name:a_tests'],
           'user': 'user',
       })
     self.mock(swarming_util, 'GetSwarmingTaskRequest',
               MockedGetSwarmingTaskRequest)
 
     new_request_json = {}
     def MockedTriggerSwarmingTask(new_request, *_):
       new_request_json.update(new_request.Serialize())
-      return 'new_task_id'
+      return 'new_task_id', None
     self.mock(swarming_util, 'TriggerSwarmingTask', MockedTriggerSwarmingTask)
 
     def MockedGetSwarmingTaskName(*_):
       return 'new_task_name'
     self.mock(TriggerFlakeSwarmingTaskPipeline, '_GetSwarmingTaskName',
               MockedGetSwarmingTaskName)
 
     master_name = 'm'
     builder_name = 'b'
     build_number = 234
@@ skipping 37 matching lines @@
     self.assertEqual(expected_new_request_json, new_request_json)
 
     swarming_task = FlakeSwarmingTask.Get(
         master_name, builder_name, build_number, step_name, tests[0])
     self.assertIsNotNone(swarming_task)
     self.assertEqual('new_task_id', swarming_task.task_id)
     self.assertEqual(tests, swarming_task.parameters['tests'])
     self.assertEqual(
         pipeline._GetIterationsToRerun(),
         swarming_task.parameters['iterations_to_rerun'])