[O] Remove many timeouts. (#23531)

* Remove many timeouts.

These are essentially self-inflicted race conditions. Instead of timeouts we're going to try a more verbose logging mechanism that points out when things are taking a long time.

* Get the attach tests to pass.

* Apply review comments from Todd

* More review comment fixes

* Put back the extended timeouts here now that I know why we have them...

dev/devicelab/bin/tasks/run_machine_concurrent_hot_reload.dart

@@ -50,20 +50,22 @@ void main() {
           '--verbose',
           '-d',
           device.deviceId,
-          'lib/commands.dart'
+          'lib/commands.dart',
         ],
       );
-      final StreamController<String> stdout =
-          StreamController<String>.broadcast();
+      final StreamController<String> stdout = StreamController<String>.broadcast();
       transformToLines(run.stdout).listen((String line) {
         print('run:stdout: $line');
         stdout.add(line);
         final dynamic json = parseFlutterResponse(line);
-        if (json != null && json['event'] == 'app.debugPort') {
+        if (json != null) {
+          if (json['event'] == 'app.debugPort') {
             vmServicePort = Uri.parse(json['params']['wsUri']).port;
             print('service protocol connection available at port $vmServicePort');
-        } else if (json != null && json['event'] == 'app.started') {
+          } else if (json['event'] == 'app.started') {
             appId = json['params']['appId'];
+            print('application identifier is $appId');
+          }
         }
         if (vmServicePort != null && appId != null && !ready.isCompleted) {
           print('run: ready!');
@@ -73,6 +75,7 @@ void main() {
       });
       transformToLines(run.stderr).listen((String line) {
         stderr.writeln('run:stderr: $line');
+        ok = false;
       });
       run.exitCode.then<void>((int exitCode) {
         ok = false;
@@ -81,17 +84,15 @@ void main() {
       if (!ok)
         throw 'Failed to run test app.';
 
-      final VMServiceClient client =
-          VMServiceClient.connect('ws://localhost:$vmServicePort/ws');
+      final VMServiceClient client = VMServiceClient.connect(
+        'ws://localhost:$vmServicePort/ws'
+      );
 
       int id = 1;
-      Future<Map<String, dynamic>> sendRequest(
-          String method, dynamic params) async {
+      Future<Map<String, dynamic>> sendRequest(String method, dynamic params) async {
         final int requestId = id++;
-        final Completer<Map<String, dynamic>> response =
-            Completer<Map<String, dynamic>>();
-        final StreamSubscription<String> responseSubscription =
-            stdout.stream.listen((String line) {
+        final Completer<Map<String, dynamic>> response = Completer<Map<String, dynamic>>();
+        final StreamSubscription<String> responseSubscription = stdout.stream.listen((String line) {
           final Map<String, dynamic> json = parseFlutterResponse(line);
           if (json != null && json['id'] == requestId)
             response.complete(json);
@@ -110,27 +111,35 @@ void main() {
       }
 
       print('test: sending two hot reloads...');
-      final Future<dynamic> hotReload1 = sendRequest('app.restart',
-          <String, dynamic>{'appId': appId, 'fullRestart': false});
-      final Future<dynamic> hotReload2 = sendRequest('app.restart',
-          <String, dynamic>{'appId': appId, 'fullRestart': false});
-      final Future<List<dynamic>> reloadRequests =
-          Future.wait<dynamic>(<Future<dynamic>>[hotReload1, hotReload2]);
-      final dynamic results = await Future
-          .any<dynamic>(<Future<dynamic>>[run.exitCode, reloadRequests]);
+      final Future<dynamic> hotReload1 = sendRequest(
+        'app.restart',
+        <String, dynamic>{'appId': appId, 'fullRestart': false},
+      );
+      final Future<dynamic> hotReload2 = sendRequest(
+        'app.restart',
+        <String, dynamic>{'appId': appId, 'fullRestart': false},
+      );
+      final Future<List<dynamic>> reloadRequests = Future.wait<dynamic>(<Future<dynamic>>[
+        hotReload1,
+        hotReload2,
+      ]);
+      final dynamic results = await Future.any<dynamic>(<Future<dynamic>>[
+        run.exitCode,
+        reloadRequests,
+      ]);
 
       if (!ok)
-        throw 'App crashed during hot reloads.';
+        throw 'App failed or crashed during hot reloads.';
 
       final List<dynamic> responses = results;
-      final List<dynamic> errorResponses =
-          responses.where((dynamic r) => r['error'] != null).toList();
-      final List<dynamic> successResponses = responses
-          .where((dynamic r) =>
-              r['error'] == null &&
+      final List<dynamic> errorResponses = responses.where(
+        (dynamic r) => r['error'] != null
+      ).toList();
+      final List<dynamic> successResponses = responses.where(
+        (dynamic r) => r['error'] == null &&
                        r['result'] != null &&
-              r['result']['code'] == 0)
-          .toList();
+                       r['result']['code'] == 0
+      ).toList();
 
       if (errorResponses.length != 1)
         throw 'Did not receive the expected (exactly one) hot reload error response.';
@@ -140,8 +149,10 @@ void main() {
       if (successResponses.length != 1)
         throw 'Did not receive the expected (exactly one) successful hot reload response.';
 
-      final dynamic hotReload3 = await sendRequest('app.restart',
-          <String, dynamic>{'appId': appId, 'fullRestart': false});
+      final dynamic hotReload3 = await sendRequest(
+        'app.restart',
+        <String, dynamic>{'appId': appId, 'fullRestart': false},
+      );
       if (hotReload3['error'] != null)
         throw 'Received an error response from a hot reload after all other hot reloads had completed.';
 
@@ -150,7 +161,7 @@ void main() {
       if (result != 0)
         throw 'Received unexpected exit code $result from run process.';
       print('test: validating that the app has in fact closed...');
-      await client.done.timeout(const Duration(seconds: 5));
+      await client.done;
     });
     return TaskResult.success(null);
   });

dev/integration_tests/external_ui/test_driver/main_test.dart

@@ -29,7 +29,7 @@ Future<void> main() async {
       final SerializableFinder summary = find.byValueKey('summary');
 
       // Wait for calibration to complete and fab to appear.
-      await driver.waitFor(fab, timeout: const Duration(seconds: 40));
+      await driver.waitFor(fab);
 
       final String calibrationResult = await driver.getText(summary);
       final Match matchCalibration = calibrationRegExp.matchAsPrefix(calibrationResult);
@@ -59,7 +59,7 @@ Future<void> main() async {
       expect(double.parse(matchFast.group(1)), closeTo(flutterFrameRate * 2.0, 5.0));
       expect(double.parse(matchFast.group(2)), closeTo(flutterFrameRate, 10.0));
       expect(int.parse(matchFast.group(3)), 1);
-    }, timeout: const Timeout(Duration(minutes: 1)));
+    });
 
     tearDownAll(() async {
       driver?.close();

packages/flutter_driver/lib/src/common/message.dart

@@ -9,16 +9,24 @@ import 'package:meta/meta.dart';
 abstract class Command {
   /// Abstract const constructor. This constructor enables subclasses to provide
   /// const constructors so that they can be used in const expressions.
-  const Command({ Duration timeout })
-      : timeout = timeout ?? const Duration(seconds: 5);
+  const Command({ this.timeout });
 
   /// Deserializes this command from the value generated by [serialize].
   Command.deserialize(Map<String, String> json)
-      : timeout = Duration(milliseconds: int.parse(json['timeout']));
+      : timeout = _parseTimeout(json);
+
+  static Duration _parseTimeout(Map<String, String> json) {
+    final String timeout = json['timeout'];
+    if (timeout == null)
+      return null;
+    return Duration(milliseconds: int.parse(timeout));
+  }
 
   /// The maximum amount of time to wait for the command to complete.
   ///
-  /// Defaults to 5 seconds.
+  /// Defaults to no timeout, because it is common for operations to take oddly
+  /// long in test environments (e.g. because the test host is overloaded), and
+  /// having timeouts essentially means having race conditions.
   final Duration timeout;
 
   /// Identifies the type of the command object and of the handler.
@@ -28,7 +36,7 @@ abstract class Command {
   @mustCallSuper
   Map<String, String> serialize() => <String, String>{
     'command': kind,
-    'timeout': '${timeout.inMilliseconds}',
+    'timeout': timeout == null ? null : '${timeout.inMilliseconds}',
   };
 }
 

packages/flutter_driver/lib/src/extension/extension.dart

@@ -177,7 +177,10 @@ class FlutterDriverExtension {
       if (commandHandler == null || commandDeserializer == null)
         throw 'Extension $_extensionMethod does not support command $commandKind';
       final Command command = commandDeserializer(params);
-      final Result response = await commandHandler(command).timeout(command.timeout);
+      Future<Result> responseFuture = commandHandler(command);
+      if (command.timeout != null)
+        responseFuture = responseFuture.timeout(command.timeout);
+      final Result response = await responseFuture;
       return _makeResponse(response?.toJson());
     } on TimeoutException catch (error, stackTrace) {
       final String msg = 'Timeout while executing $commandKind: $error\n$stackTrace';

packages/flutter_driver/test/flutter_driver_test.dart

@@ -11,13 +11,13 @@ import 'package:flutter_driver/src/driver/timeline.dart';
 import 'package:json_rpc_2/json_rpc_2.dart' as rpc;
 import 'package:mockito/mockito.dart';
 import 'package:vm_service_client/vm_service_client.dart';
+import 'package:quiver/testing/async.dart';
 
 import 'common.dart';
 
