Enable lint prefer asserts in initializer lists (#12903)

* enable lint prefer_asserts_in_initializer_lists

* enable --assert-initializer

analysis_options.yaml

@@ -109,7 +109,7 @@ linter:
     - package_prefixed_library_names
     # - parameter_assignments # we do this commonly
     - prefer_adjacent_string_concatenation
-    # - prefer_asserts_in_initializer_lists # not yet tested
+    - prefer_asserts_in_initializer_lists
     - prefer_collection_literals
     - prefer_conditional_assignment
     - prefer_const_constructors

analysis_options_repo.yaml

@@ -103,7 +103,7 @@ linter:
     - package_prefixed_library_names
     # - parameter_assignments # we do this commonly
     - prefer_adjacent_string_concatenation
-    # - prefer_asserts_in_initializer_lists # not yet tested
+    - prefer_asserts_in_initializer_lists
     - prefer_collection_literals
     - prefer_conditional_assignment
     - prefer_const_constructors

bin/flutter.bat

@@ -39,6 +39,7 @@ IF NOT EXIST "%flutter_root%\.git" (
 REM Ensure that bin/cache exists.
 IF NOT EXIST "%cache_dir%" MKDIR "%cache_dir%"
 
+SET FLUTTER_TOOL_ARGS=--assert-initializer %FLUTTER_TOOL_ARGS%
 REM To debug the tool, you can uncomment the following lines to enable checked mode and set an observatory port:
 REM SET FLUTTER_TOOL_ARGS="--checked %FLUTTER_TOOL_ARGS%"
 REM SET FLUTTER_TOOL_ARGS="%FLUTTER_TOOL_ARGS% --observe=65432"

dev/bots/test.dart

@@ -206,7 +206,8 @@ Future<Null> _pubRunTest(
   final List<String> args = <String>['run', 'test', '-j1', '-rexpanded'];
   if (testPath != null)
     args.add(testPath);
-  return _runCommand(pub, args, workingDirectory: workingDirectory);
+  return _runCommand(pub, args, workingDirectory: workingDirectory,
+      environment: <String, String>{'DART_VM_OPTIONS': '--assert-initializer'});
 }
 
 class EvalResult {

packages/flutter/lib/src/cupertino/route.dart

@@ -89,6 +89,7 @@ class CupertinoPageRoute<T> extends PageRoute<T> {
        assert(maintainState != null),
        assert(fullscreenDialog != null),
        super(settings: settings, fullscreenDialog: fullscreenDialog) {
+    // ignore: prefer_asserts_in_initializer_lists , https://github.com/dart-lang/sdk/issues/31223
     assert(opaque); // PageRoute makes it return true.
   }
 

packages/flutter/lib/src/foundation/diagnostics.dart

@@ -642,12 +642,11 @@ abstract class DiagnosticsNode {
     this.showName: true,
     this.showSeparator: true,
   }) : assert(showName != null),
-       assert(showSeparator != null) {
+       assert(showSeparator != null),
-    // A name ending with ':' indicates that the user forgot that the ':' will
+       // A name ending with ':' indicates that the user forgot that the ':' will
-    // be automatically added for them when generating descriptions of the
+       // be automatically added for them when generating descriptions of the
-    // property.
+       // property.
-    assert(name == null || !name.endsWith(':'), 'Names of diagnostic nodes must not end with colons.');
+       assert(name == null || !name.endsWith(':'), 'Names of diagnostic nodes must not end with colons.');
-  }
 
   /// Diagnostics containing just a string `message` and not a concrete name or
   /// value.
@@ -1318,15 +1317,14 @@ class FlagProperty extends DiagnosticsProperty<bool> {
     DiagnosticLevel level: DiagnosticLevel.info,
   }) : assert(showName != null),
        assert(level != null),
+       assert(ifTrue != null || ifFalse != null),
        super(
-    name,
+         name,
-    value,
+         value,
-    showName: showName,
+         showName: showName,
-    defaultValue: defaultValue,
+         defaultValue: defaultValue,
-    level: level,
+         level: level,
-  ) {
+       );
-    assert(ifTrue != null || ifFalse != null);
-  }
 
