dev/devicelab/lib/framework/utils.dart - mirrors/flutter - Git at Google

 // Copyright (c) 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.

 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:math' as math;

 import 'package:args/args.dart';
 import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path;
 import 'package:process/process.dart';
 import 'package:stack_trace/stack_trace.dart';

 import 'adb.dart';

 /// Virtual current working directory, which affect functions, such as [exec].
 String cwd = Directory.current.path;

 List<ProcessInfo> _runningProcesses = <ProcessInfo>[];
 ProcessManager _processManager = const LocalProcessManager();

 class ProcessInfo {
   ProcessInfo(this.command, this.process);

   final DateTime startTime = new DateTime.now();
   final String command;
   final Process process;

   @override
   String toString() {
     return '''
   command : $command
   started : $startTime
   pid     : ${process.pid}
 '''
         .trim();
   }
 }

 /// Result of a health check for a specific parameter.
 class HealthCheckResult {
   HealthCheckResult.success([this.details]) : succeeded = true;
   HealthCheckResult.failure(this.details) : succeeded = false;
   HealthCheckResult.error(dynamic error, dynamic stackTrace)
       : succeeded = false,
         details = 'ERROR: $error${'\n$stackTrace' ?? ''}';

   final bool succeeded;
   final String details;

   @override
   String toString() {
     final StringBuffer buf = new StringBuffer(succeeded ? 'succeeded' : 'failed');
     if (details != null && details.trim().isNotEmpty) {
       buf.writeln();
       // Indent details by 4 spaces
       for (String line in details.trim().split('\n')) {
         buf.writeln('    $line');
       }
     }
     return '$buf';
   }
 }

 class BuildFailedError extends Error {
   BuildFailedError(this.message);

   final String message;

   @override
   String toString() => message;
 }

 void fail(String message) {
   throw new BuildFailedError(message);
 }

 void rm(FileSystemEntity entity) {
   if (entity.existsSync())
     entity.deleteSync();
 }

 /// Remove recursively.
 void rmTree(FileSystemEntity entity) {
   if (entity.existsSync())
     entity.deleteSync(recursive: true);
 }

 List<FileSystemEntity> ls(Directory directory) => directory.listSync();

 Directory dir(String path) => new Directory(path);

 File file(String path) => new File(path);

 void copy(File sourceFile, Directory targetDirectory, {String name}) {
   final File target = file(
       path.join(targetDirectory.path, name ?? path.basename(sourceFile.path)));
   target.writeAsBytesSync(sourceFile.readAsBytesSync());
 }

 void recursiveCopy(Directory source, Directory target) {
   if (!target.existsSync())
     target.createSync();

   for (FileSystemEntity entity in source.listSync(followLinks: false)) {
     final String name = path.basename(entity.path);
     if (entity is Directory)
       recursiveCopy(entity, new Directory(path.join(target.path, name)));
     else if (entity is File) {
       final File dest = new File(path.join(target.path, name));
       dest.writeAsBytesSync(entity.readAsBytesSync());
     }
   }
 }

 FileSystemEntity move(FileSystemEntity whatToMove,
     {Directory to, String name}) {
   return whatToMove
       .renameSync(path.join(to.path, name ?? path.basename(whatToMove.path)));
 }

 /// Equivalent of `mkdir directory`.
 void mkdir(Directory directory) {
   directory.createSync();
 }

 /// Equivalent of `mkdir -p directory`.
 void mkdirs(Directory directory) {
   directory.createSync(recursive: true);
 }

 bool exists(FileSystemEntity entity) => entity.existsSync();

 void section(String title) {
   title = '╡ ••• $title ••• ╞';
   final String line = '═' * math.max((80 - title.length) ~/ 2, 2);
   String output = '$line$title$line';
   if (output.length == 79)
     output += '═';
   print('\n\n$output\n');
 }

 Future<String> getDartVersion() async {
   // The Dart VM returns the version text to stderr.
   final ProcessResult result = _processManager.runSync(<String>[dartBin, '--version']);
   String version = result.stderr.trim();

