[polymer] Merge of master into polymer10-migration

telemetry/telemetry/testing/browser_test_runner.py

Index: telemetry/telemetry/testing/browser_test_runner.py
diff --git a/telemetry/telemetry/testing/browser_test_runner.py b/telemetry/telemetry/testing/browser_test_runner.py
index 5a4dd4588f78f83ec6e2ecf7438349a52b3121a7..cea4e0e0c005b299e6523cbdb071030bb4bb6a7c 100644
--- a/telemetry/telemetry/testing/browser_test_runner.py
+++ b/telemetry/telemetry/testing/browser_test_runner.py
@@ -6,6 +6,7 @@ import argparse
 import inspect
 import json
 import re
+import time
 import unittest
 
 from telemetry.core import discover
@@ -15,18 +16,21 @@ from telemetry.testing import options_for_unittests
 from telemetry.testing import serially_executed_browser_test_case
 
 
-def ProcessCommandLineOptions(test_class, args):
+def ProcessCommandLineOptions(test_class, project_config, args):
   options = browser_options.BrowserFinderOptions()
   options.browser_type = 'any'
   parser = options.CreateParser(test_class.__doc__)
   test_class.AddCommandlineArgs(parser)
+  # Set the default chrome root variable. This is required for the
+  # Android browser finder to function properly.
+  parser.set_defaults(chrome_root=project_config.default_chrome_root)
   finder_options, positional_args = parser.parse_args(args)
   finder_options.positional_args = positional_args
   options_for_unittests.Push(finder_options)
   return finder_options
 
 
-def ValidateDistinctNames(browser_test_classes):
+def _ValidateDistinctNames(browser_test_classes):
   names_to_test_classes = {}
   for cl in browser_test_classes:
     name = cl.Name()
@@ -36,16 +40,16 @@ def ValidateDistinctNames(browser_test_classes):
     names_to_test_classes[name] = cl
 
 
-def GenerateTestMethod(based_method, args):
+def _GenerateTestMethod(based_method, args):
   return lambda self: based_method(self, *args)
 
 
 _INVALID_TEST_NAME_RE = re.compile(r'[^a-zA-Z0-9_]')
-def ValidateTestMethodname(test_name):
+def _ValidateTestMethodname(test_name):
   assert not bool(_INVALID_TEST_NAME_RE.search(test_name))
 
 
-def TestRangeForShard(total_shards, shard_index, num_tests):
+def _TestRangeForShard(total_shards, shard_index, num_tests):
   """Returns a 2-tuple containing the start (inclusive) and ending
   (exclusive) indices of the tests that should be run, given that
   |num_tests| tests are split across |total_shards| shards, and that
@@ -77,12 +81,85 @@ def TestRangeForShard(total_shards, shard_index, num_tests):
   return (num_earlier_tests, num_earlier_tests + tests_for_this_shard)
 
 
+def _MedianTestTime(test_times):
+  times = test_times.values()
+  times.sort()
+  if len(times) == 0:
+    return 0
+  halfLen = len(times) / 2
+  if len(times) % 2:
+    return times[halfLen]
+  else:
+    return 0.5 * (times[halfLen - 1] + times[halfLen])
+
+
+def _TestTime(test, test_times, default_test_time):
+  return test_times.get(test.shortName()) or default_test_time
+
+
+def _DebugShardDistributions(shards, test_times):
+  for i, s in enumerate(shards):
+    num_tests = len(s)
+    if test_times:
+      median = _MedianTestTime(test_times)
+      shard_time = 0.0
+      for t in s:
+        shard_time += _TestTime(t, test_times, median)
+      print 'shard %d: %d seconds (%d tests)' % (i, shard_time, num_tests)
+    else:
+      print 'shard %d: %d tests (unknown duration)' % (i, num_tests)
+
+
+def _SplitShardsByTime(test_cases, total_shards, test_times,
+                       debug_shard_distributions):
+  median = _MedianTestTime(test_times)
+  shards = []
+  for i in xrange(total_shards):
+    shards.append({'total_time': 0.0, 'tests': []})
+  test_cases.sort(key=lambda t: _TestTime(t, test_times, median),
+                  reverse=True)
+
+  # The greedy algorithm has been empirically tested on the WebGL 2.0
+  # conformance tests' times, and results in an essentially perfect
+  # shard distribution of 530 seconds per shard. In the same scenario,
+  # round-robin scheduling resulted in shard times spread between 502
+  # and 592 seconds, and the current alphabetical sharding resulted in
+  # shard times spread between 44 and 1591 seconds.
+
+  # Greedy scheduling. O(m*n), where m is the number of shards and n
+  # is the number of test cases.
+  for t in test_cases:
+    min_shard_index = 0
+    min_shard_time = None
+    for i in xrange(total_shards):
+      if min_shard_time is None or shards[i]['total_time'] < min_shard_time:
+        min_shard_index = i
+        min_shard_time = shards[i]['total_time']
+    shards[min_shard_index]['tests'].append(t)
+    shards[min_shard_index]['total_time'] += _TestTime(t, test_times, median)
+
+  res = [s['tests'] for s in shards]
+  if debug_shard_distributions:
+    _DebugShardDistributions(res, test_times)
+
+  return res
+
+
 _TEST_GENERATOR_PREFIX = 'GenerateTestCases_'
 
