Refactor flutter command exit code - part 2 (#6817)

* convert pubGet to throw ToolExit on non-zero exit code
* convert commandValidator to throw ToolExit for non-zero exit code
* convert flutter commands to throw ToolExit for non-zero exit code
* use convenience method throwToolExit
* only show "if this problem persists" for unusual exceptions

packages/flutter_tools/bin/fuchsia_builder.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 
 import 'package:args/args.dart';
 
+import '../lib/src/base/common.dart';
 import '../lib/src/base/context.dart';
 import '../lib/src/base/logger.dart';
 import '../lib/src/cache.dart';
@@ -42,7 +43,8 @@ Future<Null> main(List<String> args) async {
   }
   Cache.flutterRoot = Platform.environment['FLUTTER_ROOT'];
   String outputPath = argResults[_kOptionOutput];
-  final int buildResult = await assemble(
+  try {
+    await assemble(
       outputPath: outputPath,
       snapshotFile: new File(argResults[_kOptionSnapshot]),
       workingDirPath: argResults[_kOptionWorking],
@@ -50,9 +52,9 @@ Future<Null> main(List<String> args) async {
       manifestPath: defaultManifestPath,
       includeDefaultFonts: false,
     );
-  if (buildResult != 0) {
-    printError('Error building $outputPath: $buildResult.');
-    exit(buildResult);
+  } on ToolExit catch (e) {
+    printError(e.message);
+    exit(e.exitCode);
   }
   final int headerResult = _addHeader(outputPath, argResults[_kOptionHeader]);
   if (headerResult != 0) {

packages/flutter_tools/lib/executable.dart

@@ -114,9 +114,11 @@ Future<Null> main(List<String> args) async {
         stderr.writeln(chain.terse.toString());
         stderr.writeln();
       }
+      if (error.isUnusual) {
         stderr.writeln('If this problem persists, please report the problem at');
         stderr.writeln('https://github.com/flutter/flutter/issues/new');
-      _exit(error.exitCode ?? 65);
+      }
+      _exit(error.exitCode ?? 1);
     } else if (error is ProcessExit) {
       // We've caught an exit code.
       _exit(error.exitCode);

packages/flutter_tools/lib/src/android/gradle.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 
 import 'package:path/path.dart' as path;
 
+import '../base/common.dart';
 import '../base/logger.dart';
 import '../base/os.dart';
 import '../base/process.dart';
@@ -90,7 +91,7 @@ String locateProjectGradlew({ bool ensureExecutable: true }) {
   }
 }
 
-Future<int> buildGradleProject(BuildMode buildMode) async {
+Future<Null> buildGradleProject(BuildMode buildMode) async {
   // Create android/local.properties.
   File localProperties = new File('android/local.properties');
   if (!localProperties.existsSync()) {
@@ -111,10 +112,9 @@ Future<int> buildGradleProject(BuildMode buildMode) async {
   if (gradlew == null) {
     String gradle = locateSystemGradle();
     if (gradle == null) {
-      printError(
+      throwToolExit(
         'Unable to locate gradle. Please configure the path to gradle using \'flutter config --gradle-dir\'.'
       );
-      return 1;
     } else {
       printTrace('Using gradle from $gradle.');
     }
@@ -139,17 +139,14 @@ Future<int> buildGradleProject(BuildMode buildMode) async {
       );
       status.stop();
       if (exitcode != 0)
-        return exitcode;
+        throwToolExit('Gradle failed: $exitcode', exitCode: exitcode);
     } catch (error) {
-      printError('$error');
-      return 1;
+      throwToolExit('$error');
     }
 
     gradlew = locateProjectGradlew();
-    if (gradlew == null) {
-      printError('Unable to build android/gradlew.');
-      return 1;
-    }
+    if (gradlew == null)
+      throwToolExit('Unable to build android/gradlew.');
   }
 
   // Run 'gradlew build'.
@@ -161,12 +158,11 @@ Future<int> buildGradleProject(BuildMode buildMode) async {
   );
   status.stop();
 
-  if (exitcode == 0) {
+  if (exitcode != 0)
+    throwToolExit('Gradlew failed: $exitcode', exitCode: exitcode);
+
   File apkFile = new File(gradleAppOut);
   printStatus('Built $gradleAppOut (${getSizeAsMB(apkFile.lengthSync())}).');
-  }
-
-  return exitcode;
 }
 
 class _GradleFile {

packages/flutter_tools/lib/src/base/common.dart

@@ -27,8 +27,8 @@ String _homeDirPath;
 /// where the tool should exit with a clear message to the user
 /// and no stack trace unless the --verbose option is specified.
 /// For example: network errors
-void throwToolExit(String message, { int exitCode }) {
-  throw new ToolExit(message, exitCode: exitCode);
+void throwToolExit(String message, { int exitCode, bool isUnusual: false }) {
+  throw new ToolExit(message, exitCode: exitCode, isUnusual: isUnusual);
 }
 
 /// Specialized exception for expected situations
@@ -36,10 +36,12 @@ void throwToolExit(String message, { int exitCode }) {
 /// and no stack trace unless the --verbose option is specified.
 /// For example: network errors
 class ToolExit implements Exception {
-  ToolExit(this.message, { this.exitCode });
+
+  ToolExit(this.message, { this.exitCode, this.isUnusual: false });
 
   final String message;
   final int exitCode;
+  final bool isUnusual;
 
   @override
   String toString() => "Exception: $message";

packages/flutter_tools/lib/src/base/net.dart

@@ -24,6 +24,7 @@ Future<List<int>> fetchUrl(Uri url) async {
       'Download failed: $url\n'
           '  because (${response.statusCode}) ${response.reasonPhrase}',
       exitCode: kNetworkProblemExitCode,
+      isUnusual: true,
     );
   }
 
@@ -37,6 +38,7 @@ Future<List<int>> fetchUrl(Uri url) async {
     throw new ToolExit(
       'Download failed: $url\n  $e',
       exitCode: kNetworkProblemExitCode,
+      isUnusual: true,
     );
   }
 }

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

@@ -10,6 +10,7 @@ import 'package:meta/meta.dart';
 import '../build_info.dart';
 import '../globals.dart';
 import '../runner/flutter_command.dart';
+import '../base/common.dart';
 import '../base/utils.dart';
 import 'build_apk.dart';
 import 'build_aot.dart';
@@ -33,8 +34,7 @@ class BuildCommand extends FlutterCommand {
 
   @override
   Future<int> verifyThenRunCommand() async {
-    if (!commandValidator())
-      return 1;
+    commandValidator();
     return super.verifyThenRunCommand();
   }
 