   /// Description to use if the property [value] is true.
   ///

packages/flutter/lib/src/material/page.dart

@@ -71,6 +71,7 @@ class MaterialPageRoute<T> extends PageRoute<T> {
     bool fullscreenDialog: false,
   }) : assert(builder != null),
        super(settings: settings, fullscreenDialog: fullscreenDialog) {
+    // ignore: prefer_asserts_in_initializer_lists , https://github.com/dart-lang/sdk/issues/31223
     assert(opaque);
   }
 

packages/flutter/lib/src/painting/borders.dart

@@ -411,11 +411,10 @@ abstract class ShapeBorder {
 ///
 /// The borders are listed from the outside to the inside.
 class _CompoundBorder extends ShapeBorder {
-  _CompoundBorder(this.borders) {
+  _CompoundBorder(this.borders)
-    assert(borders != null);
+    : assert(borders != null),
-    assert(borders.length >= 2);
+      assert(borders.length >= 2),
-    assert(!borders.any((ShapeBorder border) => border is _CompoundBorder));
+      assert(!borders.any((ShapeBorder border) => border is _CompoundBorder));
-  }
 
   final List<ShapeBorder> borders;
 

packages/flutter/lib/src/widgets/localizations.dart

@@ -220,16 +220,15 @@ class DefaultWidgetsLocalizations implements WidgetsLocalizations {
 }
 
 class _LocalizationsScope extends InheritedWidget {
-  _LocalizationsScope ({
+  const _LocalizationsScope ({
     Key key,
     @required this.locale,
     @required this.localizationsState,
     @required this.typeToResources,
     Widget child,
-  }) : super(key: key, child: child) {
+  }) : assert(localizationsState != null),
-    assert(localizationsState != null);
+       assert(typeToResources != null),
-    assert(typeToResources != null);
+       super(key: key, child: child);
-  }
 
   final Locale locale;
   final _LocalizationsState localizationsState;
@@ -337,11 +336,10 @@ class Localizations extends StatefulWidget {
     @required this.locale,
     @required this.delegates,
     this.child,
-  }) : super(key: key) {
+  }) : assert(locale != null),
-    assert(locale != null);
+       assert(delegates != null),
-    assert(delegates != null);
+       assert(delegates.any((LocalizationsDelegate<dynamic> delegate) => delegate is LocalizationsDelegate<WidgetsLocalizations>)),
-    assert(delegates.any((LocalizationsDelegate<dynamic> delegate) => delegate is LocalizationsDelegate<WidgetsLocalizations>));
+       super(key: key);
-  }
 
   /// Overrides the inherited [Locale] or [LocalizationsDelegate]s for `child`.
   ///

packages/flutter/lib/src/widgets/page_storage.dart

@@ -39,9 +39,8 @@ class PageStorageKey<T> extends ValueKey<T> {
 }
 
 class _StorageEntryIdentifier {
-  _StorageEntryIdentifier(this.keys) {
+  _StorageEntryIdentifier(this.keys)
-    assert(keys != null);
+    : assert(keys != null);
-  }
 
   final List<PageStorageKey<dynamic>> keys;
 

packages/flutter/lib/src/widgets/pages.dart

@@ -83,9 +83,8 @@ class PageRouteBuilder<T> extends PageRoute<T> {
        assert(transitionsBuilder != null),
        assert(barrierDismissible != null),
        assert(maintainState != null),
-       super(settings: settings) {
+       assert(opaque != null),
-    assert(opaque != null);
+       super(settings: settings);
-  }
 
   /// Used build the route's primary contents.
   ///

packages/flutter_driver/lib/src/health.dart

@@ -33,9 +33,8 @@ final EnumIndex<HealthStatus> _healthStatusIndex =
 /// [FlutterDriver.checkHealth] test.
 class Health extends Result {
   /// Creates a [Health] object with the given [status].
-  Health(this.status) {
+  Health(this.status)
-    assert(status != null);
+    : assert(status != null);
-  }
 