   // Convert:
   //   Dart VM version: 1.17.0-dev.2.0 (Tue May  3 12:14:52 2016) on "macos_x64"
   // to:
   //   1.17.0-dev.2.0
   if (version.contains('('))
     version = version.substring(0, version.indexOf('(')).trim();
   if (version.contains(':'))
     version = version.substring(version.indexOf(':') + 1).trim();

   return version.replaceAll('"', "'");
 }

 Future<String> getCurrentFlutterRepoCommit() {
   if (!dir('${flutterDirectory.path}/.git').existsSync()) {
     return null;
   }

   return inDirectory(flutterDirectory, () {
     return eval('git', <String>['rev-parse', 'HEAD']);
   });
 }

 Future<DateTime> getFlutterRepoCommitTimestamp(String commit) {
   // git show -s --format=%at 4b546df7f0b3858aaaa56c4079e5be1ba91fbb65
   return inDirectory(flutterDirectory, () async {
     final String unixTimestamp = await eval('git', <String>[
       'show',
       '-s',
       '--format=%at',
       commit,
     ]);
     final int secondsSinceEpoch = int.parse(unixTimestamp);
     return new DateTime.fromMillisecondsSinceEpoch(secondsSinceEpoch * 1000);
   });
 }

 /// Starts a subprocess.
 ///
 /// The first argument is the full path to the executable to run.
 ///
 /// The second argument is the list of arguments to provide on the command line.
 /// This argument can be null, indicating no arguments (same as the empty list).
 ///
 /// The `environment` argument can be provided to configure environment variables
 /// that will be made available to the subprocess. The `BOT` environment variable
 /// is always set and overrides any value provided in the `environment` argument.
 /// The `isBot` argument controls the value of the `BOT` variable. It will either
 /// be "true", if `isBot` is true (the default), or "false" if it is false.
 ///
 /// The `BOT` variable is in particular used by the `flutter` tool to determine
 /// how verbose to be and whether to enable analytics by default.
 ///
 /// The working directory can be provided using the `workingDirectory` argument.
 /// By default it will default to the current working directory (see [cwd]).
 ///
 /// Information regarding the execution of the subprocess is printed to the
 /// console.
 ///
 /// The actual process executes asynchronously. A handle to the subprocess is
 /// returned in the form of a [Future] that completes to a [Process] object.
 Future<Process> startProcess(
   String executable,
   List<String> arguments, {
   Map<String, String> environment,
   bool isBot = true, // set to false to pretend not to be on a bot (e.g. to test user-facing outputs)
   String workingDirectory,
 }) async {
   assert(isBot != null);
   final String command = '$executable ${arguments?.join(" ") ?? ""}';
   print('\nExecuting: $command');
   environment ??= <String, String>{};
   environment['BOT'] = isBot ? 'true' : 'false';
   final Process process = await _processManager.start(
     <String>[executable]..addAll(arguments),
     environment: environment,
     workingDirectory: workingDirectory ?? cwd,
   );
   final ProcessInfo processInfo = new ProcessInfo(command, process);
   _runningProcesses.add(processInfo);

   process.exitCode.then((int exitCode) {
     print('exitcode: $exitCode');
     _runningProcesses.remove(processInfo);
   });

   return process;
 }

 Future<Null> forceQuitRunningProcesses() async {
   if (_runningProcesses.isEmpty)
     return;

   // Give normally quitting processes a chance to report their exit code.
   await new Future<Null>.delayed(const Duration(seconds: 1));

   // Whatever's left, kill it.
   for (ProcessInfo p in _runningProcesses) {
     print('Force quitting process:\n$p');
     if (!p.process.kill()) {
       print('Failed to force quit process');
     }
   }
   _runningProcesses.clear();
 }

 /// Executes a command and returns its exit code.
 Future<int> exec(
   String executable,
   List<String> arguments, {
   Map<String, String> environment,
   bool canFail = false,
 }) async {
   final Process process = await startProcess(executable, arguments, environment: environment);

   final Completer<Null> stdoutDone = new Completer<Null>();
   final Completer<Null> stderrDone = new Completer<Null>();
   process.stdout
       .transform(utf8.decoder)
       .transform(const LineSplitter())
       .listen((String line) {
         print('stdout: $line');
       }, onDone: () { stdoutDone.complete(); });
   process.stderr
       .transform(utf8.decoder)
       .transform(const LineSplitter())
       .listen((String line) {
         print('stderr: $line');
       }, onDone: () { stderrDone.complete(); });