@@ -46,8 +46,7 @@ abstract class BuildSubCommand extends FlutterCommand {
   @override
   @mustCallSuper
   Future<int> verifyThenRunCommand() async {
-    if (!commandValidator())
-      return 1;
+    commandValidator();
     return super.verifyThenRunCommand();
   }
 
@@ -82,8 +81,7 @@ class BuildCleanCommand extends FlutterCommand {
 
   @override
   Future<int> verifyThenRunCommand() async {
-    if (!commandValidator())
-      return 1;
+    commandValidator();
     return super.verifyThenRunCommand();
   }
 
@@ -97,10 +95,9 @@ class BuildCleanCommand extends FlutterCommand {
 
     try {
       buildDir.deleteSync(recursive: true);
-      return 0;
     } catch (error) {
-      printError(error.toString());
-      return 1;
+      throwToolExit(error.toString());
     }
+    return 0;
   }
 }

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

@@ -7,6 +7,7 @@ import 'dart:io';
 
 import 'package:path/path.dart' as path;
 
+import '../base/common.dart';
 import '../base/logger.dart';
 import '../base/process.dart';
 import '../base/utils.dart';
@@ -46,10 +47,8 @@ class BuildAotCommand extends BuildSubCommand {
     await super.runCommand();
     String targetPlatform = argResults['target-platform'];
     TargetPlatform platform = getTargetPlatformForName(targetPlatform);
-    if (platform == null) {
-      printError('Unknown platform: $targetPlatform');
-      return 1;
-    }
+    if (platform == null)
+      throwToolExit('Unknown platform: $targetPlatform');
 
     String typeName = path.basename(tools.getEngineArtifactsDirectory(platform, getBuildMode()).path);
     Status status = logger.startProgress('Building AOT snapshot in ${getModeName(getBuildMode())} mode ($typeName)...');
@@ -63,7 +62,7 @@ class BuildAotCommand extends BuildSubCommand {
     status.stop();
 
     if (outputPath == null)
-      return 1;
+      throwToolExit(null);
 
     printStatus('Built to $outputPath${Platform.pathSeparator}.');
     return 0;

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

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import '../android/android_sdk.dart';
 import '../android/gradle.dart';
+import '../base/common.dart';
 import '../base/file_system.dart' show ensureDirectoryExists;
 import '../base/logger.dart';
 import '../base/os.dart';
@@ -227,23 +228,19 @@ class BuildApkCommand extends BuildSubCommand {
     await super.runCommand();
 
     TargetPlatform targetPlatform = _getTargetPlatform(argResults['target-arch']);
-    if (targetPlatform != TargetPlatform.android_arm && getBuildMode() != BuildMode.debug) {
-      printError('Profile and release builds are only supported on ARM targets.');
-      return 1;
-    }
+    if (targetPlatform != TargetPlatform.android_arm && getBuildMode() != BuildMode.debug)
+      throwToolExit('Profile and release builds are only supported on ARM targets.');
 
     if (isProjectUsingGradle()) {
-      if (targetPlatform != TargetPlatform.android_arm) {
-        printError('Gradle builds only support ARM targets.');
-        return 1;
-      }
-      return await buildAndroidWithGradle(
+      if (targetPlatform != TargetPlatform.android_arm)
+        throwToolExit('Gradle builds only support ARM targets.');
+      await buildAndroidWithGradle(
         TargetPlatform.android_arm,
         getBuildMode(),
         target: targetFile
       );
     } else {
-      return await buildAndroid(
+      await buildAndroid(
         targetPlatform,
         getBuildMode(),
         force: true,
@@ -261,6 +258,7 @@ class BuildApkCommand extends BuildSubCommand {
         )
       );
     }
+    return 0;
   }
 }
 
@@ -477,7 +475,7 @@ bool _needsRebuild(
   return false;
 }
 
-Future<int> buildAndroid(
+Future<Null> buildAndroid(
   TargetPlatform platform,
   BuildMode buildMode, {
   bool force: false,
@@ -492,16 +490,13 @@ Future<int> buildAndroid(
   outputFile ??= _defaultOutputPath;
 
   // Validate that we can find an android sdk.
-  if (androidSdk == null) {
-    printError('No Android SDK found. Try setting the ANDROID_HOME environment variable.');
-    return 1;
-  }
+  if (androidSdk == null)
+    throwToolExit('No Android SDK found. Try setting the ANDROID_HOME environment variable.');
 
   List<String> validationResult = androidSdk.validateSdkWellFormed();
   if (validationResult.isNotEmpty) {
     validationResult.forEach(printError);
-    printError('Try re-installing or updating your Android SDK.');
-    return 1;
+    throwToolExit('Try re-installing or updating your Android SDK.');
   }
 
   Map<String, File> extraFiles = <String, File>{};
@@ -522,14 +517,12 @@ Future<int> buildAndroid(
       !force &&
       !_needsRebuild(outputFile, manifest, platform, buildMode, extraFiles)) {
     printTrace('APK up to date; skipping build step.');
-    return 0;
+    return;
   }
 
   if (resources != null) {
-    if (!FileSystemEntity.isDirectorySync(resources)) {
-      printError('Resources directory "$resources" not found.');
-      return 1;
-    }
+    if (!FileSystemEntity.isDirectorySync(resources))
+      throwToolExit('Resources directory "$resources" not found.');
   } else {
     if (FileSystemEntity.isDirectorySync(_kDefaultResourcesPath))
       resources = _kDefaultResourcesPath;
@@ -537,19 +530,16 @@ Future<int> buildAndroid(
 
   _ApkComponents components = await _findApkComponents(platform, buildMode, manifest, resources, extraFiles);
 
-  if (components == null) {
-    printError('Failure building APK: unable to find components.');
-    return 1;
-  }
+  if (components == null)
+    throwToolExit('Failure building APK: unable to find components.');
 