   /// The status represented by this object.
   ///

packages/flutter_tools/lib/src/application_package.dart

@@ -21,9 +21,8 @@ abstract class ApplicationPackage {
   /// Package ID from the Android Manifest or equivalent.
   final String id;
 
-  ApplicationPackage({ @required this.id }) {
+  ApplicationPackage({ @required this.id })
-    assert(id != null);
+    : assert(id != null);
-  }
 
   String get name;
 
@@ -46,10 +45,9 @@ class AndroidApk extends ApplicationPackage {
     String id,
     @required this.apkPath,
     @required this.launchActivity
-  }) : super(id: id) {
+  }) : assert(apkPath != null),
-    assert(apkPath != null);
+       assert(launchActivity != null),
-    assert(launchActivity != null);
+       super(id: id);
-  }
 
   /// Creates a new AndroidApk from an existing APK.
   factory AndroidApk.fromApk(String applicationBinary) {

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

@@ -21,9 +21,8 @@ GenSnapshot get genSnapshot => context.putIfAbsent(GenSnapshot, () => const GenS
 
 /// A snapshot build configuration.
 class SnapshotType {
-  SnapshotType(this.platform, this.mode) {
+  SnapshotType(this.platform, this.mode)
-    assert(mode != null);
+    : assert(mode != null);
-  }
 
   final TargetPlatform platform;
   final BuildMode mode;

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

@@ -17,9 +17,8 @@ Flags get flags => context?.getVariable(Flags) ?? const _EmptyFlags();
 /// the Flutter tool (immediately after the arguments have been parsed in
 /// [FlutterCommandRunner]) and is available via the [flags] global property.
 class Flags {
-  Flags(this._globalResults) {
+  Flags(this._globalResults)
-    assert(_globalResults != null);
+    : assert(_globalResults != null);
-  }
 
   final ArgResults _globalResults;
 

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

@@ -177,8 +177,8 @@ class BufferLogger extends Logger {
 }
 
 class VerboseLogger extends Logger {
-  VerboseLogger(this.parent) {
+  VerboseLogger(this.parent)
-    assert(terminal != null);
+    : assert(terminal != null) {
     stopwatch.start();
   }
 

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

@@ -21,9 +21,7 @@ class ApkKeystoreInfo {
     this.password,
     this.keyAlias,
     @required this.keyPassword,
-  }) {
+  }) : assert(keystore != null);
-    assert(keystore != null);
-  }
 
   final String keystore;
   final String password;

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

@@ -297,7 +297,7 @@ Future<Null> _runTests(List<String> testArgs, String observatoryUri) async {
     ..add('-rexpanded');
   final String dartVmPath = fs.path.join(dartSdkPath, 'bin', 'dart');
   final int result = await runCommandAndStreamOutput(
-    <String>[dartVmPath]..addAll(args),
+    <String>[dartVmPath]..addAll(dartVmFlags)..addAll(args),
     environment: <String, String>{ 'VM_SERVICE_URL': observatoryUri }
   );
   if (result != 0)

packages/flutter_tools/lib/src/compile.dart

@@ -104,8 +104,8 @@ Future<String> compile(
 /// The wrapper is intended to stay resident in memory as user changes, reloads,
 /// restarts the Flutter app.
 class ResidentCompiler {
-  ResidentCompiler(this._sdkRoot) {
+  ResidentCompiler(this._sdkRoot)
-    assert(_sdkRoot != null);
+    : assert(_sdkRoot != null) {
     // This is a URI, not a file path, so the forward slash is correct even on Windows.
     if (!_sdkRoot.endsWith('/'))
       _sdkRoot = '$_sdkRoot/';

packages/flutter_tools/lib/src/dart/sdk.dart

@@ -11,6 +11,9 @@ String get dartSdkPath {
   return fs.path.join(Cache.flutterRoot, 'bin', 'cache', 'dart-sdk');
 }
 
+/// The required Dart language flags
+const List<String> dartVmFlags = const <String>['--assert-initializer'];
+
 /// Return the platform specific name for the given Dart SDK binary. So, `pub`
 /// ==> `pub.bat`.  The default SDK location can be overridden with a specified
 /// [sdkLocation].

