Implement --browser=<perf trybot>

tools/telemetry/telemetry/unittest/run_tests.py

 # Copyright 2012 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 json
 import logging
+import StringIO
 import unittest
+import urllib2
 
 from telemetry import decorators
 from telemetry.core import browser_finder
 from telemetry.core import browser_options
 from telemetry.core import command_line
 from telemetry.core import discover
 from telemetry.unittest import json_results
 from telemetry.unittest import progress_reporter
 
 
@@ skipping 86 matching lines @@
       return func(*args, **kwargs)
     finally:
       # Restore logging level, which may be changed in parser.parse_args.
       logging.getLogger().setLevel(logging_level)
 
   return _LoggingRestoreWrapper
 
 
 config = None
 
+# pylint: disable=W0613
+def stuburlopen(url):
+  assert not hasattr(stuburlopen, 'called')
+  setattr(stuburlopen, 'called', 1)
+  return StringIO.StringIO(json.dumps({'builders':{
+      'android_nexus4_perf_bisect': 'stuff',
+      'mac_10_9_perf_bisect': 'otherstuff',
+      'win_perf_bisect_builder': 'not a trybot',
+  }}))
+
 
 class RunTestsCommand(command_line.OptparseCommand):
   """Run unit tests"""
 
   usage = '[test_name ...] [<options>]'
 
   @classmethod
   def CreateParser(cls):
     options = browser_options.BrowserFinderOptions()
     options.browser_type = 'any'
@@ skipping 75 matching lines @@
                                possible_browser, args.positional_args,
                                args.exact_test_filter, args.run_disabled_tests)
     runner = progress_reporter.TestRunner()
     result = runner.run(test_suite, config.progress_reporters,
                         args.repeat_count, args)
     return test_suite, result
 
   @classmethod
   @RestoreLoggingLevel
   def main(cls, args=None):
+    urllib2.urlopen = stuburlopen
     return super(RunTestsCommand, cls).main(args)

[sullivan, 2014/08/15 14:58:37]

There's one big problem with this CL: the unit tests end up invoking FindBrowser
which calls FindAllBrowserTypes() which calls
trybot_browser_finder.FindAllBrowserTypes() which pings the buildbot JSON url.

I made this ugly hack to demonstrate that decorators.Cache is working correctly:
urllib.urlopen() gets called exactly once when running all the unit tests. But
mocking out url opens for my trybot_browser_finder_unittest in run_tests is
awful. Is there a better way to do this?