   String typeName = path.basename(tools.getEngineArtifactsDirectory(platform, buildMode).path);
   Status status = logger.startProgress('Building APK in ${getModeName(buildMode)} mode ($typeName)...');
 
   if (flxPath != null && flxPath.isNotEmpty) {
     if (!FileSystemEntity.isFileSync(flxPath)) {
-      printError('FLX does not exist: $flxPath');
-      printError('(Omit the --flx option to build the FLX automatically)');
-      return 1;
+      throwToolExit('FLX does not exist: $flxPath\n'
+        '(Omit the --flx option to build the FLX automatically)');
     }
   } else {
     // Build the FLX.
@@ -559,33 +549,25 @@ Future<int> buildAndroid(
       includeRobotoFonts: false);
 
     if (flxPath == null)
-      return 1;
+      throwToolExit(null);
   }
 
   // Build an AOT snapshot if needed.
   if (isAotBuildMode(buildMode) && aotPath == null) {
     aotPath = await buildAotSnapshot(findMainDartFile(target), platform, buildMode);
-    if (aotPath == null) {
-      printError('Failed to build AOT snapshot');
-      return 1;
-    }
+    if (aotPath == null)
+      throwToolExit('Failed to build AOT snapshot');
   }
 
   if (aotPath != null) {
-    if (!isAotBuildMode(buildMode)) {
-      printError('AOT snapshot can not be used in build mode $buildMode');
-      return 1;
-    }
-    if (!FileSystemEntity.isDirectorySync(aotPath)) {
-      printError('AOT snapshot does not exist: $aotPath');
-      return 1;
-    }
+    if (!isAotBuildMode(buildMode))
+      throwToolExit('AOT snapshot can not be used in build mode $buildMode');
+    if (!FileSystemEntity.isDirectorySync(aotPath))
+      throwToolExit('AOT snapshot does not exist: $aotPath');
     for (String aotFilename in kAotSnapshotFiles) {
       String aotFilePath = path.join(aotPath, aotFilename);
-      if (!FileSystemEntity.isFileSync(aotFilePath)) {
-        printError('Missing AOT snapshot file: $aotFilePath');
-        return 1;
-      }
+      if (!FileSystemEntity.isFileSync(aotFilePath))
+        throwToolExit('Missing AOT snapshot file: $aotFilePath');
       components.extraFiles['assets/$aotFilename'] = new File(aotFilePath);
     }
   }
@@ -593,7 +575,9 @@ Future<int> buildAndroid(
   int result = _buildApk(platform, buildMode, components, flxPath, keystore, outputFile);
   status.stop();
 
-  if (result == 0) {
+  if (result != 0)
+    throwToolExit('Build APK failed ($result)', exitCode: result);
+
   File apkFile = new File(outputFile);
   printTrace('Built $outputFile (${getSizeAsMB(apkFile.lengthSync())}).');
 
@@ -602,34 +586,28 @@ Future<int> buildAndroid(
     'targetBuildType',
     _getTargetBuildTypeToken(platform, buildMode, new File(outputFile))
   );
-  }
-
-  return result;
 }
 
-Future<int> buildAndroidWithGradle(
+Future<Null> buildAndroidWithGradle(
   TargetPlatform platform,
   BuildMode buildMode, {
   bool force: false,
   String target
 }) async {
   // Validate that we can find an android sdk.
-  if (androidSdk == null) {
-    printError('No Android SDK found. Try setting the ANDROID_HOME environment variable.');
-    return 1;
-  }
+  if (androidSdk == null)
+    throwToolExit('No Android SDK found. Try setting the ANDROID_HOME environment variable.');
 
   List<String> validationResult = androidSdk.validateSdkWellFormed();
   if (validationResult.isNotEmpty) {
     validationResult.forEach(printError);
-    printError('Try re-installing or updating your Android SDK.');
-    return 1;
+    throwToolExit('Try re-installing or updating your Android SDK.');
   }
 
   return buildGradleProject(buildMode);
 }
 
-Future<int> buildApk(
+Future<Null> buildApk(
   TargetPlatform platform, {
   String target,
   BuildMode buildMode: BuildMode.debug
@@ -642,10 +620,8 @@ Future<int> buildApk(
       target: target
     );
   } else {
-    if (!FileSystemEntity.isFileSync(_kDefaultAndroidManifestPath)) {
-      printError('Cannot build APK: missing $_kDefaultAndroidManifestPath.');
-      return 1;
-    }
+    if (!FileSystemEntity.isFileSync(_kDefaultAndroidManifestPath))
+      throwToolExit('Cannot build APK: missing $_kDefaultAndroidManifestPath.');
 
     return await buildAndroid(
       platform,

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

@@ -6,7 +6,6 @@ import 'dart:async';
 
 import '../build_info.dart';
 import '../flx.dart';
-import '../globals.dart';
 import 'build.dart';
 
 class BuildFlxCommand extends BuildSubCommand {
@@ -42,7 +41,7 @@ class BuildFlxCommand extends BuildSubCommand {
     await super.runCommand();
     String outputPath = argResults['output-file'];
 
-    return await build(
+    await build(
       mainPath: targetFile,
       manifestPath: argResults['manifest'],
       outputPath: outputPath,
@@ -53,12 +52,7 @@ class BuildFlxCommand extends BuildSubCommand {
       precompiledSnapshot: argResults['precompiled'],
       includeRobotoFonts: argResults['include-roboto-fonts'],
       reportLicensedPackages: argResults['report-licensed-packages']
-    ).then((int result) {
-      if (result == 0)
-        printStatus('Built $outputPath.');
-      else
-        printError('Error building $outputPath: $result.');
-      return result;
-    });
+    );
+    return 0;
   }
 }

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

@@ -7,6 +7,7 @@ import 'dart:async';
 import 'package:path/path.dart' as path;
 
 import '../application_package.dart';
+import '../base/common.dart';
 import '../base/logger.dart';
 import '../base/utils.dart';
 import '../build_info.dart';
@@ -43,17 +44,13 @@ class BuildIOSCommand extends BuildSubCommand {
     defaultBuildMode = forSimulator ? BuildMode.debug : BuildMode.release;
 
     await super.runCommand();
-    if (getCurrentHostPlatform() != HostPlatform.darwin_x64) {
-      printError('Building for iOS is only supported on the Mac.');
-      return 1;
-    }
+    if (getCurrentHostPlatform() != HostPlatform.darwin_x64)
+      throwToolExit('Building for iOS is only supported on the Mac.');
 
     IOSApp app = applicationPackages.getPackageForPlatform(TargetPlatform.ios);
 
-    if (app == null) {
-      printError('Application not configured for iOS');
-      return 1;
-    }
+    if (app == null)
+      throwToolExit('Application not configured for iOS');
 
     bool shouldCodesign = argResults['codesign'];
 
@@ -62,10 +59,8 @@ class BuildIOSCommand extends BuildSubCommand {
         'have to manually codesign before deploying to device.');
     }
 
-    if (forSimulator && !isEmulatorBuildMode(getBuildMode())) {
-      printError('${toTitleCase(getModeName(getBuildMode()))} mode is not supported for emulators.');
-      return 1;
-    }
+    if (forSimulator && !isEmulatorBuildMode(getBuildMode()))
+      throwToolExit('${toTitleCase(getModeName(getBuildMode()))} mode is not supported for emulators.');
 
     String logTarget = forSimulator ? 'simulator' : 'device';
 
