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

appengine/findit/waterfall/build_failure_analysis_pipelines.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.
 
 from datetime import datetime
 import logging
 
 from google.appengine.ext import ndb
 
 from common import appengine_util
 from common import constants
 from model import analysis_status
 from model.wf_analysis import WfAnalysis
-from waterfall import analyze_build_failure_pipeline
+from waterfall.analyze_build_failure_pipeline import AnalyzeBuildFailurePipeline
 
 
 @ndb.transactional
 def NeedANewAnalysis(
     master_name, builder_name, build_number, failed_steps,
     build_completed, force):
   """Checks status of analysis for the build and decides if a new one is needed.
 
   A WfAnalysis entity for the given build will be created if none exists.
   When a new analysis is needed, this function will create and save a WfAnalysis
@@ skipping 69 matching lines @@
     force_try_job (bool): Indicate whether or not a try job should be run or
         rerun as long as a corresponding try bot is configured.
     queue_name (str): The task queue to be used for pipeline tasks.
 
   Returns:
     A WfAnalysis instance.
   """
   if NeedANewAnalysis(
       master_name, builder_name, build_number, failed_steps,
       build_completed, force):
-    pipeline_job = analyze_build_failure_pipeline.AnalyzeBuildFailurePipeline(
+    pipeline_job = AnalyzeBuildFailurePipeline(
         master_name, builder_name, build_number, build_completed,
         force_try_job)
     # Explicitly run analysis in the backend module "waterfall-backend".
     # Note: Just setting the target in queue.yaml does NOT work for pipeline
     # when deployed to App Engine, but it does work in dev-server locally.
     # A possible reason is that pipeline will pick a default target if none is
     # specified explicitly, and the default target is used rather than the one
     # in the queue.yaml file, but this contradicts the documentation in
     # https://cloud.google.com/appengine/docs/python/taskqueue/tasks#Task.
     pipeline_job.target = appengine_util.GetTargetNameForModule(
         constants.WATERFALL_BACKEND)
     pipeline_job.start(queue_name=queue_name)
 
     logging.info('An analysis was scheduled for build %s, %s, %s: %s',
                  master_name, builder_name, build_number,
                  pipeline_job.pipeline_status_path())
 
   return WfAnalysis.Get(master_name, builder_name, build_number)