-def LoadTests(test_class, finder_options, filter_regex_str,
-              total_shards, shard_index):
+def _LoadTests(test_class, finder_options, filter_regex_str,
+               filter_tests_after_sharding,
+               total_shards, shard_index, test_times,
+               debug_shard_distributions):
   test_cases = []
-  filter_regex = re.compile(filter_regex_str)
+  real_regex = re.compile(filter_regex_str)
+  noop_regex = re.compile('')
+  if filter_tests_after_sharding:
+    filter_regex = noop_regex
+    post_filter_regex = real_regex
+  else:
+    filter_regex = real_regex
+    post_filter_regex = noop_regex
   for name, method in inspect.getmembers(
       test_class, predicate=inspect.ismethod):
     if name.startswith('test'):
@@ -101,14 +178,30 @@ def LoadTests(test_class, finder_options, filter_regex_str,
           name, based_method_name)
       based_method = getattr(test_class, based_method_name)
       for generated_test_name, args in method(finder_options):
-        ValidateTestMethodname(generated_test_name)
+        _ValidateTestMethodname(generated_test_name)
         if filter_regex.search(generated_test_name):
-          setattr(test_class, generated_test_name, GenerateTestMethod(
+          setattr(test_class, generated_test_name, _GenerateTestMethod(
               based_method, args))
           test_cases.append(test_class(generated_test_name))
-  test_cases.sort(key=lambda t: t.id())
-  test_range = TestRangeForShard(total_shards, shard_index, len(test_cases))
-  return test_cases[test_range[0]:test_range[1]]
+  if test_times:
+    # Assign tests to shards.
+    shards = _SplitShardsByTime(test_cases, total_shards, test_times,
+                                debug_shard_distributions)
+    return [t for t in shards[shard_index]
+            if post_filter_regex.search(t.shortName())]
+  else:
+    test_cases.sort(key=lambda t: t.shortName())
+    test_range = _TestRangeForShard(total_shards, shard_index, len(test_cases))
+    if debug_shard_distributions:
+      tmp_shards = []
+      for i in xrange(total_shards):
+        tmp_range = _TestRangeForShard(total_shards, i, len(test_cases))
+        tmp_shards.append(test_cases[tmp_range[0]:tmp_range[1]])
+      # Can edit the code to get 'test_times' passed in here for
+      # debugging and comparison purposes.
+      _DebugShardDistributions(tmp_shards, None)
+    return [t for t in test_cases[test_range[0]:test_range[1]]
+            if post_filter_regex.search(t.shortName())]
 
 
 class TestRunOptions(object):
@@ -120,11 +213,21 @@ class BrowserTestResult(unittest.TextTestResult):
   def __init__(self, *args, **kwargs):
     super(BrowserTestResult, self).__init__(*args, **kwargs)
     self.successes = []
+    self.times = {}
+    self._current_test_start_time = 0
 
   def addSuccess(self, test):
     super(BrowserTestResult, self).addSuccess(test)
     self.successes.append(test)
 
