[Findit] Extract failed output nodes from stdio log of compile step.

appengine/findit/waterfall/test/failure_signal_test.py

 # Copyright 2014 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 unittest
 
 from waterfall.failure_signal import FailureSignal
 
 
 class FailureSignalTest(unittest.TestCase):
@@ skipping 29 matching lines @@
         signal.failed_targets)
 
   def testToFromDict(self):
     data = {
         'files': {
             'a.cc': [2],
             'd.cc': []
         },
         'keywords': {
             'k1': 3
-        }
+        },
+        'failed_output_nodes': [
+            'obj/path/to/file.o',
+        ],
     }
     signal = FailureSignal.FromDict(data)
     self.assertEqual(data, signal.ToDict())
 
   def testToFromDictWithFailedTargets(self):
     data = {
         'files': {
             'a.cc': [2],
             'd.cc': []
         },
@@ skipping 66 matching lines @@
             'target': 'b.o',
             'source': 'b.cc'
         },
         {
             'target': 'c.exe'
         }
     ]
 
     self.assertEqual(expected_step_signal_files, step_signal.files)
     self.assertEqual(expected_step_failed_targets, step_signal.failed_targets)