Run the webkit layout tests under swarming on linux_chromium_rel_ng.

testing/scripts/run_isolated_script_test.py

+#!/usr/bin/env python
+# Copyright 2015 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.
+
+"""Runs a script that can run as an isolate (or not).
+
+The main requirement is that
+
+  --isolated-script-test-output=[FILENAME]
+
+is passed on the command line to run_isolated_script_tests. This gets
+remapped to the command line argument --write-full-results-to.
+
+json is written to that file in the format produced by
+common.parse_common_test_results.
+
+For compatibility with //base/test/launcher-based tests, the script
+will also remap the env vars GTEST_TOTAL_SHARDS and GTEST_SHARD_INDEX
+to the command line arguments --total-shards and --shard-index.
+
+This script is intended to be the base command invoked by the isolate,
+followed by a subsequent Python script. It could be generalized to
+invoke an arbitrary executable.
+"""
+
+import argparse
+import json
+import os
+import pprint
+import sys
+
+
+import common
+
+# Add src/testing/ into sys.path for importing xvfb.
+sys.path.append(os.path.join(os.path.dirname(__file__), '..'))
+import xvfb
+
+
+def main():
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--isolated-script-test-output', type=str,
+                      required=True)
+  parser.add_argument('--shards', type=int, help='number of shards')
+  parser.add_argument('--xvfb', help='start xvfb', action='store_true')
+
+  # This argument is ignored for now.
+  parser.add_argument('--isolated-script-test-chartjson-output', type=str)
+
+  args, rest_args = parser.parse_known_args()
+
+  sharding_args, env = _remap_gtest_env_vars(os.environ)
+
+  cmd = [sys.executable] + rest_args + sharding_args
+  cmd += ['--write-full-results-to', args.isolated_script_test_output]
+  if args.xvfb:
+    return xvfb.run_executable(cmd, env)
+  else:
+    return common.run_command(cmd, env=env)
+
+
+def _remap_gtest_env_vars(orig_env):

[mithro, 2017/01/31 23:51:42]

run_webkit_tests.py already supports these GTEST arguments,
----
src/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests$ grep -n GTEST
run_webkit_tests.py
549:        if not options.total_shards and 'GTEST_TOTAL_SHARDS' in
port.host.environ:
550:            options.total_shards =
int(port.host.environ['GTEST_TOTAL_SHARDS']) + 1
551:        if not options.shard_index and 'GTEST_SHARD_INDEX' in
port.host.environ:
552:            options.shard_index =
int(port.host.environ['GTEST_SHARD_INDEX'])
-----

I think we should push for everything to understand this environment natively?

[Dirk Pranke, 2017/02/01 01:32:51]

I think both maruel@ and I consider the support for these env vars to be a
misfeature, so, that would not be my vote, no :).

+  total_shards = None
+  shard_index = None
+  env = orig_env.copy()
+  if 'GTEST_TOTAL_SHARDS' in env:
+    total_shards = int(env['GTEST_TOTAL_SHARDS'])
+    del env['GTEST_TOTAL_SHARDS']
+  if 'GTEST_SHARD_INDEX' in env:
+    shard_index = int(env['GTEST_SHARD_INDEX'])
+    del env['GTEST_SHARD_INDEX']
+  sharding_args = []
+  if total_shards is not None and shard_index is not None:
+    sharding_args = [
+      '--total-shards=%d' % total_shards,
+      '--shard-index=%d' % shard_index
+    ]
+  return sharding_args, env
+
+
+
+# This is not really a "script test" so does not need to manually add
+# any additional compile targets.
+def main_compile_targets(args):
+  json.dump([], args.output)
+
+
+if __name__ == '__main__':
+  # Conform minimally to the protocol defined by ScriptTest.
+  if 'compile_targets' in sys.argv:
+    funcs = {
+      'run': None,
+      'compile_targets': main_compile_targets,
+    }
+    sys.exit(common.run_script(sys.argv[1:], funcs))
+  sys.exit(main())