 /// Magical timeout value that's different from the default.
 const Duration _kTestTimeout = Duration(milliseconds: 1234);
 const String _kSerializedTestTimeout = '1234';
-const Duration _kDefaultCommandTimeout = Duration(seconds: 5);
 
 void main() {
   group('FlutterDriver.connect', () {
@@ -358,17 +358,19 @@ void main() {
 
     group('sendCommand error conditions', () {
       test('local timeout', () async {
+        final List<String> log = <String>[];
+        final StreamSubscription<LogRecord> logSub = flutterDriverLog.listen((LogRecord s) => log.add(s.toString()));
         when(mockIsolate.invokeExtension(any, any)).thenAnswer((Invocation i) {
-          // completer never competed to trigger timeout
+          // completer never completed to trigger timeout
           return Completer<Map<String, dynamic>>().future;
         });
-        try {
-          await driver.waitFor(find.byTooltip('foo'), timeout: const Duration(milliseconds: 100));
-          fail('expected an exception');
-        } catch (error) {
-          expect(error is DriverError, isTrue);
-          expect(error.message, 'Failed to fulfill WaitFor: Flutter application not responding');
-        }
+        FakeAsync().run((FakeAsync time) {
+          driver.waitFor(find.byTooltip('foo'));
+          expect(log, <String>[]);
+          time.elapse(const Duration(hours: 1));
+        });
+        expect(log, <String>['[warning] FlutterDriver: waitFor message is taking a long time to complete...']);
+        await logSub.cancel();
       });
 
       test('remote error', () async {
@@ -389,7 +391,6 @@ void main() {
   });
 
   group('FlutterDriver with custom timeout', () {
-    const double kTestMultiplier = 3.0;
     MockVMServiceClient mockClient;
     MockPeer mockPeer;
     MockIsolate mockIsolate;
@@ -399,21 +400,21 @@ void main() {
       mockClient = MockVMServiceClient();
       mockPeer = MockPeer();
       mockIsolate = MockIsolate();
-      driver = FlutterDriver.connectedTo(mockClient, mockPeer, mockIsolate, timeoutMultiplier: kTestMultiplier);
+      driver = FlutterDriver.connectedTo(mockClient, mockPeer, mockIsolate);
     });
 
-    test('multiplies the timeout', () async {
+    test('GetHealth has no default timeout', () async {
       when(mockIsolate.invokeExtension(any, any)).thenAnswer((Invocation i) {
         expect(i.positionalArguments[1], <String, String>{
           'command': 'get_health',
-          'timeout': '${(_kDefaultCommandTimeout * kTestMultiplier).inMilliseconds}',
+          'timeout': null,
         });
         return makeMockResponse(<String, dynamic>{'status': 'ok'});
       });
       await driver.checkHealth();
     });
 
-    test('does not multiply explicit timeouts', () async {
+    test('does not interfere with explicit timeouts', () async {
       when(mockIsolate.invokeExtension(any, any)).thenAnswer((Invocation i) {
         expect(i.positionalArguments[1], <String, String>{
           'command': 'get_health',

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

@@ -88,15 +88,13 @@ class AndroidDevice extends Device {
           propCommand,
           stdoutEncoding: latin1,
           stderrEncoding: latin1,
-        ).timeout(const Duration(seconds: 5));
+        );
         if (result.exitCode == 0) {
           _properties = parseAdbDeviceProperties(result.stdout);
         } else {
           printError('Error retrieving device properties for $name:');
           printError(result.stderr);
         }
-      } on TimeoutException catch (_) {
-        throwToolExit('adb not responding');
       } on ProcessException catch (error) {
         printError('Error retrieving device properties for $name: $error');
       }
@@ -279,7 +277,7 @@ class AndroidDevice extends Device {
     if (!await _checkForSupportedAdbVersion() || !await _checkForSupportedAndroidVersion())
       return false;
 
-    final Status status = logger.startProgress('Installing ${fs.path.relative(apk.file.path)}...', expectSlowOperation: true);
+    final Status status = logger.startProgress('Installing ${fs.path.relative(apk.file.path)}...', timeout: kSlowOperation);
     final RunResult installResult = await runAsync(adbCommandForDevice(<String>['install', '-t', '-r', apk.file.path]));
     status.stop();
     // Some versions of adb exit with exit code 0 even on failure :(

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

@@ -51,9 +51,10 @@ class AndroidEmulator extends Emulator {
                 throw '${runResult.stdout}\n${runResult.stderr}'.trimRight();
               }
             });
-    // emulator continues running on a successful launch so if we
-    // haven't quit within 3 seconds we assume that's a success and just
-    // return.
+    // The emulator continues running on a successful launch, so if it hasn't
+    // quit within 3 seconds we assume that's a success and just return. This
+    // means that on a slow machine, a failure that takes more than three
+    // seconds won't be recognized as such... :-/
     return Future.any<void>(<Future<void>>[
       launchResult,
       Future<void>.delayed(const Duration(seconds: 3))

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

@@ -50,9 +50,15 @@ class AndroidWorkflow implements Workflow {
 class AndroidValidator extends DoctorValidator {
   AndroidValidator(): super('Android toolchain - develop for Android devices',);
 
+  @override
+  String get slowWarning => '${_task ?? 'This'} is taking a long time...';
+  String _task;
+
   /// Returns false if we cannot determine the Java version or if the version
   /// is not compatible.
   Future<bool> _checkJavaVersion(String javaBinary, List<ValidationMessage> messages) async {
+    _task = 'Checking Java status';
+    try {
       if (!processManager.canRun(javaBinary)) {
         messages.add(ValidationMessage.error(userMessages.androidCantRunJavaBinary(javaBinary)));
         return false;
@@ -76,6 +82,9 @@ class AndroidValidator extends DoctorValidator {
       messages.add(ValidationMessage(userMessages.androidJavaVersion(javaVersion)));
       // TODO(johnmccutchan): Validate version.
       return true;
+    } finally {
+      _task = null;
+    }
   }
 
   @override
@@ -149,6 +158,9 @@ class AndroidValidator extends DoctorValidator {
 class AndroidLicenseValidator extends DoctorValidator {
   AndroidLicenseValidator(): super('Android license subvalidator',);
 
+  @override
+  String get slowWarning => 'Checking Android licenses is taking an unexpectedly long time...';
+
   @override
   Future<ValidationResult> validate() async {
     final List<ValidationMessage> messages = <ValidationMessage>[];
@@ -208,10 +220,8 @@ class AndroidLicenseValidator extends DoctorValidator {
   Future<LicensesAccepted> get licensesAccepted async {
     LicensesAccepted status;
 
-    void _onLine(String line) {
-      if (status == null && licenseAccepted.hasMatch(line)) {
-        status = LicensesAccepted.all;
-      } else if (licenseCounts.hasMatch(line)) {
+    void _handleLine(String line) {
+      if (licenseCounts.hasMatch(line)) {
         final Match match = licenseCounts.firstMatch(line);
         if (match.group(1) != match.group(2)) {
           status = LicensesAccepted.some;
@@ -219,9 +229,12 @@ class AndroidLicenseValidator extends DoctorValidator {
           status = LicensesAccepted.none;
         }
       } else if (licenseNotAccepted.hasMatch(line)) {
-        // In case the format changes, a more general match will keep doctor
-        // mostly working.
+        // The licenseNotAccepted pattern is trying to match the same line as
+        // licenseCounts, but is more general. In case the format changes, a
+        // more general match may keep doctor mostly working.
         status = LicensesAccepted.none;
+      } else if (licenseAccepted.hasMatch(line)) {
+        status ??= LicensesAccepted.all;
       }
     }
 
@@ -235,19 +248,14 @@ class AndroidLicenseValidator extends DoctorValidator {
     final Future<void> output = process.stdout
       .transform<String>(const Utf8Decoder(allowMalformed: true))
       .transform<String>(const LineSplitter())
-      .listen(_onLine)
+      .listen(_handleLine)
       .asFuture<void>(null);
     final Future<void> errors = process.stderr
       .transform<String>(const Utf8Decoder(allowMalformed: true))
       .transform<String>(const LineSplitter())
-      .listen(_onLine)
+      .listen(_handleLine)
       .asFuture<void>(null);
-    try {
-      await Future.wait<void>(<Future<void>>[output, errors]).timeout(const Duration(seconds: 30));
-    } catch (TimeoutException) {
-      printTrace(userMessages.androidLicensesTimeout(androidSdk.sdkManagerPath));
-      processManager.killPid(process.pid);
-    }
+    await Future.wait<void>(<Future<void>>[output, errors]);
     return status ?? LicensesAccepted.unknown;
   }
 