   await Future.wait<Null>(<Future<Null>>[stdoutDone.future, stderrDone.future]);
   final int exitCode = await process.exitCode;

   if (exitCode != 0 && !canFail)
     fail('Executable failed with exit code $exitCode.');

   return exitCode;
 }

 /// Executes a command and returns its standard output as a String.
 ///
 /// For logging purposes, the command's output is also printed out.
 Future<String> eval(
   String executable,
   List<String> arguments, {
   Map<String, String> environment,
   bool canFail = false,
 }) async {
   final Process process = await startProcess(executable, arguments, environment: environment);

   final StringBuffer output = new StringBuffer();
   final Completer<Null> stdoutDone = new Completer<Null>();
   final Completer<Null> stderrDone = new Completer<Null>();
   process.stdout
       .transform(utf8.decoder)
       .transform(const LineSplitter())
       .listen((String line) {
         print('stdout: $line');
         output.writeln(line);
       }, onDone: () { stdoutDone.complete(); });
   process.stderr
       .transform(utf8.decoder)
       .transform(const LineSplitter())
       .listen((String line) {
         print('stderr: $line');
       }, onDone: () { stderrDone.complete(); });

   await Future.wait<Null>(<Future<Null>>[stdoutDone.future, stderrDone.future]);
   final int exitCode = await process.exitCode;

   if (exitCode != 0 && !canFail)
     fail('Executable failed with exit code $exitCode.');

   return output.toString().trimRight();
 }

 Future<int> flutter(String command, {
   List<String> options = const <String>[],
   bool canFail = false,
   Map<String, String> environment,
 }) {
   final List<String> args = <String>[command]..addAll(options);
   return exec(path.join(flutterDirectory.path, 'bin', 'flutter'), args,
       canFail: canFail, environment: environment);
 }

 /// Runs a `flutter` command and returns the standard output as a string.
 Future<String> evalFlutter(String command, {
   List<String> options = const <String>[],
   bool canFail = false,
   Map<String, String> environment,
 }) {
   final List<String> args = <String>[command]..addAll(options);
   return eval(path.join(flutterDirectory.path, 'bin', 'flutter'), args,
       canFail: canFail, environment: environment);
 }

 String get dartBin =>
     path.join(flutterDirectory.path, 'bin', 'cache', 'dart-sdk', 'bin', 'dart');

 Future<int> dart(List<String> args) => exec(dartBin, args);

 Future<dynamic> inDirectory(dynamic directory, Future<dynamic> action()) async {
   final String previousCwd = cwd;
   try {
     cd(directory);
     return await action();
   } finally {
     cd(previousCwd);
   }
 }

 void cd(dynamic directory) {
   Directory d;
   if (directory is String) {
     cwd = directory;
     d = dir(directory);
   } else if (directory is Directory) {
     cwd = directory.path;
     d = directory;
   } else {
     throw 'Unsupported type ${directory.runtimeType} of $directory';
   }

   if (!d.existsSync())
     throw 'Cannot cd into directory that does not exist: $directory';
 }

 Directory get flutterDirectory => dir('../..').absolute;

 String requireEnvVar(String name) {
   final String value = Platform.environment[name];

   if (value == null)
     fail('$name environment variable is missing. Quitting.');

   return value;
 }

 T requireConfigProperty<T>(Map<String, dynamic> map, String propertyName) {
   if (!map.containsKey(propertyName))
     fail('Configuration property not found: $propertyName');
   final T result = map[propertyName];
   return result;
 }

 String jsonEncode(dynamic data) {
   return const JsonEncoder.withIndent('  ').convert(data) + '\n';
 }

 Future<Null> getFlutter(String revision) async {
   section('Get Flutter!');

   if (exists(flutterDirectory)) {
     rmTree(flutterDirectory);
   }

   await inDirectory(flutterDirectory.parent, () async {
     await exec('git', <String>['clone', 'https://github.com/flutter/flutter.git']);
   });

   await inDirectory(flutterDirectory, () async {
     await exec('git', <String>['checkout', revision]);
   });

   await flutter('config', options: <String>['--no-analytics']);

   section('flutter doctor');
   await flutter('doctor');

