return exit codes on failures

packages/flutter_tools/bin/sky_server.dart

@@ -5,10 +5,10 @@
 import 'dart:io';
 
 import 'package:args/args.dart';
-import 'package:shelf_static/shelf_static.dart';
-import 'package:shelf/shelf_io.dart' as io;
 import 'package:shelf/shelf.dart';
+import 'package:shelf/shelf_io.dart' as io;
 import 'package:shelf_route/shelf_route.dart' as shelf_route;
+import 'package:shelf_static/shelf_static.dart';
 
 void printUsage(parser) {
   print('Usage: sky_server [-v] PORT');

packages/flutter_tools/bin/sky_test.dart

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:test/src/executable.dart' as executable;
 import 'package:sky_tools/src/test/loader.dart' as loader;
+import 'package:test/src/executable.dart' as executable;
 
 main(List<String> args) {
   loader.installHook();

packages/flutter_tools/lib/executable.dart

@@ -8,9 +8,9 @@ import 'dart:io';
 import 'package:args/command_runner.dart';
 import 'package:logging/logging.dart';
 
-import 'src/commands/flutter_command_runner.dart';
 import 'src/commands/build.dart';
 import 'src/commands/cache.dart';
+import 'src/commands/flutter_command_runner.dart';
 import 'src/commands/init.dart';
 import 'src/commands/install.dart';
 import 'src/commands/list.dart';
@@ -25,13 +25,18 @@ import 'src/commands/trace.dart';
 ///
 /// This function is intended to be used from the [flutter] command line tool.
 Future main(List<String> args) async {
-  Logger.root.level = Level.WARNING;
+  // This level can be adjusted by users through the `--verbose` option.
+  Logger.root.level = Level.SEVERE;
   Logger.root.onRecord.listen((LogRecord record) {
-    print('${record.level.name}: ${record.message}');
+    if (record.level >= Level.WARNING) {
+      stderr.writeln(record.message);
+    } else {
+      print(record.message);
+    }
     if (record.error != null)
-      print(record.error);
+      stderr.writeln(record.error);
     if (record.stackTrace != null)
-      print(record.stackTrace);
+      stderr.writeln(record.stackTrace);
   });
 
   FlutterCommandRunner runner = new FlutterCommandRunner()
@@ -48,9 +53,11 @@ Future main(List<String> args) async {
     ..addCommand(new TraceCommand());
 
   try {
-    await runner.run(args);
+    dynamic result = await runner.run(args);
+    if (result is int)
+      exit(result);
   } on UsageException catch (e) {
-    print(e);
-    exit(1);
+    stderr.writeln(e);
+    exit(4);
   }
 }

packages/flutter_tools/lib/src/commands/build.dart

@@ -81,24 +81,24 @@ Iterable<_MaterialAsset> _parseMaterialAssets(Map manifestDescriptor) sync* {
   }
 }
 
-Future _loadManifest(String manifestPath) async {
+dynamic _loadManifest(String manifestPath) {
   if (manifestPath == null)
     return null;
-  String manifestDescriptor = await new File(manifestPath).readAsString();
+  String manifestDescriptor = new File(manifestPath).readAsStringSync();
   return loadYaml(manifestDescriptor);
 }
 
-Future<ArchiveFile> _createFile(String key, String assetBase) async {
+ArchiveFile _createFile(String key, String assetBase) {
   File file = new File('${assetBase}/${key}');
-  if (!await file.exists())
+  if (!file.existsSync())
     return null;
-  List<int> content = await file.readAsBytes();
+  List<int> content = file.readAsBytesSync();
   return new ArchiveFile.noCompress(key, content.length, content);
 }
 
-Future<ArchiveFile> _createSnapshotFile(String snapshotPath) async {
+ArchiveFile _createSnapshotFile(String snapshotPath) {
   File file = new File(snapshotPath);
-  List<int> content = await file.readAsBytes();
+  List<int> content = file.readAsBytesSync();
   return new ArchiveFile(_kSnapshotKey, content.length, content);
 }
 
