# -*- coding: utf-8 -*-
# Copyright 2018 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Library for running Chrome OS tests."""

from __future__ import print_function

import datetime
import os
import sys

from chromite.cli.cros import cros_chrome_sdk
from chromite.lib import chrome_util
from chromite.lib import constants
from chromite.lib import cros_build_lib
from chromite.lib import cros_logging as logging
from chromite.lib import device
from chromite.lib import osutils
from chromite.lib import path_util
from chromite.lib import vm
from chromite.lib.xbuddy import xbuddy


assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'


class CrOSTest(object):
  """Class for running Chrome OS tests."""

  def __init__(self, opts):
    """Initialize CrOSTest.

    Args:
      opts: command line options.
    """
    self.start_time = datetime.datetime.utcnow()

    self.start_vm = opts.start_vm
    self.cache_dir = opts.cache_dir
    self.dryrun = opts.dryrun

    self.build = opts.build
    self.flash = opts.flash
    self.public_image = opts.public_image
    self.xbuddy = opts.xbuddy
    self.deploy = opts.deploy
    self.deploy_lacros = opts.deploy_lacros
    self.nostrip = opts.nostrip
    self.build_dir = opts.build_dir
    self.mount = opts.mount

    self.catapult_tests = opts.catapult_tests
    self.guest = opts.guest

    self.autotest = opts.autotest
    self.tast = opts.tast
    self.tast_vars = opts.tast_vars
    self.tast_total_shards = opts.tast_total_shards
    self.tast_shard_index = opts.tast_shard_index
    self.results_dir = opts.results_dir
    self.test_that_args = opts.test_that_args
    self.test_timeout = opts.test_timeout

    self.remote_cmd = opts.remote_cmd
    self.host_cmd = opts.host_cmd
    self.cwd = opts.cwd
    self.files = opts.files
    self.files_from = opts.files_from
    self.as_chronos = opts.as_chronos
    self.args = opts.args[1:] if opts.args else None

    self.results_src = opts.results_src
    self.results_dest_dir = opts.results_dest_dir
    self.save_snapshot_on_failure = opts.save_snapshot_on_failure

    self.chrome_test = opts.chrome_test
    if self.chrome_test:
      self.chrome_test_target = os.path.basename(opts.args[1])
      self.chrome_test_deploy_target_dir = '/usr/local/chrome_test'
    else:
      self.chrome_test_target = None
      self.chrome_test_deploy_target_dir = None
    self.staging_dir = None

    self._device = device.Device.Create(opts)

  def __del__(self):
    self._StopVM()

    logging.info('Time elapsed: %s',
                 datetime.datetime.utcnow() - self.start_time)

  def Run(self):
    """Start a VM, build/deploy, run tests, stop the VM."""
    if self._device.should_start_vm:
      self._StartVM()
    else:
      self._device.WaitForBoot()

    self._Build()
    self._Flash()
    self._Deploy()

    returncode = self._RunTests()

    self._StopVM()
    return returncode

  def _StartVM(self):
    """Start a VM if necessary.

    If --start-vm is specified, we launch a new VM, otherwise we use an
    existing VM.
    """
    if not self._device.should_start_vm:
      return

    if not self._device.IsRunning():
      self.start_vm = True

    if self.start_vm:
      self._device.Start()

  def _StopVM(self):
    """Stop the VM if necessary.

    If --start-vm was specified, we launched this VM, so we now stop it.
    """
    if self._device and self.start_vm:
      self._device.Stop()

  def _Build(self):
    """Build chrome."""
    if not self.build:
      return

    build_target = self.chrome_test_target or 'chromiumos_preflight'
    cros_build_lib.run(['autoninja', '-C', self.build_dir, build_target],
                       dryrun=self.dryrun)