@@ -83,8 +78,7 @@ class BuildIOSCommand extends BuildSubCommand {
     if (!result.success) {
       printError('Encountered error while building for $logTarget.');
       diagnoseXcodeBuildFailure(result);
-      printError('');
-      return 1;
+      throwToolExit('');
     }
 
     if (result.output != null)

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

@@ -91,47 +91,39 @@ class DriveCommand extends RunCommandBase {
 
   @override
   Future<int> verifyThenRunCommand() async {
-    if (!commandValidator())
-      return 1;
+    commandValidator();
     return super.verifyThenRunCommand();
   }
 
   @override
   Future<int> runCommand() async {
     String testFile = _getTestFile();
-    if (testFile == null) {
-      return 1;
-    }
+    if (testFile == null)
+      throwToolExit(null);
 
     this._device = await targetDeviceFinder();
-    if (device == null) {
-      return 1;
-    }
+    if (device == null)
+      throwToolExit(null);
 
-    if (await fs.type(testFile) != FileSystemEntityType.FILE) {
-      printError('Test file not found: $testFile');
-      return 1;
-    }
+    if (await fs.type(testFile) != FileSystemEntityType.FILE)
+      throwToolExit('Test file not found: $testFile');
 
     if (!argResults['use-existing-app']) {
       printStatus('Starting application: ${argResults["target"]}');
 
       if (getBuildMode() == BuildMode.release) {
         // This is because we need VM service to be able to drive the app.
-        printError(
+        throwToolExit(
           'Flutter Driver does not support running in release mode.\n'
           '\n'
           'Use --profile mode for testing application performance.\n'
           'Use --debug (default) mode for testing correctness (with assertions).'
         );
-        return 1;
       }
 
       int result = await appStarter(this);
-      if (result != 0) {
-        printError('Application failed to start. Will not run test. Quitting.');
-        return result;
-      }
+      if (result != 0)
+        throwToolExit('Application failed to start ($result). Will not run test. Quitting.', exitCode: result);
     } else {
       printStatus('Will connect to already running application instance.');
     }
@@ -139,11 +131,11 @@ class DriveCommand extends RunCommandBase {
     Cache.releaseLockEarly();
 
     try {
-      return await testRunner(<String>[testFile])
-        .catchError((dynamic error, dynamic stackTrace) {
-          printError('CAUGHT EXCEPTION: $error\n$stackTrace');
-          return 1;
-        });
+      await testRunner(<String>[testFile]);
+    } catch (error, stackTrace) {
+      if (error is ToolExit)
+        rethrow;
+      throwToolExit('CAUGHT EXCEPTION: $error\n$stackTrace');
     } finally {
       if (!argResults['keep-app-running'] && !argResults['use-existing-app']) {
         printStatus('Stopping application instance.');
@@ -157,6 +149,7 @@ class DriveCommand extends RunCommandBase {
         printStatus('Leaving the application running.');
       }
     }
+    return 0;
   }
 
   String _getTestFile() {
@@ -285,14 +278,11 @@ Future<int> startApp(DriveCommand command) async {
   // TODO(devoncarew): We should remove the need to special case here.
   if (command.device is AndroidDevice) {
     printTrace('Building an APK.');
-    int result = await build_apk.buildApk(
+    await build_apk.buildApk(
       command.device.platform,
       target: command.targetFile,
       buildMode: command.getBuildMode()
     );
-
-    if (result != 0)
-      return result;
   }
 
   printTrace('Stopping previously running application, if any.');
@@ -335,13 +325,13 @@ Future<int> startApp(DriveCommand command) async {
 }
 
 /// Runs driver tests.
-typedef Future<int> TestRunner(List<String> testArgs);
+typedef Future<Null> TestRunner(List<String> testArgs);
 TestRunner testRunner = runTests;
 void restoreTestRunner() {
   testRunner = runTests;
 }
 
-Future<int> runTests(List<String> testArgs) async {
+Future<Null> runTests(List<String> testArgs) async {
   printTrace('Running driver tests.');
 
   PackageMap.globalPackagesPath = path.normalize(path.absolute(PackageMap.globalPackagesPath));
@@ -349,7 +339,9 @@ Future<int> runTests(List<String> testArgs) async {
     ..add('--packages=${PackageMap.globalPackagesPath}')
     ..add('-rexpanded');
   String dartVmPath = path.join(dartSdkPath, 'bin', 'dart');
-  return await runCommandAndStreamOutput(<String>[dartVmPath]..addAll(args));
+  int result = await runCommandAndStreamOutput(<String>[dartVmPath]..addAll(args));
+  if (result != 0)
+    throwToolExit('Driver tests failed: $result', exitCode: result);
 }
 
 

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

@@ -6,9 +6,9 @@ import 'dart:async';
 
 import 'package:path/path.dart' as path;
 
+import '../base/common.dart';
 import '../base/process.dart';
 import '../cache.dart';
-import '../globals.dart';
 import '../runner/flutter_command.dart';
 
 class FormatCommand extends FlutterCommand {
@@ -27,18 +27,22 @@ class FormatCommand extends FlutterCommand {
   @override
   Future<int> runCommand() async {
     if (argResults.rest.isEmpty) {
-      printStatus('No files specified to be formatted.');
-      printStatus('');
-      printStatus('To format all files in the current directory tree:');
-      printStatus('${runner.executableName} $name .');
-      printStatus('');
-      printStatus(usage);
-      return 1;
+      throwToolExit(
+        'No files specified to be formatted.\n'
+        '\n'
+        'To format all files in the current directory tree:\n'
+        '${runner.executableName} $name .\n'
+        '\n'
+        '$usage'
+      );
     }
 
     String dartfmt = path.join(
         Cache.flutterRoot, 'bin', 'cache', 'dart-sdk', 'bin', 'dartfmt');
     List<String> cmd = <String>[dartfmt, '-w']..addAll(argResults.rest);
-    return runCommandAndStreamOutput(cmd);
+    int result = await runCommandAndStreamOutput(cmd);
+    if (result != 0)
+      throwToolExit('Formatting failed: $result', exitCode: result);
+    return 0;
   }
 }

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

@@ -5,6 +5,7 @@
 import 'dart:async';
 
 import '../application_package.dart';
+import '../base/common.dart';
 import '../cache.dart';
 import '../device.dart';
 import '../globals.dart';
@@ -21,11 +22,10 @@ class InstallCommand extends FlutterCommand {
 
   @override
   Future<int> verifyThenRunCommand() async {
-    if (!commandValidator())
-      return 1;
+    commandValidator();
     device = await findTargetDevice();
     if (device == null)
-      return 1;
+      throwToolExit('No target device found');
     return super.verifyThenRunCommand();
   }
 