   section('flutter update-packages');
   await flutter('update-packages');
 }

 void checkNotNull(Object o1,
     [Object o2 = 1,
     Object o3 = 1,
     Object o4 = 1,
     Object o5 = 1,
     Object o6 = 1,
     Object o7 = 1,
     Object o8 = 1,
     Object o9 = 1,
     Object o10 = 1]) {
   if (o1 == null)
     throw 'o1 is null';
   if (o2 == null)
     throw 'o2 is null';
   if (o3 == null)
     throw 'o3 is null';
   if (o4 == null)
     throw 'o4 is null';
   if (o5 == null)
     throw 'o5 is null';
   if (o6 == null)
     throw 'o6 is null';
   if (o7 == null)
     throw 'o7 is null';
   if (o8 == null)
     throw 'o8 is null';
   if (o9 == null)
     throw 'o9 is null';
   if (o10 == null)
     throw 'o10 is null';
 }

 /// Splits [from] into lines and selects those that contain [pattern].
 Iterable<String> grep(Pattern pattern, {@required String from}) {
   return from.split('\n').where((String line) {
     return line.contains(pattern);
   });
 }

 /// Captures asynchronous stack traces thrown by [callback].
 ///
 /// This is a convenience wrapper around [Chain] optimized for use with
 /// `async`/`await`.
 ///
 /// Example:
 ///
 ///     try {
 ///       await captureAsyncStacks(() { /* async things */ });
 ///     } catch (error, chain) {
 ///
 ///     }
 Future<Null> runAndCaptureAsyncStacks(Future<Null> callback()) {
   final Completer<Null> completer = new Completer<Null>();
   Chain.capture(() async {
     await callback();
     completer.complete();
   }, onError: completer.completeError);
   return completer.future;
 }

 /// Return an unused TCP port number.
 Future<int> findAvailablePort() async {
   int port = 20000;
   while (true) {
     try {
       final ServerSocket socket =
           await ServerSocket.bind(InternetAddress.LOOPBACK_IP_V4, port); // ignore: deprecated_member_use
       await socket.close();
       return port;
     } catch (_) {
       port++;
     }
   }
 }

 bool canRun(String path) => _processManager.canRun(path);

 String extractCloudAuthTokenArg(List<String> rawArgs) {
   final ArgParser argParser = new ArgParser()..addOption('cloud-auth-token');
   ArgResults args;
   try {
     args = argParser.parse(rawArgs);
   } on FormatException catch (error) {
     stderr.writeln('${error.message}\n');
     stderr.writeln('Usage:\n');
     stderr.writeln(argParser.usage);
     return null;
   }

   final String token = args['cloud-auth-token'];
   if (token == null) {
     stderr.writeln('Required option --cloud-auth-token not found');
     return null;
   }
   return token;
 }

 // "An Observatory debugger and profiler on ... is available at: http://127.0.0.1:8100/"
 final RegExp _kObservatoryRegExp = new RegExp(r'An Observatory debugger .* is available at: (\S+:(\d+))');

 bool lineContainsServicePort(String line) => line.contains(_kObservatoryRegExp);

 int parseServicePort(String line) {
   final Match match = _kObservatoryRegExp.firstMatch(line);
   return match == null ? null : int.parse(match.group(2));
 }

 /// If FLUTTER_ENGINE environment variable is set then we need to pass
 /// correct --local-engine setting too.
 void setLocalEngineOptionIfNecessary(List<String> options, [String flavor]) {
   if (Platform.environment['FLUTTER_ENGINE'] != null) {
     if (flavor == null) {
       // If engine flavor was not specified explicitly then scan options looking
       // for flags that specify the engine flavor (--release, --profile or
       // --debug). Default flavor to debug if no flags were found.
       const Map<String, String> optionToFlavor = const <String, String>{
         '--release': 'release',
         '--debug': 'debug',
         '--profile': 'profile',
       };

       for (String option in options) {
         flavor = optionToFlavor[option];
         if (flavor != null) {
           break;
         }
       }

       flavor ??= 'debug';
     }

     const Map<DeviceOperatingSystem, String> osNames = const <DeviceOperatingSystem, String>{
       DeviceOperatingSystem.ios: 'ios',
       DeviceOperatingSystem.android: 'android',
     };

     options.add('--local-engine=${osNames[deviceOperatingSystem]}_$flavor');
   }
 }
	// Copyright (c) 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.