  def _Flash(self):
    """Flash device."""
    if not self.flash:
      return

    if self.xbuddy:
      xbuddy_path = self.xbuddy.format(board=self._device.board)
    else:
      version = xbuddy.LATEST
      if path_util.DetermineCheckout().type != path_util.CHECKOUT_TYPE_REPO:
        # Try flashing to the full version of the board used in the Simple
        # Chrome SDK if it's present in the cache. Otherwise default to using
        # latest.
        cache = self.cache_dir or path_util.GetCacheDir()
        version = cros_chrome_sdk.SDKFetcher.GetCachedFullVersion(
            cache, self._device.board) or version
      suffix = ''
      if self.public_image:
        suffix = '-full'
      xbuddy_path = 'xbuddy://remote/%s%s/%s' % (
          self._device.board, suffix, version)

    # Only considers skipping flashing if it's NOT for lacros-chrome tests
    # because at this time, automated/CI tests can't assume that ash-chrome is
    # left in a clean state and lacros-chrome depends on ash-chrome.
    if not self.deploy_lacros:
      # Skip the flash if the device is already running the requested version.
      device_version = self._device.remote.version
      _, _, requested_version, _ = xbuddy.XBuddy.InterpretPath(xbuddy_path)
      # Split on the first "-" when comparing versions since xbuddy requires
      # the RX- prefix, but the device may not advertise it.
      if xbuddy.LATEST not in requested_version:
        if (requested_version == device_version or
            ('-' in requested_version and
             requested_version.split('-', 1)[1] == device_version)):
          logging.info(
              'Skipping the flash. Device running %s when %s was requested',
              device_version, xbuddy_path)
          return

    device_name = 'ssh://' + self._device.device
    if self._device.ssh_port:
      device_name += ':' + str(self._device.ssh_port)
    flash_cmd = [
        os.path.join(constants.CHROMITE_BIN_DIR, 'cros'),
        'flash',
        device_name,
        xbuddy_path,
        '--board', self._device.board,
        '--disable-rootfs-verification',
        '--clobber-stateful',
        '--clear-tpm-owner',
    ]
    cros_build_lib.run(flash_cmd, dryrun=self.dryrun)

  def _Deploy(self):
    """Deploy binary files to device."""
    if not self.build and not self.deploy and not self.deploy_lacros:
      return

    if self.chrome_test:
      self._DeployChromeTest()
    else:
      self._DeployChrome()

  def _DeployChrome(self):
    """Deploy lacros-chrome or ash-chrome."""
    deploy_cmd = [
        'deploy_chrome',
        '--force',
        '--build-dir',
        self.build_dir,
        '--process-timeout',
        '180',
    ]
    if self._device.ssh_port:
      deploy_cmd += [
          '--device',
          '%s:%d' % (self._device.device, self._device.ssh_port)
      ]
    else:
      deploy_cmd += ['--device', self._device.device]

    if self.cache_dir:
      deploy_cmd += ['--cache-dir', self.cache_dir]

    if self.deploy_lacros:
      # By default, deploying lacros-chrome modifies the /etc/chrome_dev.conf
      # file, which is desired behavior for local development, however, a
      # modified config file interferes with automated testing.
      deploy_cmd += ['--lacros', '--nostrip', '--skip-modifying-config-file']
    else:
      deploy_cmd.append('--deploy-test-binaries')
      if self._device.board:
        deploy_cmd += ['--board', self._device.board]
      if self.nostrip:
        deploy_cmd += ['--nostrip']
      if self.mount:
        deploy_cmd += ['--mount']

    cros_build_lib.run(deploy_cmd, dryrun=self.dryrun)
    self._device.WaitForBoot()

  def _DeployChromeTest(self):
    """Deploy chrome test binary and its runtime files to device."""
    src_dir = os.path.dirname(os.path.dirname(self.build_dir))
    self._DeployCopyPaths(src_dir, self.chrome_test_deploy_target_dir,
                          chrome_util.GetChromeTestCopyPaths(
                              self.build_dir, self.chrome_test_target))

  def _DeployCopyPaths(self, host_src_dir, remote_target_dir, copy_paths):
    """Deploy files in copy_paths to device.