@@ -261,9 +269,10 @@ class AndroidLicenseValidator extends DoctorValidator {
     _ensureCanRunSdkManager();
 
     final Version sdkManagerVersion = Version.parse(androidSdk.sdkManagerVersion);
-    if (sdkManagerVersion == null || sdkManagerVersion.major < 26)
+    if (sdkManagerVersion == null || sdkManagerVersion.major < 26) {
       // SDK manager is found, but needs to be updated.
       throwToolExit(userMessages.androidSdkOutdated(androidSdk.sdkManagerPath));
+    }
 
     final Process process = await runCommand(
       <String>[androidSdk.sdkManagerPath, '--licenses'],

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

@@ -97,7 +97,7 @@ Future<GradleProject> _readGradleProject() async {
   final FlutterProject flutterProject = await FlutterProject.current();
   final String gradle = await _ensureGradle(flutterProject);
   updateLocalProperties(project: flutterProject);
-  final Status status = logger.startProgress('Resolving dependencies...', expectSlowOperation: true);
+  final Status status = logger.startProgress('Resolving dependencies...', timeout: kSlowOperation);
   GradleProject project;
   try {
     final RunResult propertiesRunResult = await runCheckedAsync(
@@ -174,7 +174,7 @@ Future<String> _ensureGradle(FlutterProject project) async {
 // of validating the Gradle executable. This may take several seconds.
 Future<String> _initializeGradle(FlutterProject project) async {
   final Directory android = project.android.hostAppGradleRoot;
-  final Status status = logger.startProgress('Initializing gradle...', expectSlowOperation: true);
+  final Status status = logger.startProgress('Initializing gradle...', timeout: kSlowOperation);
   String gradle = _locateGradlewExecutable(android);
   if (gradle == null) {
     injectGradleWrapper(android);
@@ -312,8 +312,8 @@ Future<void> buildGradleProject({
 Future<void> _buildGradleProjectV1(FlutterProject project, String gradle) async {
   // Run 'gradlew build'.
   final Status status = logger.startProgress(
-    "Running 'gradlew build'...",
-    expectSlowOperation: true,
+    'Running \'gradlew build\'...',
+    timeout: kSlowOperation,
     multilineOutput: true,
   );
   final int exitCode = await runCommandAndStreamOutput(
@@ -354,8 +354,8 @@ Future<void> _buildGradleProjectV2(
     }
   }
   final Status status = logger.startProgress(
-    "Gradle task '$assembleTask'...",
-    expectSlowOperation: true,
+    'Running Gradle task \'$assembleTask\'...',
+    timeout: kSlowOperation,
     multilineOutput: true,
   );
   final String gradlePath = fs.file(gradle).absolute.path;

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

@@ -107,7 +107,7 @@ class AppContext {
 
   /// Gets the value associated with the specified [type], or `null` if no
   /// such value has been associated.
-  dynamic operator [](Type type) {
+  Object operator [](Type type) {
     dynamic value = _generateIfNecessary(type, _overrides);
     if (value == null && _parent != null)
       value = _parent[type];

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

@@ -36,9 +36,7 @@ RecordingFileSystem getRecordingFileSystem(String location) {
   final RecordingFileSystem fileSystem = RecordingFileSystem(
       delegate: _kLocalFs, destination: dir);
   addShutdownHook(() async {
-    await fileSystem.recording.flush(
-      pendingResultTimeout: const Duration(seconds: 5),
-    );
+    await fileSystem.recording.flush();
   }, ShutdownStage.SERIALIZE_RECORDING);
   return fileSystem;
 }

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

@@ -162,10 +162,7 @@ class Stdio {
   bool get supportsAnsiEscapes => hasTerminal ? io.stdout.supportsAnsiEscapes : false;
 }
 
-io.IOSink get stderr => context[Stdio].stderr;
-
-Stream<List<int>> get stdin => context[Stdio].stdin;
-
-io.IOSink get stdout => context[Stdio].stdout;
-
 Stdio get stdio => context[Stdio];
+io.IOSink get stdout => stdio.stdout;
+Stream<List<int>> get stdin => stdio.stdin;
+io.IOSink get stderr => stdio.stderr;

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

@@ -37,7 +37,7 @@ Future<List<int>> _attempt(Uri url, {bool onlyHeaders = false}) async {
   printTrace('Downloading: $url');
   HttpClient httpClient;
   if (context[HttpClientFactory] != null) {
-    httpClient = context[HttpClientFactory]();
+    httpClient = (context[HttpClientFactory] as HttpClientFactory)(); // ignore: avoid_as
   } else {
     httpClient = HttpClient();
   }

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

@@ -203,14 +203,6 @@ Future<int> runInteractively(List<String> command, {
   return await process.exitCode;
 }
 
-Future<void> runAndKill(List<String> cmd, Duration timeout) {
-  final Future<Process> proc = runDetached(cmd);
-  return Future<void>.delayed(timeout, () async {
-    printTrace('Intentionally killing ${cmd[0]}');
-    processManager.killPid((await proc).pid);
-  });
-}
-
 Future<Process> runDetached(List<String> cmd) {
   _traceCommand(cmd);
   final Future<Process> proc = processManager.start(

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

@@ -5,8 +5,6 @@
 import 'dart:async';
 import 'dart:convert' show AsciiDecoder;
 
-import 'package:quiver/strings.dart';
-
 import '../globals.dart';
 import 'context.dart';
 import 'io.dart' as io;
@@ -172,31 +170,32 @@ class AnsiTerminal {
   /// Return keystrokes from the console.
   ///
   /// Useful when the console is in [singleCharMode].
-  Stream<String> get onCharInput {
+  Stream<String> get keystrokes {
     _broadcastStdInString ??= io.stdin.transform<String>(const AsciiDecoder(allowInvalid: true)).asBroadcastStream();
     return _broadcastStdInString;
   }
 
-  /// Prompts the user to input a character within the accepted list. Re-prompts
-  /// if entered character is not in the list.
+  /// Prompts the user to input a character within a given list. Re-prompts if
+  /// entered character is not in the list.
   ///
-  /// The [prompt] is the text displayed prior to waiting for user input. The
-  /// [defaultChoiceIndex], if given, will be the character appearing in
-  /// [acceptedCharacters] in the index given if the user presses enter without
-  /// any key input. Setting [displayAcceptedCharacters] also prints the
-  /// accepted keys next to the [prompt].
+  /// The `prompt`, if non-null, is the text displayed prior to waiting for user
+  /// input each time. If `prompt` is non-null and `displayAcceptedCharacters`
+  /// is true, the accepted keys are printed next to the `prompt`.
   ///
-  /// Throws a [TimeoutException] if a `timeout` is provided and its duration
-  /// expired without user input. Duration resets per key press.
+  /// The returned value is the user's input; if `defaultChoiceIndex` is not
+  /// null, and the user presses enter without any other input, the return value
+  /// will be the character in `acceptedCharacters` at the index given by
+  /// `defaultChoiceIndex`.
   Future<String> promptForCharInput(
     List<String> acceptedCharacters, {
     String prompt,
     int defaultChoiceIndex,
     bool displayAcceptedCharacters = true,
-    Duration timeout,
   }) async {
     assert(acceptedCharacters != null);
     assert(acceptedCharacters.isNotEmpty);
+    assert(prompt == null || prompt.isNotEmpty);
+    assert(displayAcceptedCharacters != null);
     List<String> charactersToDisplay = acceptedCharacters;
     if (defaultChoiceIndex != null) {
       assert(defaultChoiceIndex >= 0 && defaultChoiceIndex < acceptedCharacters.length);
@@ -206,17 +205,14 @@ class AnsiTerminal {
     }
     String choice;
     singleCharMode = true;
-    while (isEmpty(choice) || choice.length != 1 || !acceptedCharacters.contains(choice)) {
-      if (isNotEmpty(prompt)) {
+    while (choice == null || choice.length > 1 || !acceptedCharacters.contains(choice)) {
+      if (prompt != null) {
         printStatus(prompt, emphasis: true, newline: false);
         if (displayAcceptedCharacters)
           printStatus(' [${charactersToDisplay.join("|")}]', newline: false);
         printStatus(': ', emphasis: true, newline: false);
       }
-      Future<String> inputFuture = onCharInput.first;
-      if (timeout != null)
-        inputFuture = inputFuture.timeout(timeout);
-      choice = await inputFuture;
+      choice = await keystrokes.first;
       printStatus(choice);
     }
     singleCharMode = false;

packages/flutter_tools/lib/src/cache.dart

@@ -299,7 +299,7 @@ abstract class CachedArtifact {
   Future<void> _downloadArchive(String message, Uri url, Directory location, bool verifier(File f), void extractor(File f, Directory d)) {
     return _withDownloadFile('${flattenNameSubdirs(url)}', (File tempFile) async {
       if (!verifier(tempFile)) {
-        final Status status = logger.startProgress(message, expectSlowOperation: true);
+        final Status status = logger.startProgress(message, timeout: kSlowOperation);
         try {
           await _downloadFile(url, tempFile);
           status.stop();
@@ -620,7 +620,7 @@ Future<void> _downloadFile(Uri url, File location) async {
 }
 
 Future<bool> _doesRemoteExist(String message, Uri url) async {
-  final Status status = logger.startProgress(message, expectSlowOperation: true);
+  final Status status = logger.startProgress(message, timeout: kSlowOperation);
   final bool exists = await doesRemoteFileExist(url);
   status.stop();
   return exists;

