[Findit] Check for availability of try-job result.

appengine/findit/findit_api.py

 # Copyright 2015 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.
 
 """This module is to provide Findit service APIs through Cloud Endpoints:
 
 Current APIs include:
 1. Analysis of compile/test failures in Chromium waterfalls.
    Analyzes failures and detects suspected CLs.
 """
@@ skipping 118 matching lines @@
       try_job_key = try_job_map.get(step_name, {}).get(test_name)
 
     if not try_job_key:
       return None
 
     try_job = WfTryJob.Get(*try_job_key.split('/'))
     if not try_job or not try_job.completed or try_job.failed:
       return None
 
     if build_failure_type == failure_type.COMPILE:
+      if not try_job.compile_results:  # pragma: no cover.
+        return None
       return try_job.compile_results[-1].get('culprit', {}).get(step_name)
 
+    if not try_job.test_results:  # pragma: no cover.
+      return None
+
     if test_name is None:
       step_info = try_job.test_results[-1].get('culprit', {}).get(step_name)
       if not step_info or step_info.get('tests'):  # pragma: no cover.
         # TODO(chanli): For some steps like checkperms/sizes/etc, the culprit
         # finding try-job might have test-level results.
         return None
       return step_info
 
     task = WfSwarmingTask.Get(*try_job_key.split('/'), step_name=step_name)
     ref_name = (task.parameters.get('ref_name') if task and task.parameters
@@ skipping 87 matching lines @@
     logging.info('%d build failure(s), while %d are supported',
                  len(request.builds), len(supported_builds))
     try:
       _TriggerNewAnalysesOnDemand(supported_builds)
     except Exception:  # pragma: no cover.
       # If we fail to post a task to the task queue, we ignore and wait for next
       # request.
       logging.exception('Failed to trigger new analyses on demand.')
 
     return _BuildFailureAnalysisResultCollection(results=results)