Some minor cleanup for flutter_tools (#36569)

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

@@ -26,7 +26,7 @@
 /// increase the API surface that we have to test in Flutter tools, and the APIs
 /// in `dart:io` can sometimes be hard to use in tests.
 import 'dart:async';
-import 'dart:io' as io show exit, IOSink, ProcessSignal, stderr, stdin, Stdout, stdout;
+import 'dart:io' as io show exit, IOSink, Process, ProcessSignal, stderr, stdin, Stdout, stdout;
 
 import 'package:meta/meta.dart';
 
@@ -116,7 +116,12 @@ void restoreExitFunction() {
 /// Listening on signals that don't exist on the current platform is just a
 /// no-op. This is in contrast to [io.ProcessSignal], where listening to
 /// non-existent signals throws an exception.
-class ProcessSignal implements io.ProcessSignal {
+///
+/// This class does NOT implement io.ProcessSignal, because that class uses
+/// private fields. This means it cannot be used with, e.g., [Process.killPid].
+/// Alternative implementations of the relevant methods that take
+/// [ProcessSignal] instances are available on this class (e.g. "send").
+class ProcessSignal {
   @visibleForTesting
   const ProcessSignal(this._delegate);
 
@@ -129,11 +134,23 @@ class ProcessSignal implements io.ProcessSignal {
 
   final io.ProcessSignal _delegate;
 
-  @override
   Stream<ProcessSignal> watch() {
     return _delegate.watch().map<ProcessSignal>((io.ProcessSignal signal) => this);
   }
 
+  /// Sends the signal to the given process (identified by pid).
+  ///
+  /// Returns true if the signal was delivered, false otherwise.
+  ///
+  /// On Windows, this can only be used with [ProcessSignal.SIGTERM], which
+  /// terminates the process.
+  ///
+  /// This is implemented by sending the signal using [Process.killPid].
+  bool send(int pid) {
+    assert(!platform.isWindows || this == ProcessSignal.SIGTERM);
+    return io.Process.killPid(pid, _delegate);
+  }
+
   @override
   String toString() => _delegate.toString();
 }

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

@@ -89,16 +89,13 @@ class AttachCommand extends FlutterCommand {
         'project-root',
         hide: !verboseHelp,
         help: 'Normally used only in run target',
-      )..addFlag('track-widget-creation',
-        hide: !verboseHelp,
-        help: 'Track widget creation locations.',
-        defaultsTo: false,
       )..addFlag('machine',
         hide: !verboseHelp,
         negatable: false,
         help: 'Handle machine structured JSON command input and provide output '
               'and progress in machine friendly format.',
       );
+    usesTrackWidgetCreation(verboseHelp: verboseHelp);
     hotRunnerFactory ??= HotRunnerFactory();
   }
 

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

@@ -23,7 +23,7 @@ class BuildCommand extends FlutterCommand {
     addSubcommand(BuildAarCommand(verboseHelp: verboseHelp));
     addSubcommand(BuildApkCommand(verboseHelp: verboseHelp));
     addSubcommand(BuildAppBundleCommand(verboseHelp: verboseHelp));
-    addSubcommand(BuildAotCommand());
+    addSubcommand(BuildAotCommand(verboseHelp: verboseHelp));
     addSubcommand(BuildIOSCommand());
     addSubcommand(BuildBundleCommand(verboseHelp: verboseHelp));
     addSubcommand(BuildWebCommand());

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

@@ -21,7 +21,7 @@ import '../runner/flutter_command.dart';
 import 'build.dart';
 
 class BuildAotCommand extends BuildSubCommand with TargetPlatformBasedDevelopmentArtifacts {
-  BuildAotCommand() {
+  BuildAotCommand({bool verboseHelp = false}) {
     usesTargetOption();
     addBuildModeFlags();
     usesPubOption();
@@ -37,12 +37,6 @@ class BuildAotCommand extends BuildSubCommand with TargetPlatformBasedDevelopmen
         defaultsTo: false,
         help: 'Report timing information about build steps in machine readable form,',
       )
-      // track-widget-creation is exposed as a flag here but ignored to deal with build
-      // invalidation issues - there are no plans to support it for AOT mode.
-      ..addFlag('track-widget-creation',
-        defaultsTo: false,
-        hide: true,
-      )
       ..addMultiOption('ios-arch',
         splitCommas: true,
         defaultsTo: defaultIOSArchs.map<String>(getNameForIOSArch),
@@ -62,6 +56,10 @@ class BuildAotCommand extends BuildSubCommand with TargetPlatformBasedDevelopmen
         help: 'Build the AOT bundle with bitcode. Requires a compatible bitcode engine.',
         hide: true,
       );
+    // --track-widget-creation is exposed as a flag here to deal with build
+    // invalidation issues, but it is ignored -- there are no plans to support
+    // it for AOT mode.
+    usesTrackWidgetCreation(hasEffect: false, verboseHelp: verboseHelp);
   }
 
