[Findit] Use unittest.mock for testing and create a shared method to mock pipeline.

appengine/findit/waterfall/analyze_build_failure_pipeline.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.
 
 from datetime import datetime
 
 from common import appengine_util
 from common.pipeline_wrapper import BasePipeline
 from common.pipeline_wrapper import pipeline
 from model import analysis_status
@@ skipping 19 matching lines @@
     self.master_name = master_name
     self.builder_name = builder_name
     self.build_number = build_number
 
   def _LogUnexpectedAborting(self, was_aborted):
     """Marks the WfAnalysis status as error, indicating that it was aborted.
 
     Args:
       was_aborted (bool): True if the pipeline was aborted, otherwise False.
     """
-    if was_aborted:
-      analysis = WfAnalysis.Get(
-          self.master_name, self.builder_name, self.build_number)
-      # Heuristic analysis could have already completed, while triggering the
-      # try job kept failing and lead to the abortion.
-      if analysis and not analysis.completed:
-        analysis.status = analysis_status.ERROR
-        analysis.result_status = None
-        analysis.put()
+    if not was_aborted:
+      return
+
+    analysis = WfAnalysis.Get(
+        self.master_name, self.builder_name, self.build_number)
+    # Heuristic analysis could have already completed, while triggering the
+    # try job kept failing and lead to the abortion.
+    if not analysis.completed:
+      analysis.status = analysis_status.ERROR
+      analysis.result_status = None
+      analysis.put()
 
   def finalized(self):
     self._LogUnexpectedAborting(self.was_aborted)
 
   def _ResetAnalysis(self, master_name, builder_name, build_number):
     analysis = WfAnalysis.Get(master_name, builder_name, build_number)
     analysis.pipeline_status_path = self.pipeline_status_path()
     analysis.status = analysis_status.RUNNING
     analysis.result_status = None
     analysis.start_time = datetime.utcnow()
@@ skipping 18 matching lines @@
         failure_info, change_logs, deps_info, signals, build_completed)
 
     with pipeline.InOrder():
       # Triggers swarming tasks when test failure happens.
       yield TriggerSwarmingTasksPipeline(
           master_name, builder_name, build_number, failure_info)
       # Checks if need a try job and starts one if yes.
       yield StartTryJobOnDemandPipeline(
           failure_info, signals, build_completed, force_rerun_try_job,
           heuristic_result)