@@ -145,7 +145,7 @@ class BuildCommand extends FlutterCommand {
     String outputPath: _kDefaultOutputPath,
     String snapshotPath: _kDefaultSnapshotPath
   }) async {
-    Map manifestDescriptor = await _loadManifest(manifestPath);
+    Map manifestDescriptor = _loadManifest(manifestPath);
 
     Iterable<_Asset> assets = _parseAssets(manifestDescriptor, manifestPath);
     Iterable<_MaterialAsset> materialAssets = _parseMaterialAssets(manifestDescriptor);
@@ -156,20 +156,21 @@ class BuildCommand extends FlutterCommand {
     if (result != 0)
       return result;
 
-    archive.addFile(await _createSnapshotFile(snapshotPath));
+    archive.addFile(_createSnapshotFile(snapshotPath));
 
     for (_Asset asset in assets)
-      archive.addFile(await _createFile(asset.key, asset.base));
+      archive.addFile(_createFile(asset.key, asset.base));
 
     for (_MaterialAsset asset in materialAssets) {
-      ArchiveFile file = await _createFile(asset.key, assetBase);
+      ArchiveFile file = _createFile(asset.key, assetBase);
       if (file != null)
         archive.addFile(file);
     }
 
     File outputFile = new File(outputPath);
-    await outputFile.writeAsString('#!mojo mojo:sky_viewer\n');
-    await outputFile.writeAsBytes(new ZipEncoder().encode(archive), mode: FileMode.APPEND, flush: true);
+    outputFile.writeAsStringSync('#!mojo mojo:sky_viewer\n');
+    outputFile.writeAsBytesSync(
+        new ZipEncoder().encode(archive), mode: FileMode.APPEND, flush: true);
     return 0;
   }
 }

packages/flutter_tools/lib/src/commands/flutter_command_runner.dart

@@ -94,7 +94,7 @@ class FlutterCommandRunner extends CommandRunner {
 
   ArgResults _globalResults;
 
-  Future<int> runCommand(ArgResults globalResults) async {
+  Future<int> runCommand(ArgResults globalResults) {
     if (globalResults['verbose'])
       Logger.root.level = Level.INFO;
 

packages/flutter_tools/lib/src/commands/list.dart

@@ -6,8 +6,8 @@ import 'dart:async';
 
 import 'package:logging/logging.dart';
 
-import 'flutter_command.dart';
 import '../device.dart';
+import 'flutter_command.dart';
 
 final Logger _logging = new Logger('sky_tools.list');
 

packages/flutter_tools/lib/src/commands/logs.dart

@@ -6,8 +6,8 @@ import 'dart:async';
 
 import 'package:logging/logging.dart';
 
-import 'flutter_command.dart';
 import '../device.dart';
+import 'flutter_command.dart';
 
 final Logger _logging = new Logger('sky_tools.logs');
 

packages/flutter_tools/lib/src/commands/run_mojo.dart

@@ -31,17 +31,17 @@ class RunMojoCommand extends Command {
   }
 
   // TODO(abarth): Why not use path.absolute?
-  Future<String> _makePathAbsolute(String relativePath) async {
+  String _makePathAbsolute(String relativePath) {
     File file = new File(relativePath);
-    if (!await file.exists()) {
+    if (!file.existsSync()) {
       throw new Exception("Path \"${relativePath}\" does not exist");
     }
     return file.absolute.path;
   }
 
-  Future<int> _runAndroid(String mojoPath, _MojoConfig mojoConfig, String appPath, List<String> additionalArgs) async {
+  Future<int> _runAndroid(String mojoPath, _MojoConfig mojoConfig, String appPath, List<String> additionalArgs) {
     String skyViewerUrl = ArtifactStore.googleStorageUrl('viewer', 'android-arm');
-    String command = await _makePathAbsolute(path.join(mojoPath, 'mojo', 'devtools', 'common', 'mojo_run'));
+    String command = _makePathAbsolute(path.join(mojoPath, 'mojo', 'devtools', 'common', 'mojo_run'));
     String appName = path.basename(appPath);
     String appDir = path.dirname(appPath);
     String buildFlag = mojoConfig == _MojoConfig.Debug ? '--debug' : '--release';
@@ -65,9 +65,9 @@ class RunMojoCommand extends Command {
   }
 