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

@@ -74,11 +74,12 @@ class AnalyzeContinuously extends AnalyzeBase {
       analysisStatus?.cancel();
       if (!firstAnalysis)
         printStatus('\n');
-      analysisStatus = logger.startProgress('Analyzing $analysisTarget...');
+      analysisStatus = logger.startProgress('Analyzing $analysisTarget...', timeout: kSlowOperation);
       analyzedPaths.clear();
       analysisTimer = Stopwatch()..start();
     } else {
       analysisStatus?.stop();
+      analysisStatus = null;
       analysisTimer.stop();
 
       logger.printStatus(terminal.clearScreen(), newline: false);

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

@@ -107,7 +107,7 @@ class AnalyzeOnce extends AnalyzeBase {
         ? '${directories.length} ${directories.length == 1 ? 'directory' : 'directories'}'
         : fs.path.basename(directories.first);
     final Status progress = argResults['preamble']
-        ? logger.startProgress('Analyzing $message...')
+        ? logger.startProgress('Analyzing $message...', timeout: kSlowOperation)
         : null;
 
     await analysisCompleter.future;

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

@@ -149,7 +149,7 @@ class AttachCommand extends FlutterCommand {
         }
         final Status status = logger.startProgress(
           'Waiting for a connection from Flutter on ${device.name}...',
-          expectSlowOperation: true,
+          timeout: kSlowOperation,
         );
         try {
           final int localPort = await device.findIsolatePort(module, localPorts);
@@ -179,7 +179,7 @@ class AttachCommand extends FlutterCommand {
           observatoryUri = await observatoryDiscovery.uri;
           // Determine ipv6 status from the scanned logs.
           usesIpv6 = observatoryDiscovery.ipv6;
-          printStatus('Done.');
+          printStatus('Done.'); // FYI, this message is used as a sentinel in tests.
         } finally {
           await observatoryDiscovery?.cancel();
         }
@@ -217,20 +217,29 @@ class AttachCommand extends FlutterCommand {
         flutterDevice.startEchoingDeviceLog();
       }
 
+      int result;
       if (daemon != null) {
         AppInstance app;
         try {
-          app = await daemon.appDomain.launch(hotRunner, hotRunner.attach,
-              device, null, true, fs.currentDirectory);
+          app = await daemon.appDomain.launch(
+            hotRunner,
+            hotRunner.attach,
+            device,
+            null,
+            true,
+            fs.currentDirectory,
+          );
         } catch (error) {
           throwToolExit(error.toString());
         }
-        final int result = await app.runner.waitForAppToFinish();
-        if (result != 0)
-          throwToolExit(null, exitCode: result);
+        result = await app.runner.waitForAppToFinish();
+        assert(result != null);
       } else {
-        await hotRunner.attach();
+        result = await hotRunner.attach();
+        assert(result != null);
       }
+      if (result != 0)
+        throwToolExit(null, exitCode: result);
     } finally {
       final List<ForwardedPort> ports = device.portForwarder.forwardedPorts.toList();
       for (ForwardedPort port in ports) {

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

@@ -71,7 +71,7 @@ class BuildAotCommand extends BuildSubCommand {
       final String typeName = artifacts.getEngineType(platform, buildMode);
       status = logger.startProgress(
         'Building AOT snapshot in ${getModeName(getBuildMode())} mode ($typeName)...',
-        expectSlowOperation: true,
+        timeout: kSlowOperation,
       );
     }
     final String outputPath = argResults['output-dir'] ?? getAotBuildDirectory();

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

@@ -428,9 +428,10 @@ class AppDomain extends Domain {
       });
     }
     final Completer<void> appStartedCompleter = Completer<void>();
-    // We don't want to wait for this future to complete and callbacks won't fail.
-    // As it just writes to stdout.
-    appStartedCompleter.future.then<void>((_) { // ignore: unawaited_futures
+    // We don't want to wait for this future to complete and callbacks won't fail,
+    // as it just writes to stdout.
+    appStartedCompleter.future // ignore: unawaited_futures
+      .then<void>((void value) {
         _sendAppEvent(app, 'started');
       });
 
@@ -515,14 +516,15 @@ class AppDomain extends Domain {
     if (app == null)
       throw "app '$appId' not found";
 
-    return app.stop().timeout(const Duration(seconds: 5)).then<bool>((_) {
-      return true;
-    }).catchError((dynamic error) {
+    return app.stop().then<bool>(
+      (void value) => true,
+      onError: (dynamic error, StackTrace stack) {
         _sendAppEvent(app, 'log', <String, dynamic>{ 'log': '$error', 'error': true });
         app.closeLogger();
         _apps.remove(app);
         return false;
-    });
+      },
+    );
   }
 
   Future<bool> detach(Map<String, dynamic> args) async {
@@ -532,14 +534,15 @@ class AppDomain extends Domain {
     if (app == null)
       throw "app '$appId' not found";
 
-    return app.detach().timeout(const Duration(seconds: 5)).then<bool>((_) {
-      return true;
-    }).catchError((dynamic error) {
+    return app.detach().then<bool>(
+      (void value) => true,
+      onError: (dynamic error, StackTrace stack) {
         _sendAppEvent(app, 'log', <String, dynamic>{ 'log': '$error', 'error': true });
         app.closeLogger();
         _apps.remove(app);
         return false;
-    });
+      },
+    );
   }
 
   AppInstance _getApp(String id) {
@@ -772,13 +775,14 @@ class NotifyingLogger extends Logger {
   @override
   Status startProgress(
     String message, {
+    @required Duration timeout,
     String progressId,
-    bool expectSlowOperation = false,
     bool multilineOutput,
     int progressIndicatorPadding = kDefaultStatusPadding,
   }) {
+    assert(timeout != null);
     printStatus(message);
-    return Status();
+    return SilentStatus(timeout: timeout);
   }
 
   void dispose() {
@@ -948,11 +952,12 @@ class _AppRunLogger extends Logger {
   @override
   Status startProgress(
     String message, {
+    @required Duration timeout,
     String progressId,
-    bool expectSlowOperation = false,
     bool multilineOutput,
     int progressIndicatorPadding = 52,
   }) {
+    assert(timeout != null);
     final int id = _nextProgressId++;
 
     _sendProgressEvent(<String, dynamic>{
@@ -961,13 +966,16 @@ class _AppRunLogger extends Logger {
       'message': message,
     });
 
-    _status = Status(onFinish: () {
+    _status = SilentStatus(
+      timeout: timeout,
+      onFinish: () {
         _status = null;
         _sendProgressEvent(<String, dynamic>{
           'id': id.toString(),
           'progressId': progressId,
-        'finished': true
-      });
+          'finished': true,
+        },
+      );
     })..start();
     return _status;
   }

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

@@ -29,11 +29,11 @@ class LogsCommand extends FlutterCommand {
   Device device;
 
   @override
-  Future<FlutterCommandResult> verifyThenRunCommand() async {
+  Future<FlutterCommandResult> verifyThenRunCommand(String commandPath) async {
     device = await findTargetDevice();
     if (device == null)
       throwToolExit(null);
-    return super.verifyThenRunCommand();
+    return super.verifyThenRunCommand(commandPath);
   }
 
   @override

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

@@ -64,7 +64,7 @@ class ScreenshotCommand extends FlutterCommand {
   Device device;
 
   @override
-  Future<FlutterCommandResult> verifyThenRunCommand() async {
+  Future<FlutterCommandResult> verifyThenRunCommand(String commandPath) async {
     device = await findTargetDevice();
     if (device == null)
       throwToolExit('Must have a connected device');
@@ -72,7 +72,7 @@ class ScreenshotCommand extends FlutterCommand {
       throwToolExit('Screenshot not supported for ${device.name}.');
     if (argResults[_kType] != _kDeviceType && argResults[_kObservatoryPort] == null)
       throwToolExit('Observatory port must be specified for screenshot type ${argResults[_kType]}');
-    return super.verifyThenRunCommand();
+    return super.verifyThenRunCommand(commandPath);
   }
 
   @override

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

@@ -95,7 +95,7 @@ class UpdatePackagesCommand extends FlutterCommand {
   Future<void> _downloadCoverageData() async {
     final Status status = logger.startProgress(
       'Downloading lcov data for package:flutter...',
-      expectSlowOperation: true,
+      timeout: kSlowOperation,
     );
     final String urlBase = platform.environment['FLUTTER_STORAGE_BASE_URL'] ?? 'https://storage.googleapis.com';
     final List<int> data = await fetchUrl(Uri.parse('$urlBase/flutter_infra/flutter/coverage/lcov.info'));