   @override

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

@@ -22,7 +22,6 @@ class BuildApkCommand extends BuildSubCommand {
     usesBuildNameOption();
 
     argParser
-      ..addFlag('track-widget-creation', negatable: false, hide: !verboseHelp)
       ..addFlag('split-per-abi',
         negatable: false,
         help: 'Whether to split the APKs per ABIs.'
@@ -34,6 +33,7 @@ class BuildApkCommand extends BuildSubCommand {
         allowed: <String>['android-arm', 'android-arm64', 'android-x86', 'android-x64'],
         help: 'The target platform for which the app is compiled.',
       );
+    usesTrackWidgetCreation(verboseHelp: verboseHelp);
   }
 
   @override

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

@@ -41,10 +41,6 @@ class BuildBundleCommand extends BuildSubCommand {
           'windows-x64',
         ],
       )
-      ..addFlag('track-widget-creation',
-        hide: !verboseHelp,
-        help: 'Track widget creation locations. Requires Dart 2.0 functionality.',
-      )
       ..addMultiOption(FlutterOptions.kExtraFrontEndOptions,
         splitCommas: true,
         hide: true,
@@ -59,6 +55,7 @@ class BuildBundleCommand extends BuildSubCommand {
               'in the application\'s LICENSE file.',
         defaultsTo: false);
     usesPubOption();
+    usesTrackWidgetCreation(verboseHelp: verboseHelp);
 
     bundleBuilder ??= BundleBuilder();
   }

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

@@ -49,6 +49,7 @@ abstract class RunCommandBase extends FlutterCommand with DeviceBasedDevelopment
     usesPortOptions();
     usesIpv6Flag();
     usesPubOption();
+    usesTrackWidgetCreation(verboseHelp: verboseHelp);
     usesIsolateFilterOption(hide: !verboseHelp);
   }
 
@@ -61,7 +62,6 @@ class RunCommand extends RunCommandBase {
   RunCommand({ bool verboseHelp = false }) : super(verboseHelp: verboseHelp) {
     requiresPubspecYaml();
     usesFilesystemOptions(hide: !verboseHelp);
-
     argParser
       ..addFlag('start-paused',
         negatable: false,
@@ -130,10 +130,6 @@ class RunCommand extends RunCommandBase {
         hide: !verboseHelp,
         help: 'Specify a pre-built application binary to use when running.',
       )
-      ..addFlag('track-widget-creation',
-        hide: !verboseHelp,
-        help: 'Track widget creation locations.',
-      )
       ..addOption('project-root',
         hide: !verboseHelp,
         help: 'Specify the project root directory.',

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

@@ -78,12 +78,6 @@ class TestCommand extends FastFlutterCommand {
         help: 'Handle machine structured JSON command input\n'
               'and provide output and progress in machine friendly format.',
       )
-      ..addFlag('track-widget-creation',
-        negatable: false,
-        hide: !verboseHelp,
-        help: 'Track widget creation locations.\n'
-              'This enables testing of features such as the widget inspector.',
-      )
       ..addFlag('update-goldens',
         negatable: false,
         help: 'Whether matchesGoldenFile() calls within your test methods should '
@@ -106,6 +100,7 @@ class TestCommand extends FastFlutterCommand {
         defaultsTo: 'tester',
         help: 'The platform to run the unit tests on. Defaults to "tester".'
       );
+    usesTrackWidgetCreation(verboseHelp: verboseHelp);
   }
 
   @override

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

@@ -119,10 +119,11 @@ Future<void> pubGet({
   }
 
   if (!dotPackages.existsSync())
-    throwToolExit('$directory: pub did not create .packages file');
+    throwToolExit('$directory: pub did not create .packages file.');
 
-  if (dotPackages.lastModifiedSync().isBefore(pubSpecYaml.lastModifiedSync()))
-    throwToolExit('$directory: pub did not update .packages file (pubspec.yaml file has a newer timestamp)');
+  if (dotPackages.lastModifiedSync().isBefore(pubSpecYaml.lastModifiedSync())) {
+    throwToolExit('$directory: pub did not update .packages file (pubspec.yaml timestamp: ${pubSpecYaml.lastModifiedSync()}; .packages timestamp: ${dotPackages.lastModifiedSync()}).');
+  }
 }
 
 typedef MessageFilter = String Function(String message);

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

@@ -288,8 +288,18 @@ abstract class FlutterCommand extends Command<void> {
     argParser.addOption(
       'flavor',
       help: 'Build a custom app flavor as defined by platform-specific build setup.\n'
-        'Supports the use of product flavors in Android Gradle scripts.\n'
-        'Supports the use of custom Xcode schemes.',
+            'Supports the use of product flavors in Android Gradle scripts, and '
+            'the use of custom Xcode schemes.',
+    );
+  }
+
+  void usesTrackWidgetCreation({ bool hasEffect = true, @required bool verboseHelp }) {
+    argParser.addFlag(
+      'track-widget-creation',
+      hide: !hasEffect && !verboseHelp,
+      defaultsTo: false, // this will soon be changed to true
+      help: 'Track widget creation locations. This enables features such as the widget inspector. '
+            'This parameter is only functional in debug mode (i.e. when compiling JIT, not AOT).',
     );
   }
 