@@ -37,7 +37,9 @@ class InstallCommand extends FlutterCommand {
 
     printStatus('Installing $package to $device...');
 
-    return installApp(device, package) ? 0 : 2;
+    if (!installApp(device, package))
+      throwToolExit('Install failed');
+    return 0;
   }
 }
 

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

@@ -5,6 +5,7 @@
 import 'dart:async';
 import 'dart:io';
 
+import '../base/common.dart';
 import '../cache.dart';
 import '../device.dart';
 import '../globals.dart';
@@ -31,7 +32,7 @@ class LogsCommand extends FlutterCommand {
   Future<int> verifyThenRunCommand() async {
     device = await findTargetDevice();
     if (device == null)
-      return 1;
+      throwToolExit(null);
     return super.verifyThenRunCommand();
   }
 
@@ -74,7 +75,7 @@ class LogsCommand extends FlutterCommand {
     int result = await exitCompleter.future;
     subscription.cancel();
     if (result != 0)
-      printError('Error listening to $logReader logs.');
-    return result;
+      throwToolExit('Error listening to $logReader logs.');
+    return 0;
   }
 }

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

@@ -4,9 +4,9 @@
 
 import 'dart:async';
 
+import '../base/common.dart';
 import '../base/os.dart';
 import '../dart/pub.dart';
-import '../globals.dart';
 import '../runner/flutter_command.dart';
 
 class PackagesCommand extends FlutterCommand {
@@ -26,8 +26,7 @@ class PackagesCommand extends FlutterCommand {
 
   @override
   Future<int> verifyThenRunCommand() async {
-    if (!commandValidator())
-      return 1;
+    commandValidator();
     return super.verifyThenRunCommand();
   }
 
@@ -54,25 +53,22 @@ class PackagesGetCommand extends FlutterCommand {
 
   @override
   Future<int> runCommand() async {
-    if (argResults.rest.length > 1) {
-      printStatus('Too many arguments.');
-      printStatus(usage);
-      return 1;
-    }
+    if (argResults.rest.length > 1)
+      throwToolExit('Too many arguments.\n$usage');
 
     String target = findProjectRoot(
         argResults.rest.length == 1 ? argResults.rest[0] : null);
-    if (target == null) {
-      printStatus('Expected to find project root starting at ' +
+    if (target == null)
+      throwToolExit(
+          'Expected to find project root starting at ' +
           (argResults.rest.length == 1
               ? argResults.rest[0]
-              : 'current working directory'));
-      printStatus(usage);
-      return 1;
-    }
+              : 'current working directory') +
+          '$usage');
 
     // TODO: If the user is using a local build, we should use the packages from their build instead of the cache.
 
-    return pubGet(directory: target, upgrade: upgrade, checkLastModified: false);
+    await pubGet(directory: target, upgrade: upgrade, checkLastModified: false);
+    return 0;
   }
 }

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

@@ -95,12 +95,11 @@ class RunCommand extends RunCommandBase {
     argParser.addFlag('benchmark', negatable: false, hide: !verboseHelp);
 
     commandValidator = () {
-      if (!runningWithPrebuiltApplication) {
-        return commonCommandValidator();
-      }
+      if (!runningWithPrebuiltApplication)
+        commonCommandValidator();
+
       // When running with a prebuilt application, no command validation is
       // necessary.
-      return true;
     };
   }
 
@@ -150,11 +149,10 @@ class RunCommand extends RunCommandBase {
 
   @override
   Future<int> verifyThenRunCommand() async {
-    if (!commandValidator())
-      return 1;
+    commandValidator();
     device = await findTargetDevice();
     if (device == null)
-      return 1;
+      throwToolExit(null);
     return super.verifyThenRunCommand();
   }
 
@@ -173,7 +171,9 @@ class RunCommand extends RunCommandBase {
       AppInstance app = daemon.appDomain.startApp(
         device, Directory.current.path, targetFile, route,
         getBuildMode(), argResults['start-paused'], hotMode);
-      return app.runner.waitForAppToFinish();
+      int result = await app.runner.waitForAppToFinish();
+      if (result != 0)
+        throwToolExit(null, exitCode: result);
     }
 
     int debugPort;
@@ -181,15 +181,12 @@ class RunCommand extends RunCommandBase {
       try {
         debugPort = int.parse(argResults['debug-port']);
       } catch (error) {
-        printError('Invalid port for `--debug-port`: $error');
-        return 1;
+        throwToolExit('Invalid port for `--debug-port`: $error');
       }
     }
 
-    if (device.isLocalEmulator && !isEmulatorBuildMode(getBuildMode())) {
-      printError('${toTitleCase(getModeName(getBuildMode()))} mode is not supported for emulators.');
-      return 1;
-    }
+    if (device.isLocalEmulator && !isEmulatorBuildMode(getBuildMode()))
+      throwToolExit('${toTitleCase(getModeName(getBuildMode()))} mode is not supported for emulators.');
 
     DebuggingOptions options;
 
@@ -204,11 +201,8 @@ class RunCommand extends RunCommandBase {
     }
 
     if (hotMode) {
-      if (!device.supportsHotMode) {
-        printError('Hot mode is not supported by this device. '
-                   'Run with --no-hot.');
-        return 1;
-      }
+      if (!device.supportsHotMode)
+        throwToolExit('Hot mode is not supported by this device. Run with --no-hot.');
     }
 
     String pidFile = argResults['pid-file'];
@@ -238,6 +232,12 @@ class RunCommand extends RunCommandBase {
       );
     }
 
-    return runner.run(route: route, shouldBuild: !runningWithPrebuiltApplication && argResults['build']);
+    int result = await runner.run(
+      route: route,
+      shouldBuild: !runningWithPrebuiltApplication && argResults['build'],
+    );
+    if (result != 0)
+      throwToolExit(null, exitCode: result);
+    return 0;
   }
 }

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

@@ -5,11 +5,12 @@
 import 'dart:async';
 import 'dart:io';
 
-import 'package:flutter_tools/src/device.dart';
 import 'package:http/http.dart' as http;
 import 'package:path/path.dart' as path;
 
+import '../base/common.dart';
 import '../base/utils.dart';
+import '../device.dart';
 import '../globals.dart';
 import '../runner/flutter_command.dart';
 