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

@@ -92,7 +92,7 @@ Future<void> pubGet({
     final String command = upgrade ? 'upgrade' : 'get';
     final Status status = logger.startProgress(
       'Running "flutter packages $command" in ${fs.path.basename(directory)}...',
-      expectSlowOperation: true,
+      timeout: kSlowOperation,
     );
     final List<String> args = <String>['--verbosity=warning'];
     if (FlutterCommand.current != null && FlutterCommand.current.globalResults['verbose'])

packages/flutter_tools/lib/src/device.dart

@@ -150,7 +150,7 @@ abstract class PollingDeviceDiscovery extends DeviceDiscovery {
           final List<Device> devices = await pollingGetDevices().timeout(_pollingTimeout);
           _items.updateWithNewList(devices);
         } on TimeoutException {
-          printTrace('Device poll timed out.');
+          printTrace('Device poll timed out. Will retry.');
         }
       }, _pollingInterval);
     }

packages/flutter_tools/lib/src/doctor.dart

@@ -184,7 +184,10 @@ class Doctor {
 
     for (ValidatorTask validatorTask in startValidatorTasks()) {
       final DoctorValidator validator = validatorTask.validator;
-      final Status status = Status.withSpinner();
+      final Status status = Status.withSpinner(
+        timeout: kFastOperation,
+        slowWarningCallback: () => validator.slowWarning,
+      );
       ValidationResult result;
       try {
         result = await validatorTask.result;
@@ -286,6 +289,8 @@ abstract class DoctorValidator {
 
   final String title;
 
+  String get slowWarning => 'This is taking an unexpectedly long time...';
+
   Future<ValidationResult> validate();
 }
 
@@ -298,6 +303,10 @@ class GroupedValidator extends DoctorValidator {
 
   final List<DoctorValidator> subValidators;
 
+  @override
+  String get slowWarning => _currentSlowWarning;
+  String _currentSlowWarning = 'Initializing...';
+
   @override
   Future<ValidationResult> validate() async  {
     final List<ValidatorTask> tasks = <ValidatorTask>[];
@@ -307,8 +316,10 @@ class GroupedValidator extends DoctorValidator {
 
     final List<ValidationResult> results = <ValidationResult>[];
     for (ValidatorTask subValidator in tasks) {
+      _currentSlowWarning = subValidator.validator.slowWarning;
       results.add(await subValidator.result);
     }
+    _currentSlowWarning = 'Merging results...';
     return _mergeValidationResults(results);
   }
 
@@ -671,6 +682,9 @@ class IntelliJValidatorOnMac extends IntelliJValidator {
 class DeviceValidator extends DoctorValidator {
   DeviceValidator() : super('Connected device');
 
+  @override
+  String get slowWarning => 'Scanning for devices is taking a long time...';
+
   @override
   Future<ValidationResult> validate() async {
     final List<Device> devices = await deviceManager.getAllConnectedDevices().toList();

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

@@ -220,7 +220,7 @@ class CocoaPods {
   }
 
   Future<void> _runPodInstall(IosProject iosProject, String engineDirectory) async {
-    final Status status = logger.startProgress('Running pod install...', expectSlowOperation: true);
+    final Status status = logger.startProgress('Running pod install...', timeout: kSlowOperation);
     final ProcessResult result = await processManager.run(
       <String>['pod', 'install', '--verbose'],
       workingDirectory: iosProject.hostAppRoot.path,

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

@@ -26,8 +26,6 @@ const String _kIdeviceinstallerInstructions =
     'To work with iOS devices, please install ideviceinstaller. To install, run:\n'
     'brew install ideviceinstaller.';
 
-const Duration kPortForwardTimeout = Duration(seconds: 10);
-
 class IOSDeploy {
   const IOSDeploy();
 
@@ -297,7 +295,7 @@ class IOSDevice extends Device {
     int installationResult = -1;
     Uri localObservatoryUri;
 
-    final Status installStatus = logger.startProgress('Installing and launching...', expectSlowOperation: true);
+    final Status installStatus = logger.startProgress('Installing and launching...', timeout: kSlowOperation);
 
     if (!debuggingOptions.debuggingEnabled) {
       // If debugging is not enabled, just launch the application and continue.

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

@@ -470,7 +470,7 @@ Future<XcodeBuildResult> buildXcodeProject({
           initialBuildStatus.cancel();
           buildSubStatus = logger.startProgress(
             line,
-            expectSlowOperation: true,
+            timeout: kSlowOperation,
             progressIndicatorPadding: kDefaultStatusPadding - 7,
           );
         }
@@ -485,7 +485,7 @@ Future<XcodeBuildResult> buildXcodeProject({
   }
 
   final Stopwatch buildStopwatch = Stopwatch()..start();
-  initialBuildStatus = logger.startProgress('Starting Xcode build...');
+  initialBuildStatus = logger.startProgress('Starting Xcode build...', timeout: kFastOperation);
   final RunResult buildResult = await runAsync(
     buildCommands,
     workingDirectory: app.project.hostAppRoot.path,

packages/flutter_tools/lib/src/resident_runner.dart

@@ -9,7 +9,6 @@ import 'package:meta/meta.dart';
 import 'application_package.dart';
 import 'artifacts.dart';
 import 'asset.dart';
-import 'base/common.dart';
 import 'base/file_system.dart';
 import 'base/io.dart';
 import 'base/logger.dart';
@@ -72,11 +71,13 @@ class FlutterDevice {
     if (vmServices != null)
       return;
     final List<VMService> localVmServices = List<VMService>(observatoryUris.length);
-    for (int i = 0; i < observatoryUris.length; i++) {
+    for (int i = 0; i < observatoryUris.length; i += 1) {
       printTrace('Connecting to service protocol: ${observatoryUris[i]}');
-      localVmServices[i] = await VMService.connect(observatoryUris[i],
+      localVmServices[i] = await VMService.connect(
+        observatoryUris[i],
         reloadSources: reloadSources,
-          compileExpression: compileExpression);
+        compileExpression: compileExpression,
+      );
       printTrace('Successfully connected to service protocol: ${observatoryUris[i]}');
     }
     vmServices = localVmServices;
@@ -112,13 +113,16 @@ class FlutterDevice {
     final List<FlutterView> flutterViews = views;
     if (flutterViews == null || flutterViews.isEmpty)
       return;
+    final List<Future<void>> futures = <Future<void>>[];
     for (FlutterView view in flutterViews) {
       if (view != null && view.uiIsolate != null) {
-        // Manage waits specifically below.
-        view.uiIsolate.flutterExit(); // ignore: unawaited_futures
+        futures.add(view.uiIsolate.flutterExit());
       }
     }
-    await Future<void>.delayed(const Duration(milliseconds: 100));
+    // The flutterExit message only returns if it fails, so just wait a few
+    // seconds then assume it worked.
+    // TODO(ianh): We should make this return once the VM service disconnects.
+    await Future.wait(futures).timeout(const Duration(seconds: 2), onTimeout: () { });
   }
 
   Future<Uri> setupDevFS(String fsName,
@@ -382,7 +386,7 @@ class FlutterDevice {
   }) async {
     final Status devFSStatus = logger.startProgress(
       'Syncing files to device ${device.name}...',
-      expectSlowOperation: true,
+      timeout: kFastOperation,
     );
     int bytes = 0;
     try {
@@ -474,11 +478,14 @@ abstract class ResidentRunner {
   }
 
   /// Start the app and keep the process running during its lifetime.
+  ///
+  /// Returns the exit code that we should use for the flutter tool process; 0
+  /// for success, 1 for user error (e.g. bad arguments), 2 for other failures.
   Future<int> run({
     Completer<DebugConnectionInfo> connectionInfoCompleter,
     Completer<void> appStartedCompleter,
     String route,
-    bool shouldBuild = true
+    bool shouldBuild = true,
   });
 
   bool get supportsRestart => false;
@@ -493,7 +500,7 @@ abstract class ResidentRunner {
       await _debugSaveCompilationTrace();
     await stopEchoingDeviceLog();
     await preStop();
-    return stopApp();
+    await stopApp();
   }
 
   Future<void> detach() async {
@@ -558,7 +565,7 @@ abstract class ResidentRunner {
   }
 
   Future<void> _screenshot(FlutterDevice device) async {
-    final Status status = logger.startProgress('Taking screenshot for ${device.device.name}...');
+    final Status status = logger.startProgress('Taking screenshot for ${device.device.name}...', timeout: kFastOperation);
     final File outputFile = getUniqueFile(fs.currentDirectory, 'flutter', 'png');
     try {
       if (supportsServiceProtocol && isRunningDebug) {
@@ -673,24 +680,32 @@ abstract class ResidentRunner {
   }
 
   /// If the [reloadSources] parameter is not null the 'reloadSources' service
-  /// will be registered
+  /// will be registered.
+  //
+  // Failures should be indicated by completing the future with an error, using
+  // a string as the error object, which will be used by the caller (attach())
+  // to display an error message.
   Future<void> connectToServiceProtocol({ReloadSources reloadSources, CompileExpression compileExpression}) async {
     if (!debuggingOptions.debuggingEnabled)
-      return Future<void>.error('Error the service protocol is not enabled.');
+      throw 'The service protocol is not enabled.';
 
     bool viewFound = false;
     for (FlutterDevice device in flutterDevices) {
-      await device._connect(reloadSources: reloadSources,
-          compileExpression: compileExpression);
+      await device._connect(
+        reloadSources: reloadSources,
+        compileExpression: compileExpression,
+      );
       await device.getVMs();
       await device.refreshViews();
-      if (device.views.isEmpty)
-        printStatus('No Flutter views available on ${device.device.name}');
-      else
+      if (device.views.isNotEmpty)
         viewFound = true;
     }
-    if (!viewFound)
-      throwToolExit('No Flutter view is available');
+    if (!viewFound) {
+      if (flutterDevices.length == 1)
+        throw 'No Flutter view is available on ${flutterDevices.first.device.name}.';
+      throw 'No Flutter view is available on any device '
+            '(${flutterDevices.map<String>((FlutterDevice device) => device.device.name).join(', ')}).';
+    }
 