	import 'dart:async';
	import 'dart:convert';
	import 'dart:io';
	import 'dart:math' as math;

	import 'package:args/args.dart';
	import 'package:meta/meta.dart';
	import 'package:path/path.dart' as path;
	import 'package:process/process.dart';
	import 'package:stack_trace/stack_trace.dart';

	import 'adb.dart';

	/// Virtual current working directory, which affect functions, such as [exec].
	String cwd = Directory.current.path;

	List<ProcessInfo> _runningProcesses = <ProcessInfo>[];
	ProcessManager _processManager = const LocalProcessManager();

	class ProcessInfo {
	ProcessInfo(this.command, this.process);

	final DateTime startTime = new DateTime.now();
	final String command;
	final Process process;

	@override
	String toString() {
	return '''
	command : $command
	started : $startTime
	pid : ${process.pid}
	'''
	.trim();
	}
	}

	/// Result of a health check for a specific parameter.
	class HealthCheckResult {
	HealthCheckResult.success([this.details]) : succeeded = true;
	HealthCheckResult.failure(this.details) : succeeded = false;
	HealthCheckResult.error(dynamic error, dynamic stackTrace)
	: succeeded = false,
	details = 'ERROR: $error${'\n$stackTrace' ?? ''}';

	final bool succeeded;
	final String details;

	@override
	String toString() {
	final StringBuffer buf = new StringBuffer(succeeded ? 'succeeded' : 'failed');
	if (details != null && details.trim().isNotEmpty) {
	buf.writeln();
	// Indent details by 4 spaces
	for (String line in details.trim().split('\n')) {
	buf.writeln(' $line');
	}
	}
	return '$buf';
	}
	}

	class BuildFailedError extends Error {
	BuildFailedError(this.message);

	final String message;

	@override
	String toString() => message;
	}

	void fail(String message) {
	throw new BuildFailedError(message);
	}

	void rm(FileSystemEntity entity) {
	if (entity.existsSync())
	entity.deleteSync();
	}

	/// Remove recursively.
	void rmTree(FileSystemEntity entity) {
	if (entity.existsSync())
	entity.deleteSync(recursive: true);
	}

	List<FileSystemEntity> ls(Directory directory) => directory.listSync();

	Directory dir(String path) => new Directory(path);

	File file(String path) => new File(path);

	void copy(File sourceFile, Directory targetDirectory, {String name}) {
	final File target = file(
	path.join(targetDirectory.path, name ?? path.basename(sourceFile.path)));
	target.writeAsBytesSync(sourceFile.readAsBytesSync());
	}

	void recursiveCopy(Directory source, Directory target) {
	if (!target.existsSync())
	target.createSync();

	for (FileSystemEntity entity in source.listSync(followLinks: false)) {
	final String name = path.basename(entity.path);
	if (entity is Directory)
	recursiveCopy(entity, new Directory(path.join(target.path, name)));
	else if (entity is File) {
	final File dest = new File(path.join(target.path, name));
	dest.writeAsBytesSync(entity.readAsBytesSync());
	}
	}
	}

	FileSystemEntity move(FileSystemEntity whatToMove,
	{Directory to, String name}) {
	return whatToMove
	.renameSync(path.join(to.path, name ?? path.basename(whatToMove.path)));
	}

	/// Equivalent of `mkdir directory`.
	void mkdir(Directory directory) {
	directory.createSync();
	}

	/// Equivalent of `mkdir -p directory`.
	void mkdirs(Directory directory) {
	directory.createSync(recursive: true);
	}

	bool exists(FileSystemEntity entity) => entity.existsSync();

	void section(String title) {
	title = '╡ ••• $title ••• ╞';
	final String line = '═' * math.max((80 - title.length) ~/ 2, 2);
	String output = '$line$title$line';
	if (output.length == 79)
	output += '═';
	print('\n\n$output\n');
	}

	Future<String> getDartVersion() async {
	// The Dart VM returns the version text to stderr.
	final ProcessResult result = _processManager.runSync(<String>[dartBin, '--version']);
	String version = result.stderr.trim();