@@ -53,24 +54,16 @@ class ScreenshotCommand extends FlutterCommand {
   @override
   Future<int> verifyThenRunCommand() async {
     if (argResults[_kSkia] != null) {
-      if (argResults[_kOut] != null && argResults[_kSkiaServe] != null) {
-        printError('Cannot specify both --$_kOut and --$_kSkiaServe');
-        return 1;
-      }
+      if (argResults[_kOut] != null && argResults[_kSkiaServe] != null)
+        throwToolExit('Cannot specify both --$_kOut and --$_kSkiaServe');
     } else {
-      if (argResults[_kSkiaServe] != null) {
-        printError('Must specify --$_kSkia with --$_kSkiaServe');
-        return 1;
-      }
+      if (argResults[_kSkiaServe] != null)
+        throwToolExit('Must specify --$_kSkia with --$_kSkiaServe');
       device = await findTargetDevice();
-      if (device == null) {
-        printError('Must specify --$_kSkia or have a connected device');
-        return 1;
-      }
-      if (!device.supportsScreenshot && argResults[_kSkia] == null) {
-        printError('Screenshot not supported for ${device.name}.');
-        return 1;
-      }
+      if (device == null)
+        throwToolExit('Must specify --$_kSkia or have a connected device');
+      if (!device.supportsScreenshot && argResults[_kSkia] == null)
+        throwToolExit('Screenshot not supported for ${device.name}.');
     }
     return super.verifyThenRunCommand();
   }
@@ -91,14 +84,13 @@ class ScreenshotCommand extends FlutterCommand {
   Future<int> runScreenshot(File outputFile) async {
     outputFile ??= getUniqueFile(Directory.current, 'flutter', 'png');
     try {
-      if (await device.takeScreenshot(outputFile)) {
-        await showOutputFileInfo(outputFile);
-        return 0;
-      }
+      if (!await device.takeScreenshot(outputFile))
+        throwToolExit('Screenshot failed');
     } catch (error) {
-      printError('Error taking screenshot: $error');
+      throwToolExit('Error taking screenshot: $error');
     }
-    return 1;
+    await showOutputFileInfo(outputFile);
+    return 0;
   }
 
   Future<int> runSkia(File outputFile) async {
@@ -106,26 +98,20 @@ class ScreenshotCommand extends FlutterCommand {
         port: int.parse(argResults[_kSkia]),
         path: '/skp');
 
-    void printErrorHelpText() {
-      printError('');
-      printError('Be sure the --$_kSkia= option specifies the diagnostic server port, not the observatory port.');
-      printError('To find the diagnostic server port number, use "flutter run --verbose"');
-      printError('and look for "Diagnostic server listening on" in the output.');
-    }
+    const String errorHelpText =
+        'Be sure the --$_kSkia= option specifies the diagnostic server port, not the observatory port.\n'
+        'To find the diagnostic server port number, use "flutter run --verbose"\n'
+        'and look for "Diagnostic server listening on" in the output.';
 
     http.StreamedResponse skpResponse;
     try {
       skpResponse = await new http.Request('GET', skpUri).send();
     } on SocketException catch (e) {
-      printError('Skia screenshot failed: $skpUri\n$e');
-      printErrorHelpText();
-      return 1;
+      throwToolExit('Skia screenshot failed: $skpUri\n$e\n\n$errorHelpText');
     }
     if (skpResponse.statusCode != HttpStatus.OK) {
       String error = await skpResponse.stream.toStringStream().join();
-      printError('Error: $error');
-      printErrorHelpText();
-      return 1;
+      throwToolExit('Error: $error\n\n$errorHelpText');
     }
 
     if (argResults[_kSkiaServe] != null) {
@@ -136,11 +122,8 @@ class ScreenshotCommand extends FlutterCommand {
           'file', skpResponse.stream, skpResponse.contentLength));
 
       http.StreamedResponse postResponse = await postRequest.send();
-      if (postResponse.statusCode != HttpStatus.OK) {
-        printError('Failed to post Skia picture to skiaserve.');
-        printErrorHelpText();
-        return 1;
-      }
+      if (postResponse.statusCode != HttpStatus.OK)
+        throwToolExit('Failed to post Skia picture to skiaserve.\n\n$errorHelpText');
     } else {
       outputFile ??= getUniqueFile(Directory.current, 'flutter', 'skp');
       IOSink sink = outputFile.openWrite();
@@ -149,12 +132,8 @@ class ScreenshotCommand extends FlutterCommand {
       await showOutputFileInfo(outputFile);
       if (await outputFile.length() < 1000) {
         String content = await outputFile.readAsString();
-        if (content.startsWith('{"jsonrpc":"2.0", "error"')) {
-          printError('');
-          printError('It appears the output file contains an error message, not valid skia output.');
-          printErrorHelpText();
-          return 1;
-        }
+        if (content.startsWith('{"jsonrpc":"2.0", "error"'))
+          throwToolExit('\nIt appears the output file contains an error message, not valid skia output.\n\n$errorHelpText');
       }
     }
     return 0;

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

@@ -53,9 +53,7 @@ class UpdatePackagesCommand extends FlutterCommand {
       final bool upgrade = argResults['upgrade'];
 
       for (Directory dir in runner.getRepoPackages()) {
-        int code = await pubGet(directory: dir.path, upgrade: upgrade, checkLastModified: false);
-        if (code != 0)
-          throw code;
+        await pubGet(directory: dir.path, upgrade: upgrade, checkLastModified: false);
         count++;
       }
 

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

@@ -72,11 +72,7 @@ class UpgradeCommand extends FlutterCommand {
     String projRoot = findProjectRoot();
     if (projRoot != null) {
       printStatus('');
-      code = await pubGet(
-          directory: projRoot, upgrade: true, checkLastModified: false);
-
-      if (code != 0)
-        return code;
+      await pubGet(directory: projRoot, upgrade: true, checkLastModified: false);
     }
 
     // Run a doctor check in case system requirements have changed.

packages/flutter_tools/lib/src/dart/pub.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 
 import 'package:path/path.dart' as path;
 
+import '../base/common.dart';
 import '../base/logger.dart';
 import '../base/process.dart';
 import '../cache.dart';
@@ -25,7 +26,7 @@ bool _shouldRunPubGet({ File pubSpecYaml, File dotPackages }) {
   return false;
 }
 
-Future<int> pubGet({
+Future<Null> pubGet({
   String directory,
   bool skipIfAbsent: false,
   bool upgrade: false,
@@ -38,10 +39,9 @@ Future<int> pubGet({
   File dotPackages = new File(path.join(directory, '.packages'));
 
   if (!pubSpecYaml.existsSync()) {
-    if (skipIfAbsent)
-      return 0;
-    printError('$directory: no pubspec.yaml found');
-    return 1;
+    if (!skipIfAbsent)
+      throwToolExit('$directory: no pubspec.yaml found');
+    return;
   }
 
   if (!checkLastModified || _shouldRunPubGet(pubSpecYaml: pubSpecYaml, dotPackages: dotPackages)) {
@@ -55,14 +55,13 @@ Future<int> pubGet({
     );
     status.stop();
     if (code != 0)
-      return code;
+      throwToolExit('pub $command failed ($code)', exitCode: code);
   }
 
   if (dotPackages.existsSync() && dotPackages.lastModifiedSync().isAfter(pubSpecYaml.lastModifiedSync()))
-    return 0;
+    return;
 