     // Listen for service protocol connection to close.
     for (FlutterDevice device in flutterDevices) {
@@ -841,12 +856,13 @@ abstract class ResidentRunner {
         printHelp(details: false);
       }
       terminal.singleCharMode = true;
-      terminal.onCharInput.listen(processTerminalInput);
+      terminal.keystrokes.listen(processTerminalInput);
     }
   }
 
   Future<int> waitForAppToFinish() async {
     final int exitCode = await _finished.future;
+    assert(exitCode != null);
     await cleanupAtFinish();
     return exitCode;
   }
@@ -867,8 +883,10 @@ abstract class ResidentRunner {
   Future<void> preStop() async { }
 
   Future<void> stopApp() async {
+    final List<Future<void>> futures = <Future<void>>[];
     for (FlutterDevice device in flutterDevices)
-      await device.stopApps();
+      futures.add(device.stopApps());
+    await Future.wait(futures);
     appFinished();
   }
 

packages/flutter_tools/lib/src/run_cold.dart

@@ -64,8 +64,14 @@ class ColdRunner extends ResidentRunner {
     }
 
     // Connect to observatory.
-    if (debuggingOptions.debuggingEnabled)
+    if (debuggingOptions.debuggingEnabled) {
+      try {
         await connectToServiceProtocol();
+      } on String catch (message) {
+        printError(message);
+        return 2;
+      }
+    }
 
     if (flutterDevices.first.observatoryUris != null) {
       // For now, only support one debugger connection.

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

@@ -454,19 +454,17 @@ abstract class FlutterCommand extends Command<void> {
       body: () async {
         if (flutterUsage.isFirstRun)
           flutterUsage.printWelcome();
-
+        final String commandPath = await usagePath;
         FlutterCommandResult commandResult;
         try {
-          commandResult = await verifyThenRunCommand();
+          commandResult = await verifyThenRunCommand(commandPath);
         } on ToolExit {
           commandResult = const FlutterCommandResult(ExitStatus.fail);
           rethrow;
         } finally {
           final DateTime endTime = systemClock.now();
           printTrace('"flutter $name" took ${getElapsedAsMilliseconds(endTime.difference(startTime))}.');
-          // This is checking the result of the call to 'usagePath'
-          // (a Future<String>), and not the result of evaluating the Future.
-          if (usagePath != null) {
+          if (commandPath != null) {
             final List<String> labels = <String>[];
             if (commandResult?.exitStatus != null)
               labels.add(getEnumName(commandResult.exitStatus));
@@ -500,7 +498,7 @@ abstract class FlutterCommand extends Command<void> {
   /// then call this method to execute the command
   /// rather than calling [runCommand] directly.
   @mustCallSuper
-  Future<FlutterCommandResult> verifyThenRunCommand() async {
+  Future<FlutterCommandResult> verifyThenRunCommand(String commandPath) async {
     await validateCommand();
 
     // Populate the cache. We call this before pub get below so that the sky_engine
@@ -516,8 +514,6 @@ abstract class FlutterCommand extends Command<void> {
 
     setupApplicationPackages();
 
-    final String commandPath = await usagePath;
-
     if (commandPath != null) {
       final Map<String, String> additionalUsageValues = await usageValues;
       flutterUsage.sendCommand(commandPath, parameters: additionalUsageValues);

packages/flutter_tools/lib/src/test/coverage_collector.dart

@@ -57,13 +57,7 @@ class CoverageCollector extends TestWatcher {
         if (result == null)
           throw Exception('Failed to collect coverage.');
         data = result;
-      })
-      .timeout(
-        const Duration(minutes: 10),
-        onTimeout: () {
-          throw Exception('Timed out while collecting coverage.');
-        },
-      );
+      });
     await Future.any<void>(<Future<void>>[ processComplete, collectionComplete ]);
     assert(data != null);
 
@@ -77,12 +71,8 @@ class CoverageCollector extends TestWatcher {
   ///
   /// This will not start any collection tasks. It us up to the caller of to
   /// call [collectCoverage] for each process first.
-  ///
-  /// If [timeout] is specified, the future will timeout (with a
-  /// [TimeoutException]) after the specified duration.
   Future<String> finalizeCoverage({
     coverage.Formatter formatter,
-    Duration timeout,
     Directory coverageDirectory,
   }) async {
     printTrace('formating coverage data');
@@ -102,9 +92,8 @@ class CoverageCollector extends TestWatcher {
   }
 
   Future<bool> collectCoverageData(String coveragePath, { bool mergeCoverageData = false, Directory coverageDirectory }) async {
-    final Status status = logger.startProgress('Collecting coverage information...');
+    final Status status = logger.startProgress('Collecting coverage information...', timeout: kFastOperation);
     final String coverageData = await finalizeCoverage(
-      timeout: const Duration(seconds: 30),
       coverageDirectory: coverageDirectory,
     );
     status.stop();

packages/flutter_tools/lib/src/test/flutter_platform.dart

@@ -33,11 +33,17 @@ import 'watcher.dart';
 
 /// The timeout we give the test process to connect to the test harness
 /// once the process has entered its main method.
+///
+/// We time out test execution because we expect some tests to hang and we want
+/// to know which test hung, rather than have the entire test harness just do
+/// nothing for a few hours until the user (or CI environment) gets bored.
 const Duration _kTestStartupTimeout = Duration(minutes: 1);
 
 /// The timeout we give the test process to start executing Dart code. When the
 /// CPU is under severe load, this can take a while, but it's not indicative of
 /// any problem with Flutter, so we give it a large timeout.
+///
+/// See comment under [_kTestStartupTimeout] regarding timeouts.
 const Duration _kTestProcessTimeout = Duration(minutes: 5);
 
 /// Message logged by the test process to signal that its main method has begun
@@ -288,12 +294,10 @@ class _Compiler {
             firstCompile = true;
           }
           suppressOutput = false;
-          final CompilerOutput compilerOutput = await handleTimeout<CompilerOutput>(
-            compiler.recompile(
+          final CompilerOutput compilerOutput = await compiler.recompile(
             request.path,
             <String>[request.path],
-              outputPath: outputDill.path),
-              request.path,
+            outputPath: outputDill.path,
           );
           final String outputPath = compilerOutput?.outputFilename;
 
@@ -337,7 +341,7 @@ class _Compiler {
   Future<String> compile(String mainDart) {
     final Completer<String> completer = Completer<String>();
     compilerController.add(_CompilationRequest(mainDart, completer));
-    return handleTimeout<String>(completer.future, mainDart);
+    return completer.future;
   }
 
   Future<void> _shutdown() async {
@@ -353,13 +357,6 @@ class _Compiler {
     await _shutdown();
     await compilerController.close();
   }
-
-  static Future<T> handleTimeout<T>(Future<T> value, String path) {
-    return value.timeout(const Duration(minutes: 5), onTimeout: () {
-      printError('Compilation of $path timed out after 5 minutes.');
-      return null;
-    });
-  }
 }
 
 class _FlutterPlatform extends PlatformPlugin {

packages/flutter_tools/lib/src/tracing.dart

@@ -35,14 +35,12 @@ class Tracing {
     bool waitForFirstFrame = false
   }) async {
     Map<String, dynamic> timeline;
-
     if (!waitForFirstFrame) {
       // Stop tracing immediately and get the timeline
       await vmService.vm.setVMTimelineFlags(<String>[]);
       timeline = await vmService.vm.getVMTimeline();
     } else {
       final Completer<void> whenFirstFrameRendered = Completer<void>();
-
       (await vmService.onTimelineEvent).listen((ServiceEvent timelineEvent) {
         final List<Map<String, dynamic>> events = timelineEvent.timelineEvents;
         for (Map<String, dynamic> event in events) {
@@ -50,24 +48,10 @@ class Tracing {
             whenFirstFrameRendered.complete();
         }
       });
-
-      await whenFirstFrameRendered.future.timeout(
-          const Duration(seconds: 10),
-          onTimeout: () {
-            printError(
-                'Timed out waiting for the first frame event. Either the '
-                    'application failed to start, or the event was missed because '
-                    '"flutter run" took too long to subscribe to timeline events.'
-            );
-            return null;
-          }
-      );
-
+      await whenFirstFrameRendered.future;
       timeline = await vmService.vm.getVMTimeline();
-
       await vmService.vm.setVMTimelineFlags(<String>[]);
     }
-
     return timeline;
   }
 }

packages/flutter_tools/lib/src/vscode/vscode_validator.dart

@@ -14,7 +14,6 @@ class VsCodeValidator extends DoctorValidator {
 
   final VsCode _vsCode;
 
-
   static Iterable<DoctorValidator> get installedValidators {
     return VsCode
         .allInstalled()

packages/flutter_tools/test/base/context_test.dart

@@ -158,7 +158,7 @@ void main() {
           fallbacks: <Type, Generator>{
             int: () => int.parse(context[String]),
             String: () => '${context[double]}',
-            double: () => context[int] * 1.0,
+            double: () => (context[int] as int) * 1.0, // ignore: avoid_as
           },
         );
         try {

packages/flutter_tools/test/base/terminal_test.dart

@@ -165,7 +165,7 @@ Stream<String> mockStdInStream;
 
 class TestTerminal extends AnsiTerminal {
   @override
-  Stream<String> get onCharInput {
+  Stream<String> get keystrokes {
     return mockStdInStream;
   }
 }

packages/flutter_tools/test/integration/daemon_mode_test.dart

@@ -90,5 +90,5 @@ void main() {
       expect(result, isList);
       expect(result, isNotEmpty);
     });
-  }, timeout: const Timeout.factor(2));
+  }, timeout: const Timeout.factor(10)); // This test uses the `flutter` tool, which could be blocked behind the startup lock for a long time.
 }

packages/flutter_tools/test/integration/debugger_stepping_test.dart

@@ -28,13 +28,15 @@ void main() {
     });
 
     test('can step over statements', () async {
-      await _flutter.run(withDebugger: true);
+      await _flutter.run(withDebugger: true, startPaused: true);
+      await _flutter.addBreakpoint(_project.breakpointUri, _project.breakpointLine);
+      await _flutter.resume();
+      await _flutter.waitForPause(); // Now we should be on the breakpoint.
 