    Args:
      host_src_dir: Source dir on the host that files in |copy_paths| are
                    relative to.
      remote_target_dir: Target dir on the remote device that the files in
                         |copy_paths| are copied to.
      copy_paths: A list of chrome_utils.Path of files to be copied.
    """
    with osutils.TempDir(set_global=True) as tempdir:
      self.staging_dir = tempdir
      strip_bin = None
      chrome_util.StageChromeFromBuildDir(
          self.staging_dir, host_src_dir, strip_bin, copy_paths=copy_paths)

      if self._device.remote.HasRsync():
        self._device.remote.CopyToDevice(
            '%s/' % os.path.abspath(self.staging_dir), remote_target_dir,
            mode='rsync', inplace=True, compress=True, debug_level=logging.INFO)
      else:
        self._device.remote.CopyToDevice(
            '%s/' % os.path.abspath(self.staging_dir), remote_target_dir,
            mode='scp', debug_level=logging.INFO)

  def _RunCatapultTests(self):
    """Run catapult tests matching a pattern using run_tests.

    Returns:
      cros_build_lib.CommandResult object.
    """

    browser = 'system-guest' if self.guest else 'system'
    return self._device.remote_run([
        'python',
        '/usr/local/telemetry/src/third_party/catapult/telemetry/bin/run_tests',
        '--browser=%s' % browser,
    ] + self.catapult_tests, stream_output=True)

  def _RunAutotest(self):
    """Run an autotest using test_that.

    Returns:
      cros_build_lib.CommandResult object.
    """
    cmd = ['test_that']
    if self._device.board:
      cmd += ['--board', self._device.board]
    if self.results_dir:
      cmd += ['--results_dir', path_util.ToChrootPath(self.results_dir)]
    if self._device.private_key:
      cmd += ['--ssh_private_key',
              path_util.ToChrootPath(self._device.private_key)]
    if self._device.log_level == 'debug':
      cmd += ['--debug']
    if self.test_that_args:
      cmd += self.test_that_args[1:]
    cmd += [
        '--no-quickmerge',
        '--ssh_options', '-F /dev/null -i /dev/null',
    ]
    if self._device.ssh_port:
      cmd += ['%s:%d' % (self._device.device, self._device.ssh_port)]
    else:
      cmd += [self._device.device]
    cmd += self.autotest
    return cros_build_lib.run(cmd, dryrun=self.dryrun, enter_chroot=True)

  def _RunTastTests(self):
    """Run Tast tests.

    Returns:
      cros_build_lib.CommandResult object.
    """
    # Try using the Tast binaries that the SimpleChrome SDK downloads
    # automatically.
    tast_cache_dir = cros_chrome_sdk.SDKFetcher.GetCachePath(
        'chromeos-base', self.cache_dir, self._device.board)
    if tast_cache_dir:
      tast_bin_dir = os.path.join(tast_cache_dir, 'tast-cmd', 'usr', 'bin')
      cmd = [os.path.join(tast_bin_dir, 'tast')]
      need_chroot = False
    else:
      # Silently fall back to using the chroot if there's no SimpleChrome SDK
      # present.
      cmd = ['tast']
      need_chroot = True