-  printError('$directory: pubspec.yaml and .packages are in an inconsistent state');
-  return 1;
+  throwToolExit('$directory: pubspec.yaml and .packages are in an inconsistent state');
 }
 
 String _filterOverrideWarnings(String str) {

packages/flutter_tools/lib/src/flx.dart

@@ -8,6 +8,7 @@ import 'dart:io';
 import 'package:path/path.dart' as path;
 
 import 'asset.dart';
+import 'base/common.dart';
 import 'base/file_system.dart' show ensureDirectoryExists;
 import 'base/process.dart';
 import 'dart/package_map.dart';
@@ -59,18 +60,17 @@ Future<String> buildFlx({
   bool precompiledSnapshot: false,
   bool includeRobotoFonts: true
 }) async {
-  int result;
-  result = await build(
+  await build(
     snapshotPath: defaultSnapshotPath,
     outputPath: defaultFlxOutputPath,
     mainPath: mainPath,
     precompiledSnapshot: precompiledSnapshot,
     includeRobotoFonts: includeRobotoFonts
   );
-  return result == 0 ? defaultFlxOutputPath : null;
+  return defaultFlxOutputPath;
 }
 
-Future<int> build({
+Future<Null> build({
   String snapshotterPath,
   String mainPath: defaultMainPath,
   String manifestPath: defaultManifestPath,
@@ -104,10 +104,8 @@ Future<int> build({
       depfilePath: depfilePath,
       packages: packagesPath
     );
-    if (result != 0) {
-      printError('Failed to run the Flutter compiler. Exit code: $result');
-      return result;
-    }
+    if (result != 0)
+      throwToolExit('Failed to run the Flutter compiler. Exit code: $result', exitCode: result);
 
     snapshotFile = new File(snapshotPath);
   }
@@ -124,7 +122,7 @@ Future<int> build({
   );
 }
 
-Future<int> assemble({
+Future<Null> assemble({
   String manifestPath,
   File snapshotFile,
   String outputPath,
@@ -150,9 +148,8 @@ Future<int> assemble({
     includeRobotoFonts: includeRobotoFonts,
     reportLicensedPackages: reportLicensedPackages
   );
-  if (result != 0) {
-    return result;
-  }
+  if (result != 0)
+    throwToolExit('Error building $outputPath: $result', exitCode: result);
 
   ZipBuilder zipBuilder = new ZipBuilder();
 
@@ -168,6 +165,4 @@ Future<int> assemble({
   zipBuilder.createZip(new File(outputPath), new Directory(workingDirPath));
 
   printTrace('Built $outputPath.');
-
-  return 0;
 }

packages/flutter_tools/lib/src/hot.dart

@@ -199,14 +199,11 @@ class HotRunner extends ResidentRunner {
     if (shouldBuild && device is AndroidDevice) {
       printTrace('Running build command.');
 
-      int result = await buildApk(
+      await buildApk(
         device.platform,
         target: target,
         buildMode: debuggingOptions.buildMode
       );
-
-      if (result != 0)
-        return result;
     }
 
     // TODO(devoncarew): Move this into the device.startApp() impls.

packages/flutter_tools/lib/src/ios/simulators.dart

@@ -421,9 +421,12 @@ class IOSSimulator extends Device {
     if (!prebuiltApplication) {
       printTrace('Building ${app.name} for $id.');
 
-      if (!(await _setupUpdatedApplicationBundle(app)))
+      try {
+        await _setupUpdatedApplicationBundle(app);
+      } on ToolExit {
         return new LaunchResult.failed();
       }
+    }
 
     ProtocolDiscovery observatoryDiscovery;
 
@@ -496,45 +499,33 @@ class IOSSimulator extends Device {
     return isInstalled && isRunning;
   }
 
-  Future<bool> _setupUpdatedApplicationBundle(ApplicationPackage app) async {
-    bool sideloadResult = await _sideloadUpdatedAssetsForInstalledApplicationBundle(app);
-
-    if (!sideloadResult)
-      return false;
+  Future<Null> _setupUpdatedApplicationBundle(ApplicationPackage app) async {
+    await _sideloadUpdatedAssetsForInstalledApplicationBundle(app);
 
     if (!_applicationIsInstalledAndRunning(app))
       return _buildAndInstallApplicationBundle(app);
-
-    return true;
   }
 
-  Future<bool> _buildAndInstallApplicationBundle(ApplicationPackage app) async {
+  Future<Null> _buildAndInstallApplicationBundle(ApplicationPackage app) async {
     // Step 1: Build the Xcode project.
     // The build mode for the simulator is always debug.
     XcodeBuildResult buildResult = await buildXcodeProject(app: app, mode: BuildMode.debug, buildForDevice: false);
-    if (!buildResult.success) {
-      printError('Could not build the application for the simulator.');
-      return false;
-    }
+    if (!buildResult.success)
+      throwToolExit('Could not build the application for the simulator.');
 
     // Step 2: Assert that the Xcode project was successfully built.
     IOSApp iosApp = app;
     Directory bundle = new Directory(iosApp.simulatorBundlePath);
     bool bundleExists = await bundle.exists();
-    if (!bundleExists) {
-      printError('Could not find the built application bundle at ${bundle.path}.');
-      return false;
-    }
+    if (!bundleExists)
+      throwToolExit('Could not find the built application bundle at ${bundle.path}.');
 
     // Step 3: Install the updated bundle to the simulator.
     SimControl.instance.install(id, path.absolute(bundle.path));
-    return true;
   }
 
-  Future<bool> _sideloadUpdatedAssetsForInstalledApplicationBundle(
-      ApplicationPackage app) async {
-    return (await flx.build(precompiledSnapshot: true)) == 0;
-  }
+  Future<Null> _sideloadUpdatedAssetsForInstalledApplicationBundle(ApplicationPackage app) =>
+      flx.build(precompiledSnapshot: true);
 
   @override
   Future<bool> stopApp(ApplicationPackage app) async {

packages/flutter_tools/lib/src/run.dart

@@ -95,14 +95,11 @@ class RunAndStayResident extends ResidentRunner {
     if (shouldBuild && device is AndroidDevice) {
       printTrace('Running build command.');
 
-      int result = await buildApk(
+      await buildApk(
         device.platform,
         target: target,
         buildMode: debuggingOptions.buildMode
       );
-
-      if (result != 0)
-        return result;
     }
 
     // TODO(devoncarew): Move this into the device.startApp() impls.

