[Findit] Add more tests to improve code coverage.

appengine/findit/waterfall/detect_first_failure_pipeline.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 base64
 import json
 
 from common import constants
 from common.http_client_appengine import HttpClientAppengine as HttpClient
 from common.pipeline_wrapper import BasePipeline
@@ skipping 336 matching lines @@
 
     # Identifies swarming tests and saves isolated data to them.
     result = swarming_util.GetIsolatedDataForFailedBuild(
         master_name, builder_name, build_number, failed_steps,
         http_client)
     if not result:
       return
 
     for step_name, failed_step in failed_steps.iteritems():
       if not failed_step.get('list_isolated_data'):  # Non-swarming step.
-        continue
+        continue  # pragma: no cover.
 
       # Checks tests in one step and updates failed_step info if swarming.
       result = self._StartTestLevelCheckForFirstFailure(
           master_name, builder_name, build_number, step_name,
           failed_step, http_client)
 
       if result:  # pragma: no cover
         # Iterates backwards to get a more precise failed_steps info.
         self._UpdateFirstFailureOnTestLevel(
             master_name, builder_name, build_number, step_name,
@@ skipping 94 matching lines @@
 
     failure_info['builds'] = builds
     failure_info['failed_steps'] = failed_steps
 
     analysis = WfAnalysis.Get(master_name, builder_name, build_number)
     analysis.not_passed_steps = build_info.not_passed_steps
     analysis.build_failure_type = build_failure_type
     analysis.put()
 
     return failure_info