    if self._device.log_level == 'debug':
      cmd += ['-verbose']
    cmd += ['run', '-build=false', '-waituntilready',]
    # If the tests are not informational, then fail on test failure.
    # TODO(dhanyaganesh@): Make this less hack-y crbug.com/1034403.
    if '!informational' in self.tast[0]:
      cmd += ['-failfortests']
    if not need_chroot:
      # The test runner needs to be pointed to the location of the test files
      # when we're using those in the SimpleChrome cache.
      remote_runner_path = os.path.join(tast_bin_dir, 'remote_test_runner')
      remote_bundle_dir = os.path.join(
          tast_cache_dir, 'tast-remote-tests-cros', 'usr', 'libexec', 'tast',
          'bundles', 'remote')
      remote_data_dir = os.path.join(
          tast_cache_dir, 'tast-remote-tests-cros', 'usr', 'share', 'tast',
          'data')
      private_key = (self._device.private_key or
                     self._device.remote.GetAgent().private_key)
      assert private_key, 'ssh private key not found.'
      cmd += [
          '-remoterunner=%s' % remote_runner_path,
          '-remotebundledir=%s' % remote_bundle_dir,
          '-remotedatadir=%s' % remote_data_dir,
          '-ephemeraldevserver=true',
          '-keyfile',
          private_key,
      ]
      # Tast may make calls to gsutil during the tests. If we're outside the
      # chroot, we may not have gsutil on PATH. So push chromite's copy of
      # gsutil onto path during the test.
      gsutil_dir = constants.CHROMITE_SCRIPTS_DIR
      extra_env = {'PATH': os.environ.get('PATH', '') + ':' + gsutil_dir}
    else:
      extra_env = None

    if self.test_timeout > 0:
      cmd += ['-timeout=%d' % self.test_timeout]
    # This flag is needed when running Tast tests on VMs. Note that this check
    # is only true if we're handling VM start-up/tear-down ourselves for the
    # duration of the test. If the caller has already launched a VM themselves
    # and has pointed the '--device' arg at it, this check will be false.
    if self._device.should_start_vm:
      cmd += ['-extrauseflags=tast_vm']
    if self.results_dir:
      results_dir = self.results_dir
      if need_chroot:
        results_dir = path_util.ToChrootPath(self.results_dir)
      cmd += ['-resultsdir', results_dir]
    if self.tast_vars:
      cmd += ['-var=%s' % v for v in self.tast_vars]
    if self.tast_total_shards:
      cmd += [
          '-totalshards=%d' % self.tast_total_shards,
          '-shardindex=%d' % self.tast_shard_index
      ]
    if self._device.ssh_port:
      cmd += ['%s:%d' % (self._device.device, self._device.ssh_port)]
    else:
      cmd += [self._device.device]
    cmd += self.tast
    return cros_build_lib.run(
        cmd,
        dryrun=self.dryrun,
        extra_env=extra_env,
        # Don't raise an exception if the command fails.
        check=False,
        enter_chroot=need_chroot and not cros_build_lib.IsInsideChroot())

  def _RunTests(self):
    """Run tests.

    Run user-specified tests, catapult tests, tast tests, autotest, or the
    default, vm_sanity.

    Returns:
      Command execution return code.
    """
    if self.remote_cmd:
      result = self._RunDeviceCmd()
    elif self.host_cmd:
      extra_env = {}
      if self.build_dir:
        extra_env['CHROMIUM_OUTPUT_DIR'] = self.build_dir
      # Don't raise an exception if the command fails.
      result = cros_build_lib.run(
          self.args, check=False, dryrun=self.dryrun, extra_env=extra_env)
    elif self.catapult_tests:
      result = self._RunCatapultTests()
    elif self.autotest:
      result = self._RunAutotest()
    elif self.tast:
      result = self._RunTastTests()
    elif self.chrome_test:
      result = self._RunChromeTest()
    else:
      result = self._device.remote_run(
          ['/usr/local/autotest/bin/vm_sanity.py'], stream_output=True)

    self._MaybeSaveVMImage(result)
    self._FetchResults()

    name = self.args[0] if self.args else 'Test process'
    logging.info('%s exited with status code %d.', name, result.returncode)

    return result.returncode

  def _MaybeSaveVMImage(self, result):
    """Tells the VM to save its image on shutdown if the test failed.

    Args:
      result: A cros_build_lib.CommandResult object from a test run.
    """
    if not self._device.should_start_vm or not self.save_snapshot_on_failure:
      return
    if not result.returncode:
      return
    osutils.SafeMakedirs(self.results_dest_dir)
    self._device.SaveVMImageOnShutdown(self.results_dest_dir)

  def _FetchResults(self):
    """Fetch results files/directories."""
    if not self.results_src:
      return
    osutils.SafeMakedirs(self.results_dest_dir)
    for src in self.results_src:
      logging.info('Fetching %s to %s', src, self.results_dest_dir)
      self._device.remote.CopyFromDevice(src=src, dest=self.results_dest_dir,
                                         mode='scp', debug_level=logging.INFO)

  def _RunDeviceCmd(self):
    """Run a command on the device.