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -135,11 +135,8 @@ abstract class FlutterCommand extends Command {
     // package is available in the flutter cache for pub to find.
     await cache.updateAll();
 
-    if (shouldRunPub) {
-      int exitCode = await pubGet();
-      if (exitCode != 0)
-        return exitCode;
-    }
+    if (shouldRunPub)
+      await pubGet();
 
     setupApplicationPackages();
 

packages/flutter_tools/test/drive_test.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 
 import 'package:file/file.dart';
 import 'package:flutter_tools/src/android/android_device.dart';
+import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/os.dart';
@@ -58,19 +59,19 @@ void main() {
       restoreTargetDeviceFinder();
     });
 
-    testUsingContext('returns 1 when test file is not found', () {
+    testUsingContext('returns 1 when test file is not found', () async {
       withMockDevice();
       List<String> args = <String>[
         'drive',
         '--target=/some/app/test/e2e.dart',
       ];
-      return createTestCommandRunner(command).run(args).then((int code) {
-        expect(code, 1);
-        BufferLogger buffer = logger;
-        expect(buffer.errorText, contains(
-          'Test file not found: /some/app/test_driver/e2e_test.dart'
-        ));
-      });
+      try {
+        await createTestCommandRunner(command).run(args);
+        fail('Expect exception');
+      } on ToolExit catch (e) {
+        expect(e.exitCode ?? 1, 1);
+        expect(e.message, contains('Test file not found: /some/app/test_driver/e2e_test.dart'));
+      }
     });
 
     testUsingContext('returns 1 when app fails to run', () async {
@@ -88,13 +89,13 @@ void main() {
         'drive',
         '--target=$testApp',
       ];
-      return createTestCommandRunner(command).run(args).then((int code) {
-        expect(code, 1);
-        BufferLogger buffer = logger;
-        expect(buffer.errorText, contains(
-          'Application failed to start. Will not run test. Quitting.'
-        ));
-      });
+      try {
+        await createTestCommandRunner(command).run(args);
+        fail('Expect exception');
+      } on ToolExit catch (e) {
+        expect(e.exitCode, 1);
+        expect(e.message, contains('Application failed to start (1). Will not run test. Quitting.'));
+      }
     });
 
     testUsingContext('returns 1 when app file is outside package', () async {
@@ -106,13 +107,15 @@ void main() {
         'drive',
         '--target=$appFile',
       ];
-      return createTestCommandRunner(command).run(args).then((int code) {
-        expect(code, 1);
-        BufferLogger buffer = logger;
-        expect(buffer.errorText, contains(
-          'Application file $appFile is outside the package directory $packageDir'
+      try {
+        await createTestCommandRunner(command).run(args);
+        fail('Expect exception');
+      } on ToolExit catch (e) {
+        expect(e.exitCode ?? 1, 1);
+        expect(testLogger.errorText, contains(
+          'Application file $appFile is outside the package directory $packageDir',
         ));
-      });
+      }
     });
 
     testUsingContext('returns 1 when app file is in the root dir', () async {
@@ -124,14 +127,16 @@ void main() {
         'drive',
         '--target=$appFile',
       ];
-      return createTestCommandRunner(command).run(args).then((int code) {
-        expect(code, 1);
-        BufferLogger buffer = logger;
-        expect(buffer.errorText, contains(
+      try {
+        await createTestCommandRunner(command).run(args);
+        fail('Expect exception');
+      } on ToolExit catch (e) {
+        expect(e.exitCode ?? 1, 1);
+        expect(testLogger.errorText, contains(
           'Application file main.dart must reside in one of the '
-          'sub-directories of the package structure, not in the root directory.'
+          'sub-directories of the package structure, not in the root directory.',
         ));
-      });
+      }
     });
 
     testUsingContext('returns 0 when test ends successfully', () async {
@@ -175,9 +180,9 @@ void main() {
       appStarter = expectAsync((_) {
         return new Future<int>.value(0);
       });
-      testRunner = expectAsync((_) {
-        return new Future<int>.value(123);
-      });
+      testRunner = (_) {
+        throwToolExit(null, exitCode: 123);
+      };
       appStopper = expectAsync((_) {
         return new Future<int>.value(0);
       });
@@ -190,14 +195,15 @@ void main() {
         'drive',
         '--target=$testApp',
       ];
-      return createTestCommandRunner(command).run(args).then((int code) {
-        expect(code, 123);
-        BufferLogger buffer = logger;
-        expect(buffer.errorText, isEmpty);
-      });
+      try {
+        await createTestCommandRunner(command).run(args);
+        fail('Expect exception');
+      } on ToolExit catch (e) {
+        expect(e.exitCode ?? 1, 123);
+        expect(e.message, isNull);
+      }
     });
 
-
     group('findTargetDevice', () {
       testUsingContext('uses specified device', () async {
         testDeviceManager.specifiedDeviceId = '123';

packages/flutter_tools/test/logs_test.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/commands/logs.dart';
 import 'package:test/test.dart';
 
@@ -11,12 +12,15 @@ import 'src/mocks.dart';
 
 void main() {
   group('logs', () {
-    testUsingContext('fail with a bad device id', () {
+    testUsingContext('fail with a bad device id', () async {
       LogsCommand command = new LogsCommand();
       applyMocksToCommand(command);
-      return createTestCommandRunner(command).run(<String>['-d', 'abc123', 'logs']).then((int code) {
-        expect(code, 1);
-      });
+      try {
+        await createTestCommandRunner(command).run(<String>['-d', 'abc123', 'logs']);
+        fail('Expect exception');
+      } on ToolExit catch (e) {
+        expect(e.exitCode ?? 1, 1);
+      }
     });
   });
 }

packages/flutter_tools/test/run_test.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/commands/run.dart';
 import 'package:test/test.dart';
 
@@ -11,12 +12,15 @@ import 'src/mocks.dart';
 
 void main() {
   group('run', () {
-    testUsingContext('fails when target not found', () {
+    testUsingContext('fails when target not found', () async {
       RunCommand command = new RunCommand();
       applyMocksToCommand(command);
-      return createTestCommandRunner(command).run(<String>['run', '-t', 'abc123']).then((int code) {
-        expect(code, 1);
-      });
+      try {
+        await createTestCommandRunner(command).run(<String>['run', '-t', 'abc123']);
+        fail('Expect exception');
+      } on ToolExit catch (e) {
+        expect(e.exitCode ?? 1, 1);
+      }
     });
   });
 }