	// Convert:
	// Dart VM version: 1.17.0-dev.2.0 (Tue May 3 12:14:52 2016) on "macos_x64"
	// to:
	// 1.17.0-dev.2.0
	if (version.contains('('))
	version = version.substring(0, version.indexOf('(')).trim();
	if (version.contains(':'))
	version = version.substring(version.indexOf(':') + 1).trim();

	return version.replaceAll('"', "'");
	}

	Future<String> getCurrentFlutterRepoCommit() {
	if (!dir('${flutterDirectory.path}/.git').existsSync()) {
	return null;
	}

	return inDirectory(flutterDirectory, () {
	return eval('git', <String>['rev-parse', 'HEAD']);
	});
	}

	Future<DateTime> getFlutterRepoCommitTimestamp(String commit) {
	// git show -s --format=%at 4b546df7f0b3858aaaa56c4079e5be1ba91fbb65
	return inDirectory(flutterDirectory, () async {
	final String unixTimestamp = await eval('git', <String>[
	'show',
	'-s',
	'--format=%at',
	commit,
	]);
	final int secondsSinceEpoch = int.parse(unixTimestamp);
	return new DateTime.fromMillisecondsSinceEpoch(secondsSinceEpoch * 1000);
	});
	}

	/// Starts a subprocess.
	///
	/// The first argument is the full path to the executable to run.
	///
	/// The second argument is the list of arguments to provide on the command line.
	/// This argument can be null, indicating no arguments (same as the empty list).
	///
	/// The `environment` argument can be provided to configure environment variables
	/// that will be made available to the subprocess. The `BOT` environment variable
	/// is always set and overrides any value provided in the `environment` argument.
	/// The `isBot` argument controls the value of the `BOT` variable. It will either
	/// be "true", if `isBot` is true (the default), or "false" if it is false.
	///
	/// The `BOT` variable is in particular used by the `flutter` tool to determine
	/// how verbose to be and whether to enable analytics by default.
	///
	/// The working directory can be provided using the `workingDirectory` argument.
	/// By default it will default to the current working directory (see [cwd]).
	///
	/// Information regarding the execution of the subprocess is printed to the
	/// console.
	///
	/// The actual process executes asynchronously. A handle to the subprocess is
	/// returned in the form of a [Future] that completes to a [Process] object.
	Future<Process> startProcess(
	String executable,
	List<String> arguments, {
	Map<String, String> environment,
	bool isBot = true, // set to false to pretend not to be on a bot (e.g. to test user-facing outputs)
	String workingDirectory,
	}) async {
	assert(isBot != null);
	final String command = '$executable ${arguments?.join(" ") ?? ""}';
	print('\nExecuting: $command');
	environment ??= <String, String>{};
	environment['BOT'] = isBot ? 'true' : 'false';
	final Process process = await _processManager.start(
	<String>[executable]..addAll(arguments),
	environment: environment,
	workingDirectory: workingDirectory ?? cwd,
	);
	final ProcessInfo processInfo = new ProcessInfo(command, process);
	_runningProcesses.add(processInfo);

	process.exitCode.then((int exitCode) {
	print('exitcode: $exitCode');
	_runningProcesses.remove(processInfo);
	});

	return process;
	}

	Future<Null> forceQuitRunningProcesses() async {
	if (_runningProcesses.isEmpty)
	return;

	// Give normally quitting processes a chance to report their exit code.
	await new Future<Null>.delayed(const Duration(seconds: 1));

	// Whatever's left, kill it.
	for (ProcessInfo p in _runningProcesses) {
	print('Force quitting process:\n$p');
	if (!p.process.kill()) {
	print('Failed to force quit process');
	}
	}
	_runningProcesses.clear();
	}

	/// Executes a command and returns its exit code.
	Future<int> exec(
	String executable,
	List<String> arguments, {
	Map<String, String> environment,
	bool canFail = false,
	}) async {
	final Process process = await startProcess(executable, arguments, environment: environment);

	final Completer<Null> stdoutDone = new Completer<Null>();
	final Completer<Null> stderrDone = new Completer<Null>();
	process.stdout
	.transform(utf8.decoder)
	.transform(const LineSplitter())
	.listen((String line) {
	print('stdout: $line');
	}, onDone: () { stdoutDone.complete(); });
	process.stderr
	.transform(utf8.decoder)
	.transform(const LineSplitter())
	.listen((String line) {
	print('stderr: $line');
	}, onDone: () { stderrDone.complete(); });