   Future<int> _runLinux(String mojoPath, _MojoConfig mojoConfig, String appPath, List<String> additionalArgs) async {
-    String viewerPath = await _makePathAbsolute(await ArtifactStore.getPath(Artifact.skyViewerMojo));
+    String viewerPath = _makePathAbsolute(await ArtifactStore.getPath(Artifact.skyViewerMojo));
     String mojoBuildType = mojoConfig == _MojoConfig.Debug ? 'Debug' : 'Release';
-    String mojoShellPath = await _makePathAbsolute(path.join(mojoPath, 'out', mojoBuildType, 'mojo_shell'));
+    String mojoShellPath = _makePathAbsolute(path.join(mojoPath, 'out', mojoBuildType, 'mojo_shell'));
     List<String> cmd = [
       mojoShellPath,
       'file://${appPath}',
@@ -93,7 +93,7 @@ class RunMojoCommand extends Command {
     }
     String mojoPath = argResults['mojo-path'];
     _MojoConfig mojoConfig = argResults['mojo-debug'] ? _MojoConfig.Debug : _MojoConfig.Release;
-    String appPath = await _makePathAbsolute(argResults['app']);
+    String appPath = _makePathAbsolute(argResults['app']);
 
     args.addAll(argResults.rest);
     if (argResults['android']) {

packages/flutter_tools/lib/src/commands/start.dart

@@ -67,6 +67,14 @@ class StartCommand extends FlutterCommand {
       }
     }
 
+    if (!startedSomething) {
+      if (!devices.all.any((device) => device.isConnected())) {
+        _logging.severe('Unable to run application - no connected devices.');
+      } else {
+        _logging.severe('Unable to run application.');
+      }
+    }
+
     return startedSomething ? 0 : 2;
   }
 }

packages/flutter_tools/lib/src/commands/trace.dart

@@ -6,9 +6,9 @@ import 'dart:async';
 
 import 'package:logging/logging.dart';
 
-import 'flutter_command.dart';
 import '../application_package.dart';
 import '../device.dart';
+import 'flutter_command.dart';
 
 final Logger _logging = new Logger('sky_tools.trace');
 

packages/flutter_tools/lib/src/device.dart

@@ -277,7 +277,7 @@ class IOSDevice extends Device {
       return 2;
     }
     return runCommandAndStreamOutput([loggerPath],
-        prefix: 'IOS DEV: ', filter: new RegExp(r'.*SkyShell.*'));
+        prefix: 'iOS dev: ', filter: new RegExp(r'.*SkyShell.*'));
   }
 }
 
@@ -499,7 +499,7 @@ class IOSSimulator extends Device {
       runSync(['rm', logFilePath]);
     }
     return runCommandAndStreamOutput(['tail', '-f', logFilePath],
-        prefix: 'IOS SIM: ', filter: new RegExp(r'.*SkyShell.*'));
+        prefix: 'iOS sim: ', filter: new RegExp(r'.*SkyShell.*'));
   }
 }
 
@@ -575,7 +575,7 @@ class AndroidDevice extends Device {
     _hasValidAndroid = _checkForLollipopOrLater();
 
     if (!_hasAdb || !_hasValidAndroid) {
-      _logging.severe('Unable to run on Android.');
+      _logging.warning('Unable to run on Android.');
     }
   }
 
@@ -855,7 +855,7 @@ class AndroidDevice extends Device {
       '-s',
       'sky',
       'chromium',
-    ], prefix: 'ANDROID: ');
+    ], prefix: 'android: ');
   }
 
   void startTracing(AndroidApk apk) {

packages/flutter_tools/test/stop_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-library stop_test;
-
 import 'package:args/command_runner.dart';
 import 'package:mockito/mockito.dart';
 import 'package:sky_tools/src/commands/stop.dart';

packages/flutter_tools/test/trace_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-library trace_test;
-
 import 'package:args/command_runner.dart';
 import 'package:mockito/mockito.dart';
 import 'package:sky_tools/src/commands/trace.dart';