In update-w3c-test-expectations, handle failure to fetch results.

third_party/WebKit/Tools/Scripts/webkitpy/w3c/update_w3c_test_expectations.py

 # Copyright 2016 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.
 
 """Functionality for adding TestExpectations lines and downloading baselines
 based on layout test failures in try jobs.
 
 This script is used as part of the w3c test auto-import process.
 """
 
+import logging
+
 from webkitpy.common.net.rietveld import Rietveld
-from webkitpy.common.net.buildbot import BuildBot
+from webkitpy.common.net.buildbot import BuildBot, Build
 from webkitpy.common.net.git_cl import GitCL
 from webkitpy.common.webkit_finder import WebKitFinder
 from webkitpy.w3c.test_parser import TestParser
 
+_log = logging.getLogger(__name__)
+
 
 def main(host):
+    # TODO(qyearsley): Add a "main" function to W3CExpectationsLineAdder
+    # and move most or all of this logic in there.
     host.initialize_scm()
     port = host.port_factory.get()
     expectations_file = port.path_to_generic_test_expectations_file()
     expectations_line_adder = W3CExpectationsLineAdder(host)
     issue_number = expectations_line_adder.get_issue_number()
     try_bots = expectations_line_adder.get_try_bots()
     rietveld = Rietveld(host.web)
     try_jobs = rietveld.latest_try_jobs(issue_number, try_bots)
     test_expectations = {}
     if not try_jobs:
@@ skipping 36 matching lines @@
                 }}
         return test_dict
 
     def get_failing_results_dict(self, buildbot, builder_name, build_number):
         """Returns a nested dict of failing test results.
 
         Retrieves a full list of layout test results from a builder result URL.
         Collects the builder name, platform and a list of tests that did not
         run as expected.
 
+        TODO(qyearsley): Rather than taking a BuildBot object, this should use
+        the Host's BuildBot object.
+
         Args:
+            buildbot: A BuildBot object.
             builder: A Builder object.
             build: A Build object.
 
         Returns:
             A dictionary with the structure: {
                 'key': {
                     'expected': 'TIMEOUT',
                     'actual': 'CRASH',
                     'bug': 'crbug.com/11111'
                 }
             }
+            If there are no failing results or no results could be fetched,
+            this will return an empty dict.
         """
-        results_url = buildbot.results_url(builder_name, build_number)
-        layout_test_results = buildbot.fetch_layout_test_results(results_url)
+        layout_test_results = buildbot.fetch_results(Build(builder_name, build_number))
+        if layout_test_results is None:
+            _log.warning('No results for builder %s, build %s', builder_name, build_number)
+            return {}
         platform = self._host.builders.port_name_for_builder_name(builder_name)
         result_list = layout_test_results.didnt_run_as_expected_results()
         failing_results_dict = self._generate_results_dict(platform, result_list)
         return failing_results_dict
 
     def merge_dicts(self, target, source, path=None):
         """Recursively merges nested dictionaries.
 
         Args:
             target: First dictionary, which is updated based on source.
@@ skipping 225 matching lines @@
                 for platform in tests_results[test_path].keys():
                     if tests_results[test_path][platform]['actual'] not in ['CRASH', 'TIMEOUT']:
                         del tests_results[test_path][platform]
                         tests_to_rebaseline.add(test_path)
         return list(tests_to_rebaseline), tests_results
 
     def is_js_test(self, webkit_finder, test_path):
         absolute_path = self._host.filesystem.join(webkit_finder.chromium_base(), test_path)
         test_parser = TestParser(absolute_path, self._host)
         return test_parser.is_jstest()