	await Future.wait<Null>(<Future<Null>>[stdoutDone.future, stderrDone.future]);
	final int exitCode = await process.exitCode;

	if (exitCode != 0 && !canFail)
	fail('Executable failed with exit code $exitCode.');

	return exitCode;
	}

	/// Executes a command and returns its standard output as a String.
	///
	/// For logging purposes, the command's output is also printed out.
	Future<String> eval(
	String executable,
	List<String> arguments, {
	Map<String, String> environment,
	bool canFail = false,
	}) async {
	final Process process = await startProcess(executable, arguments, environment: environment);

	final StringBuffer output = new StringBuffer();
	final Completer<Null> stdoutDone = new Completer<Null>();
	final Completer<Null> stderrDone = new Completer<Null>();
	process.stdout
	.transform(utf8.decoder)
	.transform(const LineSplitter())
	.listen((String line) {
	print('stdout: $line');
	output.writeln(line);
	}, onDone: () { stdoutDone.complete(); });
	process.stderr
	.transform(utf8.decoder)
	.transform(const LineSplitter())
	.listen((String line) {
	print('stderr: $line');
	}, onDone: () { stderrDone.complete(); });

	await Future.wait<Null>(<Future<Null>>[stdoutDone.future, stderrDone.future]);
	final int exitCode = await process.exitCode;

	if (exitCode != 0 && !canFail)
	fail('Executable failed with exit code $exitCode.');

	return output.toString().trimRight();
	}

	Future<int> flutter(String command, {
	List<String> options = const <String>[],
	bool canFail = false,
	Map<String, String> environment,
	}) {
	final List<String> args = <String>[command]..addAll(options);
	return exec(path.join(flutterDirectory.path, 'bin', 'flutter'), args,
	canFail: canFail, environment: environment);
	}

	/// Runs a `flutter` command and returns the standard output as a string.
	Future<String> evalFlutter(String command, {
	List<String> options = const <String>[],
	bool canFail = false,
	Map<String, String> environment,
	}) {
	final List<String> args = <String>[command]..addAll(options);
	return eval(path.join(flutterDirectory.path, 'bin', 'flutter'), args,
	canFail: canFail, environment: environment);
	}

	String get dartBin =>
	path.join(flutterDirectory.path, 'bin', 'cache', 'dart-sdk', 'bin', 'dart');

	Future<int> dart(List<String> args) => exec(dartBin, args);

	Future<dynamic> inDirectory(dynamic directory, Future<dynamic> action()) async {
	final String previousCwd = cwd;
	try {
	cd(directory);
	return await action();
	} finally {
	cd(previousCwd);
	}
	}

	void cd(dynamic directory) {
	Directory d;
	if (directory is String) {
	cwd = directory;
	d = dir(directory);
	} else if (directory is Directory) {
	cwd = directory.path;
	d = directory;
	} else {
	throw 'Unsupported type ${directory.runtimeType} of $directory';
	}

	if (!d.existsSync())
	throw 'Cannot cd into directory that does not exist: $directory';
	}

	Directory get flutterDirectory => dir('../..').absolute;

	String requireEnvVar(String name) {
	final String value = Platform.environment[name];

	if (value == null)
	fail('$name environment variable is missing. Quitting.');

	return value;
	}

	T requireConfigProperty<T>(Map<String, dynamic> map, String propertyName) {
	if (!map.containsKey(propertyName))
	fail('Configuration property not found: $propertyName');
	final T result = map[propertyName];
	return result;
	}

	String jsonEncode(dynamic data) {
	return const JsonEncoder.withIndent(' ').convert(data) + '\n';
	}