    Copy src files to /usr/local/cros_test/, change working directory to
    self.cwd, run the command in self.args, and cleanup.

    Returns:
      cros_build_lib.CommandResult object.
    """
    DEST_BASE = '/usr/local/cros_test'
    files = FileList(self.files, self.files_from)
    # Copy files, preserving the directory structure.
    copy_paths = []
    for f in files:
      is_exe = os.path.isfile(f) and os.access(f, os.X_OK)
      has_exe = False
      if os.path.isdir(f):
        if not f.endswith('/'):
          f += '/'
        for sub_dir, _, sub_files in os.walk(f):
          for sub_file in sub_files:
            if os.access(os.path.join(sub_dir, sub_file), os.X_OK):
              has_exe = True
              break
          if has_exe:
            break
      copy_paths.append(chrome_util.Path(f, exe=is_exe or has_exe))
    if copy_paths:
      self._DeployCopyPaths(os.getcwd(), DEST_BASE, copy_paths)

    # Make cwd an absolute path (if it isn't one) rooted in DEST_BASE.
    cwd = self.cwd
    if files and not (cwd and os.path.isabs(cwd)):
      cwd = os.path.join(DEST_BASE, cwd) if cwd else DEST_BASE
      self._device.remote_run(['mkdir', '-p', cwd])

    if self.as_chronos:
      # This authorizes the test ssh keys with chronos.
      self._device.remote_run(['cp', '-r', '/root/.ssh/',
                               '/home/chronos/user/'])
      if files:
        # The trailing ':' after the user also changes the group to the user's
        # primary group.
        self._device.remote_run(['chown', '-R', 'chronos:', DEST_BASE])

    user = 'chronos' if self.as_chronos else None
    if cwd:
      # Run the remote command with cwd.
      cmd = 'cd %s && %s' % (cwd, ' '.join(self.args))
      # Pass shell=True because of && in the cmd.
      result = self._device.remote_run(cmd, stream_output=True, shell=True,
                                       remote_user=user)
    else:
      result = self._device.remote_run(self.args, stream_output=True,
                                       remote_user=user)

    # Cleanup.
    if files:
      self._device.remote_run(['rm', '-rf', DEST_BASE])

    return result

  def _RunChromeTest(self):
    # Stop UI in case the test needs to grab GPU.
    self._device.remote_run('stop ui')

    # Send a user activity ping to powerd to light up the display.
    self._device.remote_run(['dbus-send', '--system', '--type=method_call',
                             '--dest=org.chromium.PowerManager',
                             '/org/chromium/PowerManager',
                             'org.chromium.PowerManager.HandleUserActivity',
                             'int32:0'])

    # Run test.
    chrome_src_dir = os.path.dirname(os.path.dirname(self.build_dir))
    test_binary = os.path.relpath(
        os.path.join(self.build_dir, self.chrome_test_target), chrome_src_dir)
    test_args = self.args[1:]
    command = 'cd %s && su chronos -c -- "%s %s"' % \
        (self.chrome_test_deploy_target_dir, test_binary, ' '.join(test_args))
    result = self._device.remote_run(command, stream_output=True)
    return result


def ParseCommandLine(argv):
  """Parse the command line.

  Args:
    argv: Command arguments.