@@ -384,7 +394,6 @@ abstract class FlutterCommand extends Command<void> {
         } finally {
           final DateTime endTime = systemClock.now();
           printTrace(userMessages.flutterElapsedTime(name, getElapsedAsMilliseconds(endTime.difference(startTime))));
-          printTrace('"flutter $name" took ${getElapsedAsMilliseconds(endTime.difference(startTime))}.');
           _sendPostUsage(commandPath, commandResult, startTime, endTime);
         }
       },

packages/flutter_tools/test/integration.shard/README.md

 # Integration tests
 
-These tests are not hermetic, and use actual Flutter SDK.
-While they don't require actual devices, they run `flutter_tester` to test
+These tests are not hermetic, and use the actual Flutter SDK. While
+they don't require actual devices, they run `flutter_tester` to test
 Dart VM and Flutter integration.
 
-Use this command to run:
+Use this command to run (from the `flutter_tools` directory):
 
 ```shell
-../../bin/cache/dart-sdk/bin/pub run test
+../../bin/cache/dart-sdk/bin/pub run test test/integration.shard
 ```
+
+These tests are expensive to run and do not give meaningful coverage
+information for the flutter tool (since they are black-box tests that
+run the tool as a subprocess, rather than being unit tests). For this
+reason, they are in a separate shard when running on continuous
+integration and are not run when calculating coverage.

packages/flutter_tools/test/integration.shard/test_driver.dart

@@ -152,13 +152,13 @@ abstract class FlutterTestDriver {
     if (_processPid == null)
       return -1;
     _debugPrint('Sending SIGTERM to $_processPid..');
-    Process.killPid(_processPid);
+    ProcessSignal.SIGTERM.send(_processPid);
     return _process.exitCode.timeout(quitTimeout, onTimeout: _killForcefully);
   }
 
   Future<int> _killForcefully() {
     _debugPrint('Sending SIGKILL to $_processPid..');
-    Process.killPid(_processPid, ProcessSignal.SIGKILL);
+    ProcessSignal.SIGKILL.send(_processPid);
     return _process.exitCode;
   }
 
@@ -655,6 +655,7 @@ class FlutterTestTestDriver extends FlutterTestDriver {
   Future<Map<String, dynamic>> _waitForJson({
     Duration timeout = defaultTimeout,
   }) async {
+    assert(timeout != null);
     return _timeoutWithMessages<Map<String, dynamic>>(
       () => _stdout.stream.map<Map<String, dynamic>>(_parseJsonResponse)
           .firstWhere((Map<String, dynamic> output) => output != null),

packages/flutter_tools/test/integration.shard/test_utils.dart

@@ -51,6 +51,5 @@ Future<void> getPackages(String folder) async {
   process.stderr.transform(utf8.decoder).listen(errorOutput.write);
   final int exitCode = await process.exitCode;
   if (exitCode != 0)
-    throw Exception(
-        'flutter pub get failed: ${errorOutput.toString()}');
+    throw Exception('flutter pub get failed: $errorOutput');
 }

packages/flutter_tools/test/src/context.dart

@@ -91,7 +91,6 @@ void testUsingContext(
         },
         body: () {
           final String flutterRoot = getFlutterRoot();
-
           return runZoned<Future<dynamic>>(() {
             try {
               return context.run<dynamic>(
@@ -105,7 +104,6 @@ void testUsingContext(
                     // tests can override this either in the test or during setup.
                     Cache.flutterRoot ??= flutterRoot;
                   }
-
                   return await testMethod();
                 },
               );

packages/flutter_tools/test/src/testbed.dart

@@ -25,15 +25,11 @@ import 'context.dart';
 
 export 'package:flutter_tools/src/base/context.dart' show Generator;
 
-// A default value should be provided if one of the following criteria is met:
-//    - The vast majority of tests should use this provider. For example,
-//      [BufferLogger], [MemoryFileSystem].
-//    - More TBD.
+// A default value should be provided if the vast majority of tests should use
+// this provider. For example, [BufferLogger], [MemoryFileSystem].
 final Map<Type, Generator> _testbedDefaults = <Type, Generator>{
-  // Keeps tests fast by avoid actual file system.
-  FileSystem: () => MemoryFileSystem(style: platform.isWindows
-      ? FileSystemStyle.windows
-      : FileSystemStyle.posix),
+  // Keeps tests fast by avoiding the actual file system.
+  FileSystem: () => MemoryFileSystem(style: platform.isWindows ? FileSystemStyle.windows : FileSystemStyle.posix),
   Logger: () => BufferLogger(), // Allows reading logs and prevents stdout.
   OperatingSystemUtils: () => FakeOperatingSystemUtils(),
   OutputPreferences: () => OutputPreferences(showColor: false), // configures BufferLogger to avoid color codes.