	Future<Null> getFlutter(String revision) async {
	section('Get Flutter!');

	if (exists(flutterDirectory)) {
	rmTree(flutterDirectory);
	}

	await inDirectory(flutterDirectory.parent, () async {
	await exec('git', <String>['clone', 'https://github.com/flutter/flutter.git']);
	});

	await inDirectory(flutterDirectory, () async {
	await exec('git', <String>['checkout', revision]);
	});

	await flutter('config', options: <String>['--no-analytics']);

	section('flutter doctor');
	await flutter('doctor');

	section('flutter update-packages');
	await flutter('update-packages');
	}

	void checkNotNull(Object o1,
	[Object o2 = 1,
	Object o3 = 1,
	Object o4 = 1,
	Object o5 = 1,
	Object o6 = 1,
	Object o7 = 1,
	Object o8 = 1,
	Object o9 = 1,
	Object o10 = 1]) {
	if (o1 == null)
	throw 'o1 is null';
	if (o2 == null)
	throw 'o2 is null';
	if (o3 == null)
	throw 'o3 is null';
	if (o4 == null)
	throw 'o4 is null';
	if (o5 == null)
	throw 'o5 is null';
	if (o6 == null)
	throw 'o6 is null';
	if (o7 == null)
	throw 'o7 is null';
	if (o8 == null)
	throw 'o8 is null';
	if (o9 == null)
	throw 'o9 is null';
	if (o10 == null)
	throw 'o10 is null';
	}

	/// Splits [from] into lines and selects those that contain [pattern].
	Iterable<String> grep(Pattern pattern, {@required String from}) {
	return from.split('\n').where((String line) {
	return line.contains(pattern);
	});
	}

	/// Captures asynchronous stack traces thrown by [callback].
	///
	/// This is a convenience wrapper around [Chain] optimized for use with
	/// `async`/`await`.
	///
	/// Example:
	///
	/// try {
	/// await captureAsyncStacks(() { /* async things */ });
	/// } catch (error, chain) {
	///
	/// }
	Future<Null> runAndCaptureAsyncStacks(Future<Null> callback()) {
	final Completer<Null> completer = new Completer<Null>();
	Chain.capture(() async {
	await callback();
	completer.complete();
	}, onError: completer.completeError);
	return completer.future;
	}

	/// Return an unused TCP port number.
	Future<int> findAvailablePort() async {
	int port = 20000;
	while (true) {
	try {
	final ServerSocket socket =
	await ServerSocket.bind(InternetAddress.LOOPBACK_IP_V4, port); // ignore: deprecated_member_use
	await socket.close();
	return port;
	} catch (_) {
	port++;
	}
	}
	}

	bool canRun(String path) => _processManager.canRun(path);

	String extractCloudAuthTokenArg(List<String> rawArgs) {
	final ArgParser argParser = new ArgParser()..addOption('cloud-auth-token');
	ArgResults args;
	try {
	args = argParser.parse(rawArgs);
	} on FormatException catch (error) {
	stderr.writeln('${error.message}\n');
	stderr.writeln('Usage:\n');
	stderr.writeln(argParser.usage);
	return null;
	}

	final String token = args['cloud-auth-token'];
	if (token == null) {
	stderr.writeln('Required option --cloud-auth-token not found');
	return null;
	}
	return token;
	}

	// "An Observatory debugger and profiler on ... is available at: http://127.0.0.1:8100/"
	final RegExp _kObservatoryRegExp = new RegExp(r'An Observatory debugger .* is available at: (\S+:(\d+))');

	bool lineContainsServicePort(String line) => line.contains(_kObservatoryRegExp);

	int parseServicePort(String line) {
	final Match match = _kObservatoryRegExp.firstMatch(line);
	return match == null ? null : int.parse(match.group(2));
	}

	/// If FLUTTER_ENGINE environment variable is set then we need to pass
	/// correct --local-engine setting too.
	void setLocalEngineOptionIfNecessary(List<String> options, [String flavor]) {
	if (Platform.environment['FLUTTER_ENGINE'] != null) {
	if (flavor == null) {
	// If engine flavor was not specified explicitly then scan options looking
	// for flags that specify the engine flavor (--release, --profile or
	// --debug). Default flavor to debug if no flags were found.
	const Map<String, String> optionToFlavor = const <String, String>{
	'--release': 'release',
	'--debug': 'debug',
	'--profile': 'profile',
	};

	for (String option in options) {
	flavor = optionToFlavor[option];
	if (flavor != null) {
	break;
	}
	}

	flavor ??= 'debug';
	}

	const Map<DeviceOperatingSystem, String> osNames = const <DeviceOperatingSystem, String>{
	DeviceOperatingSystem.ios: 'ios',
	DeviceOperatingSystem.android: 'android',
	};

	options.add('--local-engine=${osNames[deviceOperatingSystem]}_$flavor');
	}
	}