packages/flutter_tools/lib/src/flutter_manifest.dart

@@ -102,11 +102,10 @@ class FlutterManifest {
 }
 
 class Font {
-  Font(this.familyName, this.fontAssets) {
+  Font(this.familyName, this.fontAssets)
-    assert(familyName != null);
+    : assert(familyName != null),
-    assert(fontAssets != null);
+      assert(fontAssets != null),
-    assert(fontAssets.isNotEmpty);
+      assert(fontAssets.isNotEmpty);
-  }
 
   final String familyName;
   final List<FontAsset> fontAssets;
@@ -123,9 +122,8 @@ class Font {
 }
 
 class FontAsset {
-  FontAsset(this.asset, {this.weight, this.style}) {
+  FontAsset(this.asset, {this.weight, this.style})
-    assert(asset != null);
+    : assert(asset != null);
-  }
 
   final String asset;
   final int weight;

packages/flutter_tools/lib/src/protocol_discovery.dart

@@ -18,9 +18,9 @@ class ProtocolDiscovery {
     this.portForwarder,
     this.hostPort,
     this.defaultHostPort,
-  }) : _prefix = '$serviceName listening on ' {
+  }) : assert(logReader != null),
-    assert(logReader != null);
+       assert(portForwarder == null || defaultHostPort != null),
-    assert(portForwarder == null || defaultHostPort != null);
+       _prefix = '$serviceName listening on ' {
     _deviceLogSubscription = logReader.logLines.listen(_handleLine);
   }
 

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

@@ -88,9 +88,7 @@ class _FlutterPlatform extends PlatformPlugin {
     this.startPaused,
     this.explicitObservatoryPort,
     this.host,
-  }) {
+  }) : assert(shellPath != null);
-    assert(shellPath != null);
-  }
 
   final String shellPath;
   final TestWatcher watcher;

packages/flutter_tools/test/commands/create_test.dart

@@ -209,12 +209,12 @@ void main() {
       // TODO(pq): enable when sky_shell is available
       if (!io.Platform.isWindows) {
         // Verify that the sample widget test runs cleanly.
-        final List<String> args = <String>[
+        final List<String> args = <String>[]
-          fs.path.absolute(fs.path.join('bin', 'flutter_tools.dart')),
+          ..addAll(dartVmFlags)
-          'test',
+          ..add(fs.path.absolute(fs.path.join('bin', 'flutter_tools.dart')))
-          '--no-color',
+          ..add('test')
-          fs.path.join(projectDir.path, 'test', 'widget_test.dart'),
+          ..add('--no-color')
-        ];
+          ..add(fs.path.join(projectDir.path, 'test', 'widget_test.dart'));
 
         final ProcessResult result = await Process.run(
           fs.path.join(dartSdkPath, 'bin', 'dart'),
@@ -338,7 +338,10 @@ Future<Null> _analyzeProject(String workingDir, {String target}) async {
     'flutter_tools.dart',
   ));
 
-  final List<String> args = <String>[flutterToolsPath, 'analyze'];
+  final List<String> args = <String>[]
+    ..addAll(dartVmFlags)
+    ..add(flutterToolsPath)
+    ..add('analyze');
   if (target != null)
     args.add(target);
 

packages/flutter_tools/test/commands/test_test.dart

@@ -143,11 +143,13 @@ Future<ProcessResult> _runFlutterTest(
   if (!testFile.existsSync())
     fail('missing test file: $testFile');
 
-  final List<String> args = <String>[
+  final List<String> args = <String>[]
-    fs.path.absolute(fs.path.join('bin', 'flutter_tools.dart')),
+    ..addAll(dartVmFlags)
-    'test',
+    ..add(fs.path.absolute(fs.path.join('bin', 'flutter_tools.dart')))
-    '--no-color'
+    ..add('test')
-  ]..addAll(extraArgs)..add(testFilePath);
+    ..add('--no-color')
+    ..addAll(extraArgs)
+    ..add(testFilePath);
 
   while (_testExclusionLock != null)
     await _testExclusionLock;