-      // Stop at the initial breakpoint that the expected steps are based on.
-      await _flutter.breakAt(_project.breakpointUri, _project.breakpointLine, restart: true);
+      expect((await _flutter.getSourceLocation()).line, equals(_project.breakpointLine));
 
       // Issue 5 steps, ensuring that we end up on the annotated lines each time.
-      for (int i = 1; i <= _project.numberOfSteps; i++) {
+      for (int i = 1; i <= _project.numberOfSteps; i += 1) {
         await _flutter.stepOverOrOverAsyncSuspension();
         final SourcePosition location = await _flutter.getSourceLocation();
         final int actualLine = location.line;
@@ -47,5 +49,5 @@ void main() {
           reason: 'After $i steps, debugger should stop at $expectedLine but stopped at $actualLine');
       }
     });
-  }, timeout: const Timeout.factor(3));
+  }, timeout: const Timeout.factor(10)); // The DevFS sync takes a really long time, so these tests can be slow.
 }

packages/flutter_tools/test/integration/expression_evaluation_test.dart

@@ -31,16 +31,18 @@ void main() {
       tryToDelete(tempDir);
     });
 
-    Future<Isolate> breakInBuildMethod(FlutterTestDriver flutter) async {
-      return _flutter.breakAt(
+    Future<void> breakInBuildMethod(FlutterTestDriver flutter) async {
+      await _flutter.breakAt(
         _project.buildMethodBreakpointUri,
-          _project.buildMethodBreakpointLine);
+        _project.buildMethodBreakpointLine,
+      );
     }
 
-    Future<Isolate> breakInTopLevelFunction(FlutterTestDriver flutter) async {
-      return _flutter.breakAt(
+    Future<void> breakInTopLevelFunction(FlutterTestDriver flutter) async {
+      await _flutter.breakAt(
         _project.topLevelFunctionBreakpointUri,
-          _project.topLevelFunctionBreakpointLine);
+        _project.topLevelFunctionBreakpointLine,
+      );
     }
 
     test('can evaluate trivial expressions in top level function', () async {
@@ -78,7 +80,8 @@ void main() {
       await breakInBuildMethod(_flutter);
       await evaluateComplexReturningExpressions(_flutter);
     });
-  }, timeout: const Timeout.factor(6));
+
+  }, timeout: const Timeout.factor(10)); // The DevFS sync takes a really long time, so these tests can be slow.
 }
 
 Future<void> evaluateTrivialExpressions(FlutterTestDriver flutter) async {

packages/flutter_tools/test/integration/flutter_attach_test.dart

@@ -18,8 +18,8 @@ void main() {
   setUp(() async {
     tempDir = createResolvedTempDirectorySync();
     await _project.setUpIn(tempDir);
-    _flutterRun = FlutterRunTestDriver(tempDir, logPrefix: 'RUN');
-    _flutterAttach = FlutterRunTestDriver(tempDir, logPrefix: 'ATTACH');
+    _flutterRun = FlutterRunTestDriver(tempDir,    logPrefix: '   RUN  ');
+    _flutterAttach = FlutterRunTestDriver(tempDir, logPrefix: 'ATTACH  ');
   });
 
   tearDown(() async {
@@ -58,5 +58,5 @@ void main() {
       await _flutterAttach.attach(_flutterRun.vmServicePort);
       await _flutterAttach.hotReload();
     });
-  }, timeout: const Timeout.factor(6));
+  }, timeout: const Timeout.factor(10)); // The DevFS sync takes a really long time, so these tests can be slow.
 }

packages/flutter_tools/test/integration/flutter_run_test.dart

@@ -55,5 +55,5 @@ void main() {
       await _flutter.run(pidFile: pidFile);
       expect(pidFile.existsSync(), isTrue);
     });
-  }, timeout: const Timeout.factor(6));
+  }, timeout: const Timeout.factor(10)); // The DevFS sync takes a really long time, so these tests can be slow.
 }

packages/flutter_tools/test/integration/hot_reload_test.dart

@@ -14,7 +14,7 @@ import 'test_driver.dart';
 import 'test_utils.dart';
 
 void main() {
-  group('hot', () {
+  group('hot reload tests', () {
     Directory tempDir;
     final HotReloadProject _project = HotReloadProject();
     FlutterRunTestDriver _flutter;
@@ -26,39 +26,127 @@ void main() {
     });
 
     tearDown(() async {
-      await _flutter.stop();
+      await _flutter?.stop();
       tryToDelete(tempDir);
     });
 
-    test('reload works without error', () async {
+    test('hot reload works without error', () async {
       await _flutter.run();
       await _flutter.hotReload();
     });
 
-    test('newly added code executes during reload', () async {
+    test('newly added code executes during hot reload', () async {
       await _flutter.run();
       _project.uncommentHotReloadPrint();
       final StringBuffer stdout = StringBuffer();
-      final StreamSubscription<String> sub = _flutter.stdout.listen(stdout.writeln);
+      final StreamSubscription<String> subscription = _flutter.stdout.listen(stdout.writeln);
       try {
             await _flutter.hotReload();
             expect(stdout.toString(), contains('(((((RELOAD WORKED)))))'));
       } finally {
-        await sub.cancel();
+        await subscription.cancel();
       }
     });
 
-    test('restart works without error', () async {
+    test('hot restart works without error', () async {
       await _flutter.run();
       await _flutter.hotRestart();
     });
 
-    test('reload hits breakpoints after reload', () async {
+    test('breakpoints are hit after hot reload', () async {
+      Isolate isolate;
+      await _flutter.run(withDebugger: true, startPaused: true);
+      final Completer<void> sawTick1 = Completer<void>();
+      final Completer<void> sawTick3 = Completer<void>();
+      final Completer<void> sawDebuggerPausedMessage = Completer<void>();
+      final StreamSubscription<String> subscription = _flutter.stdout.listen(
+        (String line) {
+          if (line.contains('((((TICK 1))))')) {
+            expect(sawTick1.isCompleted, isFalse);
+            sawTick1.complete();
+          }
+          if (line.contains('((((TICK 3))))')) {
+            expect(sawTick3.isCompleted, isFalse);
+            sawTick3.complete();
+          }
+          if (line.contains('The application is paused in the debugger on a breakpoint.')) {
+            expect(sawDebuggerPausedMessage.isCompleted, isFalse);
+            sawDebuggerPausedMessage.complete();
+          }
+        },
+      );
+      await _flutter.resume(); // we start paused so we can set up our TICK 1 listener before the app starts
+      sawTick1.future.timeout( // ignore: unawaited_futures
+        const Duration(seconds: 5),
+        onTimeout: () { print('The test app is taking longer than expected to print its synchronization line...'); },
+      );
+      await sawTick1.future; // after this, app is in steady state
+      await _flutter.addBreakpoint(
+        _project.scheduledBreakpointUri,
+        _project.scheduledBreakpointLine,
+      );
+      await _flutter.hotReload(); // reload triggers code which eventually hits the breakpoint
+      isolate = await _flutter.waitForPause();
+      expect(isolate.pauseEvent.kind, equals(EventKind.kPauseBreakpoint));
+      await _flutter.resume();
+      await _flutter.addBreakpoint(
+        _project.buildBreakpointUri,
+        _project.buildBreakpointLine,
+      );
+      bool reloaded = false;
+      final Future<void> reloadFuture = _flutter.hotReload().then((void value) { reloaded = true; });
+      await sawTick3.future; // this should happen before it pauses
+      isolate = await _flutter.waitForPause();
+      expect(isolate.pauseEvent.kind, equals(EventKind.kPauseBreakpoint));
+      await sawDebuggerPausedMessage.future;
+      expect(reloaded, isFalse);
+      await _flutter.resume();
+      await reloadFuture;
+      expect(reloaded, isTrue);
+      reloaded = false;
+      await subscription.cancel();
+    });
+
+    test('hot reload doesn\'t reassemble if paused', () async {
       await _flutter.run(withDebugger: true);
-      final Isolate isolate = await _flutter.breakAt(
-          _project.breakpointUri,
-          _project.breakpointLine);
+      final Completer<void> sawTick2 = Completer<void>();
+      final Completer<void> sawTick3 = Completer<void>();
+      final Completer<void> sawDebuggerPausedMessage1 = Completer<void>();
+      final Completer<void> sawDebuggerPausedMessage2 = Completer<void>();
+      final StreamSubscription<String> subscription = _flutter.stdout.listen(
+        (String line) {
+          if (line.contains('((((TICK 2))))')) {
+            expect(sawTick2.isCompleted, isFalse);
+            sawTick2.complete();
+          }
+          if (line.contains('The application is paused in the debugger on a breakpoint.')) {
+            expect(sawDebuggerPausedMessage1.isCompleted, isFalse);
+            sawDebuggerPausedMessage1.complete();
+          }
+          if (line.contains('The application is paused in the debugger on a breakpoint; interface might not update.')) {
+            expect(sawDebuggerPausedMessage2.isCompleted, isFalse);
+            sawDebuggerPausedMessage2.complete();
+          }
+        },
+      );
+      await _flutter.addBreakpoint(
+        _project.buildBreakpointUri,
+        _project.buildBreakpointLine,
+      );
+      bool reloaded = false;
+      final Future<void> reloadFuture = _flutter.hotReload().then((void value) { reloaded = true; });
+      await sawTick2.future; // this should happen before it pauses
+      final Isolate isolate = await _flutter.waitForPause();
       expect(isolate.pauseEvent.kind, equals(EventKind.kPauseBreakpoint));
+      expect(reloaded, isFalse);
+      await sawDebuggerPausedMessage1.future; // this is the one where it say "uh, you broke into the debugger while reloading"
+      await reloadFuture; // this is the one where it times out because you're in the debugger
+      expect(reloaded, isTrue);
+      await _flutter.hotReload(); // now we're already paused
+      expect(sawTick3.isCompleted, isFalse);
+      await sawDebuggerPausedMessage2.future; // so we just get told that nothing is going to happen
+      await _flutter.resume();
+      await subscription.cancel();
     });
-  }, timeout: const Timeout.factor(6));
+  }, timeout: const Timeout.factor(10)); // The DevFS sync takes a really long time, so these tests can be slow.
 }