+  def startTest(self, test):
+    super(BrowserTestResult, self).startTest(test)
+    self._current_test_start_time = time.time()
+
+  def stopTest(self, test):
+    super(BrowserTestResult, self).stopTest(test)
+    self.times[test.shortName()] = (time.time() - self._current_test_start_time)
+
 
 def Run(project_config, test_run_options, args):
   binary_manager.InitDependencyManager(project_config.client_configs)
@@ -140,15 +243,31 @@ def Run(project_config, test_run_options, args):
       'this script is responsible for spawning all of the shards.)')
   parser.add_argument('--shard-index', default=0, type=int,
       help='Shard index (0..total_shards-1) of this test run.')
+  parser.add_argument(
+    '--filter-tests-after-sharding', default=False, action='store_true',
+    help=('Apply the test filter after tests are split for sharding. Useful '
+          'for reproducing bugs related to the order in which tests run.'))
+  parser.add_argument(
+      '--read-abbreviated-json-results-from', metavar='FILENAME',
+      action='store', help=(
+        'If specified, reads abbreviated results from that path in json form. '
+        'The file format is that written by '
+        '--write-abbreviated-json-results-to. This information is used to more '
+        'evenly distribute tests among shards.'))
+  parser.add_argument('--debug-shard-distributions',
+      action='store_true', default=False,
+      help='Print debugging information about the shards\' test distributions')
+
   option, extra_args = parser.parse_known_args(args)
 
   for start_dir in project_config.start_dirs:
     modules_to_classes = discover.DiscoverClasses(
         start_dir, project_config.top_level_dir,
-        base_class=serially_executed_browser_test_case.SeriallyBrowserTestCase)
+        base_class=serially_executed_browser_test_case.
+            SeriallyExecutedBrowserTestCase)
     browser_test_classes = modules_to_classes.values()
 
-  ValidateDistinctNames(browser_test_classes)
+  _ValidateDistinctNames(browser_test_classes)
 
   test_class = None
   for cl in browser_test_classes:
@@ -162,11 +281,19 @@ def Run(project_config, test_run_options, args):
         cl.Name() for cl in browser_test_classes)
     return 1
 
-  options = ProcessCommandLineOptions(test_class, extra_args)
+  options = ProcessCommandLineOptions(test_class, project_config, extra_args)
+
+  test_times = None
+  if option.read_abbreviated_json_results_from:
+    with open(option.read_abbreviated_json_results_from, 'r') as f:
+      abbr_results = json.load(f)
+      test_times = abbr_results.get('times')
 
   suite = unittest.TestSuite()
-  for test in LoadTests(test_class, options, option.test_filter,
-                        option.total_shards, option.shard_index):
+  for test in _LoadTests(test_class, options, option.test_filter,
+                         option.filter_tests_after_sharding,
+                         option.total_shards, option.shard_index,
+                         test_times, option.debug_shard_distributions):
     suite.addTest(test)
 
   results = unittest.TextTestRunner(
@@ -174,18 +301,28 @@ def Run(project_config, test_run_options, args):
       resultclass=BrowserTestResult).run(suite)
   if option.write_abbreviated_json_results_to:
     with open(option.write_abbreviated_json_results_to, 'w') as f:
-      json_results = {'failures': [], 'successes': [], 'valid': True}
+      json_results = {'failures': [], 'successes': [],
+                      'times': {}, 'valid': True}
       # Treat failures and errors identically in the JSON
       # output. Failures are those which cooperatively fail using
       # Python's unittest APIs; errors are those which abort the test
       # case early with an execption.
       failures = []
-      failures.extend(results.failures)
-      failures.extend(results.errors)
-      failures.sort(key=lambda entry: entry[0].id())
-      for (failed_test_case, _) in failures:
-        json_results['failures'].append(failed_test_case.id())
+      for fail, _ in results.failures + results.errors:
+        # When errors in thrown in individual test method or setUp or tearDown,
+        # fail would be an instance of unittest.TestCase.
+        if isinstance(fail, unittest.TestCase):
+          failures.append(fail.shortName())
+        else:
+          # When errors in thrown in setupClass or tearDownClass, an instance of
+          # _ErrorHolder is is placed in results.errors list. We use the id()
+          # as failure name in this case since shortName() is not available.
+          failures.append(fail.id())
+      failures = sorted(list(failures))
+      for failure_id in failures:
+        json_results['failures'].append(failure_id)
       for passed_test_case in results.successes:
-        json_results['successes'].append(passed_test_case.id())
+        json_results['successes'].append(passed_test_case.shortName())
+      json_results['times'].update(results.times)
       json.dump(json_results, f)
   return len(results.failures + results.errors)