  Returns:
    List of parsed options for CrOSTest.
  """

  parser = vm.VM.GetParser()
  parser.add_argument('--start-vm', action='store_true', default=False,
                      help='Start a new VM before running tests.')
  parser.add_argument('--catapult-tests', nargs='+',
                      help='Catapult test pattern to run, passed to run_tests.')
  parser.add_argument('--autotest', nargs='+',
                      help='Autotest test pattern to run, passed to test_that.')
  parser.add_argument('--tast', nargs='+',
                      help='Tast test pattern to run, passed to tast. '
                      'See go/tast-running for patterns.')
  parser.add_argument('--tast-var', dest='tast_vars', action='append',
                      help='Runtime variables for Tast tests, and the format '
                      'are expected to be "key=value" pairs.')
  parser.add_argument('--tast-shard-index', type=int, default=0,
                      help='Shard index to use when running Tast tests.')
  parser.add_argument('--tast-total-shards', type=int, default=0,
                      help='Total number of shards when running Tast tests.')
  parser.add_argument('--chrome-test', action='store_true', default=False,
                      help='Run chrome test on device. The first arg in the '
                      'remote command should be the test binary name, such as '
                      'interactive_ui_tests. It is used for building and '
                      'collecting runtime deps files.')
  parser.add_argument('--guest', action='store_true', default=False,
                      help='Run tests in incognito mode.')
  parser.add_argument('--build', action='store_true', default=False,
                      help='Before running tests, build chrome using ninja, '
                      '--build-dir must be specified.')
  parser.add_argument('--build-dir', type='path',
                      help='Directory for building and deploying chrome.')
  parser.add_argument('--flash', action='store_true', default=False,
                      help='Before running tests, flash the device.')
  parser.add_argument('--public-image', action='store_true', default=False,
                      help='Flash with a public image.')
  parser.add_argument('--xbuddy',
                      help='xbuddy link to use for flashing the device. Will '
                      "default to the board's version used in the cros "
                      'chrome-sdk if available, or "latest" otherwise.')
  parser.add_argument('--deploy-lacros', action='store_true', default=False,
                      help='Before running tests, deploy lacros-chrome, '
                      '--build-dir must be specified.')
  parser.add_argument('--deploy', action='store_true', default=False,
                      help='Before running tests, deploy ash-chrome, '
                      '--build-dir must be specified.')
  parser.add_argument('--nostrip', action='store_true', default=False,
                      help="Don't strip symbols from binaries if deploying.")
  parser.add_argument('--mount', action='store_true', default=False,
                      help='Deploy ash-chrome to the default target directory '
                      'and bind it to the default mount directory. Useful for '
                      'large ash-chrome binaries.')
  # type='path' converts a relative path for cwd into an absolute one on the
  # host, which we don't want.
  parser.add_argument('--cwd', help='Change working directory. '
                      'An absolute path or a path relative to CWD on the host.')
  parser.add_argument('--files', default=[], action='append',
                      help='Files to scp to the device.')
  parser.add_argument('--files-from', type='path',
                      help='File with list of files to copy.')
  parser.add_argument('--results-src', default=[], action='append',
                      help='Files/Directories to copy from '
                      'the device into CWD after running the test.')
  parser.add_argument('--results-dest-dir', type='path',
                      help='Destination directory to copy results to.')
  parser.add_argument('--remote-cmd', action='store_true', default=False,
                      help='Run a command on the device.')
  parser.add_argument('--as-chronos', action='store_true',
                      help='Runs the remote test as the chronos user on '
                           'the device. Only supported for --remote-cmd tests. '
                           'Runs as root if not set.')
  parser.add_argument('--host-cmd', action='store_true', default=False,
                      help='Run a command on the host.')
  parser.add_argument('--results-dir', type='path',
                      help='Autotest results directory.')
  parser.add_argument('--test_that-args', action='append_option_value',
                      help='Args to pass directly to test_that for autotest.')
  parser.add_argument('--test-timeout', type=int, default=0,
                      help='Timeout for running all tests (for --tast).')
  parser.add_argument('--save-snapshot-on-failure', action='store_true',
                      default=False,
                      help='Save a snapshot of the VM on test failure to '
                           'results-dest-dir.')

  opts = parser.parse_args(argv)

  if opts.device and opts.device.port and opts.ssh_port:
    parser.error('Must not specify SSH port via both --ssh-port and --device.')