packages/flutter_tools/test/integration/lifetime_test.dart

@@ -45,5 +45,5 @@ void main() {
       await Future<void>.delayed(requiredLifespan);
       expect(_flutter.hasExited, equals(false));
     });
-  }, timeout: const Timeout.factor(6));
+  }, timeout: const Timeout.factor(10)); // The DevFS sync takes a really long time, so these tests can be slow.
 }

packages/flutter_tools/test/integration/test_data/basic_project.dart

@@ -19,15 +19,22 @@ class BasicProject extends Project {
 
   @override
   final String main = r'''
+  import 'dart:async';
+
   import 'package:flutter/material.dart';
 
-  void main() => runApp(new MyApp());
+  Future<void> main() async {
+    while (true) {
+      runApp(new MyApp());
+      await Future.delayed(const Duration(milliseconds: 50));
+    }
+  }
 
   class MyApp extends StatelessWidget {
     @override
     Widget build(BuildContext context) {
       topLevelFunction();
-      return new MaterialApp( // BREAKPOINT
+      return new MaterialApp( // BUILD BREAKPOINT
         title: 'Flutter Demo',
         home: new Container(),
       );
@@ -39,9 +46,9 @@ class BasicProject extends Project {
   }
   ''';
 
-  Uri get buildMethodBreakpointUri => breakpointUri;
-  int get buildMethodBreakpointLine => breakpointLine;
+  Uri get buildMethodBreakpointUri => mainDart;
+  int get buildMethodBreakpointLine => lineContaining(main, '// BUILD BREAKPOINT');
 
-  Uri get topLevelFunctionBreakpointUri => breakpointUri;
+  Uri get topLevelFunctionBreakpointUri => mainDart;
   int get topLevelFunctionBreakpointLine => lineContaining(main, '// TOP LEVEL BREAKPOINT');
 }

packages/flutter_tools/test/integration/test_data/hot_reload_project.dart

@@ -22,33 +22,63 @@ class HotReloadProject extends Project {
   @override
   final String main = r'''
   import 'package:flutter/material.dart';
+  import 'package:flutter/scheduler.dart';
 
   void main() => runApp(new MyApp());
 
+  int count = 1;
+
   class MyApp extends StatelessWidget {
     @override
     Widget build(BuildContext context) {
-      // Do not remove this line, it's uncommented by a test to verify that hot
-      // reloading worked.
+      // This method gets called each time we hot reload, during reassemble.
+
+      // Do not remove the next line, it's uncommented by a test to verify that
+      // hot reloading worked:
       // printHotReloadWorked();
 
-      return new MaterialApp( // BREAKPOINT
+      print('((((TICK $count))))');
+      // tick 1 = startup warmup frame
+      // tick 2 = hot reload warmup reassemble frame
+      // after that there's a post-hot-reload frame scheduled by the tool that
+      // doesn't trigger this to rebuild, but does trigger the first callback
+      // below, then that callback schedules another frame on which we do the
+      // breakpoint.
+      // tick 3 = second hot reload warmup reassemble frame (pre breakpoint)
+      if (count == 2) {
+        SchedulerBinding.instance.scheduleFrameCallback((Duration timestamp) {
+          SchedulerBinding.instance.scheduleFrameCallback((Duration timestamp) {
+            print('breakpoint line'); // SCHEDULED BREAKPOINT
+          });
+        });
+      }
+      count += 1;
+
+      return MaterialApp( // BUILD BREAKPOINT
         title: 'Flutter Demo',
-        home: new Container(),
+        home: Container(),
       );
     }
   }
 
-  printHotReloadWorked() {
+  void printHotReloadWorked() {
     // The call to this function is uncommented by a test to verify that hot
     // reloading worked.
     print('(((((RELOAD WORKED)))))');
   }
   ''';
 
+  Uri get scheduledBreakpointUri => mainDart;
+  int get scheduledBreakpointLine => lineContaining(main, '// SCHEDULED BREAKPOINT');
+
+  Uri get buildBreakpointUri => mainDart;
+  int get buildBreakpointLine => lineContaining(main, '// BUILD BREAKPOINT');
+
   void uncommentHotReloadPrint() {
     final String newMainContents = main.replaceAll(
-        '// printHotReloadWorked();', 'printHotReloadWorked();');
+      '// printHotReloadWorked();',
+      'printHotReloadWorked();'
+    );
     writeFile(fs.path.join(dir.path, 'lib', 'main.dart'), newMainContents);
   }
 }

packages/flutter_tools/test/integration/test_data/project.dart

@@ -15,9 +15,7 @@ abstract class Project {
   String get pubspec;
   String get main;
 
-  // Valid locations for a breakpoint for tests that just need to break somewhere.
-  Uri get breakpointUri => Uri.parse('package:test/main.dart');
-  int get breakpointLine => lineContaining(main, '// BREAKPOINT');
+  Uri get mainDart => Uri.parse('package:test/main.dart');
 
   Future<void> setUpIn(Directory dir) async {
     this.dir = dir;
@@ -32,6 +30,6 @@ abstract class Project {
     final int index = contents.split('\n').indexWhere((String l) => l.contains(search));
     if (index == -1)
       throw Exception("Did not find '$search' inside the file");
-    return index;
+    return index + 1; // first line is line 1, not line 0
   }
 }

packages/flutter_tools/test/integration/test_data/stepping_project.dart

@@ -35,11 +35,11 @@ class SteppingProject extends Project {
 
     Future<void> doAsyncStuff() async {
       print("test"); // BREAKPOINT
-      await new Future.value(true); // STEP 1
-      await new Future.microtask(() => true); // STEP 2 // STEP 3
-      await new Future.delayed(const Duration(milliseconds: 1)); // STEP 4 // STEP 5
-      print("done!"); // STEP 6
-    }
+      await new Future.value(true); // STEP 1 // STEP 2
+      await new Future.microtask(() => true); // STEP 3 // STEP 4
+      await new Future.delayed(const Duration(milliseconds: 1)); // STEP 5 // STEP 6
+      print("done!"); // STEP 7
+    } // STEP 8
 
     @override
     Widget build(BuildContext context) {
@@ -51,7 +51,9 @@ class SteppingProject extends Project {
   }
   ''';
 
+  Uri get breakpointUri => mainDart;
+  int get breakpointLine => lineContaining(main, '// BREAKPOINT');
   int lineForStep(int i) => lineContaining(main, '// STEP $i');
 
-  final int numberOfSteps = 6;
+  final int numberOfSteps = 8;
 }

packages/flutter_tools/test/ios/code_signing_test.dart

@@ -470,7 +470,7 @@ class TestTerminal extends AnsiTerminal {
   String bolden(String message) => '<bold>$message</bold>';
 
   @override
-  Stream<String> get onCharInput {
+  Stream<String> get keystrokes {
     return mockTerminalStdInStream;
   }
 }