  if opts.chrome_test:
    if not opts.args:
      parser.error('Must specify a test command with --chrome-test')

    if not opts.build_dir:
      opts.build_dir = os.path.dirname(opts.args[1])

  if opts.build or opts.deploy or opts.deploy_lacros:
    if not opts.build_dir:
      parser.error('Must specify --build-dir with --build or --deploy.')
    if not os.path.isdir(opts.build_dir):
      parser.error('%s is not a directory.' % opts.build_dir)

  if opts.tast_vars and not opts.tast:
    parser.error('--tast-var is only applicable to Tast tests.')

  if opts.deploy and opts.deploy_lacros:
    parser.error('Cannot deploy lacros-chrome and ash-chrome at the same time.')

  if opts.results_src:
    for src in opts.results_src:
      if not os.path.isabs(src):
        parser.error('results-src must be absolute.')
    if not opts.results_dest_dir:
      parser.error('results-dest-dir must be specified with results-src.')
  if opts.results_dest_dir:
    if not opts.results_src:
      parser.error('results-src must be specified with results-dest-dir.')
    if os.path.isfile(opts.results_dest_dir):
      parser.error('results-dest-dir %s is an existing file.'
                   % opts.results_dest_dir)

  if opts.save_snapshot_on_failure and not opts.results_dest_dir:
    parser.error('Must specify results-dest-dir with save-snapshot-on-failure')

  # Ensure command is provided. For e.g. to copy out to the device and run
  # out/unittest:
  # cros_run_test --files out --cwd out --cmd -- ./unittest
  # Treat --cmd as --remote-cmd.
  opts.remote_cmd = opts.remote_cmd or opts.cmd
  if (opts.remote_cmd or opts.host_cmd) and len(opts.args) < 2:
    parser.error('Must specify test command to run.')
  if opts.as_chronos and not opts.remote_cmd:
    parser.error('as-chronos only supported when running test commands.')
  # Verify additional args.
  if opts.args:
    if not opts.remote_cmd and not opts.host_cmd and not opts.chrome_test:
      parser.error('Additional args may be specified with either '
                   '--remote-cmd or --host-cmd or --chrome-test: %s' %
                   opts.args)
    if opts.args[0] != '--':
      parser.error("Additional args must start with '--': %s" % opts.args)

  # Verify CWD.
  if opts.cwd:
    if opts.cwd.startswith('..'):
      parser.error('cwd cannot start with ..')
    if not os.path.isabs(opts.cwd) and not opts.files and not opts.files_from:
      parser.error('cwd must be an absolute path if '
                   '--files or --files-from is not specified')

  # Verify files.
  if opts.files_from:
    if opts.files:
      parser.error('--files and --files-from cannot both be specified')
    if not os.path.isfile(opts.files_from):
      parser.error('%s is not a file' % opts.files_from)
  files = FileList(opts.files, opts.files_from)
  for f in files:
    if os.path.isabs(f):
      parser.error('%s should be a relative path' % f)
    # Restrict paths to under CWD on the host. See crbug.com/829612.
    if f.startswith('..'):
      parser.error('%s cannot start with ..' % f)
    if not os.path.exists(f):
      parser.error('%s does not exist' % f)

  # Verify Tast.
  if opts.tast_shard_index or opts.tast_total_shards:
    if not opts.tast:
      parser.error('Can only specify --tast-total-shards and '
                   '--tast-shard-index with --tast.')
    if opts.tast_shard_index >= opts.tast_total_shards:
      parser.error('Shard index must be < total shards.')

  return opts


def FileList(files, files_from):
  """Get list of files from command line args --files and --files-from.

  Args:
    files: files specified directly on the command line.
    files_from: files specified in a file.

  Returns:
    Contents of files_from if it exists, otherwise files.
  """
  if files_from and os.path.isfile(files_from):
    with open(files_from) as f:
      files = [line.rstrip() for line in f]
  return files