Declare locals as final where not reassigned (flutter_driver) (#8567)

packages/flutter_driver/lib/src/driver.dart

@@ -139,9 +139,9 @@ class FlutterDriver {
 
     // Connect to Dart VM servcies
     _log.info('Connecting to Flutter application at $dartVmServiceUrl');
-    VMServiceClientConnection connection = await vmServiceConnectFunction(dartVmServiceUrl);
-    VMServiceClient client = connection.client;
-    VM vm = await client.getVM();
+    final VMServiceClientConnection connection = await vmServiceConnectFunction(dartVmServiceUrl);
+    final VMServiceClient client = connection.client;
+    final VM vm = await client.getVM();
     _log.trace('Looking for the isolate');
     VMIsolate isolate = await vm.isolates.first.loadRunnable();
 
@@ -162,7 +162,7 @@ class FlutterDriver {
       isolate = await vm.isolates.first.loadRunnable();
     }
 
-    FlutterDriver driver = new FlutterDriver.connectedTo(
+    final FlutterDriver driver = new FlutterDriver.connectedTo(
         client, connection.peer, isolate,
         printCommunication: printCommunication,
         logCommunicationToFile: logCommunicationToFile
@@ -203,8 +203,8 @@ class FlutterDriver {
       // If the isolate is paused at the start, e.g. via the --start-paused
       // option, then the VM service extension is not registered yet. Wait for
       // it to be registered.
-      Future<dynamic> whenResumed = resumeLeniently();
-      Future<dynamic> whenServiceExtensionReady = Future.any<dynamic>(<Future<dynamic>>[
+      final Future<dynamic> whenResumed = resumeLeniently();
+      final Future<dynamic> whenServiceExtensionReady = Future.any<dynamic>(<Future<dynamic>>[
         waitForServiceExtension(),
         // We will never receive the extension event if the user does not
         // register it. If that happens time out.
@@ -212,7 +212,7 @@ class FlutterDriver {
       ]);
       await whenResumed;
       _log.trace('Waiting for service extension');
-      dynamic signal = await whenServiceExtensionReady;
+      final dynamic signal = await whenServiceExtensionReady;
       if (signal == 'timeout') {
         throw new DriverError(
           'Timed out waiting for Flutter Driver extension to become available. '
@@ -239,7 +239,7 @@ class FlutterDriver {
     }
 
     // At this point the service extension must be installed. Verify it.
-    Health health = await driver.checkHealth();
+    final Health health = await driver.checkHealth();
     if (health.status != HealthStatus.ok) {
       await client.close();
       throw new DriverError('Flutter application health check failed.');
@@ -265,7 +265,7 @@ class FlutterDriver {
   Future<Map<String, dynamic>> _sendCommand(Command command) async {
     Map<String, dynamic> response;
     try {
-      Map<String, String> serialized = command.serialize();
+      final Map<String, String> serialized = command.serialize();
       _logCommunication('>>> $serialized');
       response = await _appIsolate
           .invokeExtension(_kFlutterExtensionMethod, serialized)
@@ -293,7 +293,7 @@ class FlutterDriver {
     if (_printCommunication)
       _log.info(message);
     if (_logCommunicationToFile) {
-      f.File file = fs.file(p.join(testOutputsDirectory, 'flutter_driver_commands_$_driverId.log'));
+      final f.File file = fs.file(p.join(testOutputsDirectory, 'flutter_driver_commands_$_driverId.log'));
       file.createSync(recursive: true); // no-op if file exists
       file.writeAsStringSync('${new DateTime.now()} $message\n', mode: f.FileMode.APPEND, flush: true);
     }
@@ -329,7 +329,7 @@ class FlutterDriver {
   /// This command invokes the `onSubmitted` handler of the `Input` widget and
   /// the returns the submitted text value.
   Future<String> submitInputText(SerializableFinder finder) async {
-    Map<String, dynamic> json = await _sendCommand(new SubmitInputText(finder));
+    final Map<String, dynamic> json = await _sendCommand(new SubmitInputText(finder));
     return json['text'];
   }
 
@@ -378,7 +378,7 @@ class FlutterDriver {
 
   /// Take a screenshot.  The image will be returned as a PNG.
   Future<List<int>> screenshot() async {
-    Map<String, dynamic> result = await _peer.sendRequest('_flutter.screenshot');
+    final Map<String, dynamic> result = await _peer.sendRequest('_flutter.screenshot');
     return BASE64.decode(result['screenshot']);
   }
 
@@ -402,7 +402,7 @@ class FlutterDriver {
   ///
   /// [getFlagList]: https://github.com/dart-lang/sdk/blob/master/runtime/vm/service/service.md#getflaglist
   Future<List<Map<String, dynamic>>> getVmFlags() async {
-    Map<String, dynamic> result = await _peer.sendRequest('getFlagList');
+    final Map<String, dynamic> result = await _peer.sendRequest('getFlagList');
     return result['flags'];
   }
 
@@ -525,7 +525,7 @@ void restoreVmServiceConnectFunction() {
 ///
 /// Times out after 30 seconds.
 Future<VMServiceClientConnection> _waitAndConnect(String url) async {
-  Stopwatch timer = new Stopwatch()..start();
+  final Stopwatch timer = new Stopwatch()..start();
 
   Future<VMServiceClientConnection> attemptConnection() async {
     Uri uri = Uri.parse(url);

packages/flutter_driver/lib/src/error.dart

@@ -39,7 +39,7 @@ final StreamController<LogRecord> _logger =
     });
 
 void _log(LogLevel level, String loggerName, Object message) {
-  LogRecord record = new LogRecord._(level, loggerName, '$message');
+  final LogRecord record = new LogRecord._(level, loggerName, '$message');
   // If nobody expressed interest in rerouting log messages somewhere specific,
   // print them to stderr.
   if (_noLogSubscribers)

packages/flutter_driver/lib/src/extension.dart

@@ -29,7 +29,7 @@ class _DriverBinding extends WidgetsFlutterBinding { // TODO(ianh): refactor so
   @override
   void initServiceExtensions() {
     super.initServiceExtensions();
-    FlutterDriverExtension extension = new FlutterDriverExtension();
+    final FlutterDriverExtension extension = new FlutterDriverExtension();
     registerServiceExtension(
       name: _extensionMethodName,
       callback: extension.call
@@ -119,22 +119,22 @@ class FlutterDriverExtension {
   /// The returned JSON is command specific. Generally the caller deserializes
   /// the result into a subclass of [Result], but that's not strictly required.
   Future<Map<String, dynamic>> call(Map<String, String> params) async {
-    String commandKind = params['command'];
+    final String commandKind = params['command'];
     try {
-      CommandHandlerCallback commandHandler = _commandHandlers[commandKind];
-      CommandDeserializerCallback commandDeserializer =
+      final CommandHandlerCallback commandHandler = _commandHandlers[commandKind];
+      final CommandDeserializerCallback commandDeserializer =
           _commandDeserializers[commandKind];
       if (commandHandler == null || commandDeserializer == null)
         throw 'Extension $_extensionMethod does not support command $commandKind';
-      Command command = commandDeserializer(params);
-      Result response = await commandHandler(command).timeout(command.timeout);
+      final Command command = commandDeserializer(params);
+      final Result response = await commandHandler(command).timeout(command.timeout);
       return _makeResponse(response?.toJson());
     } on TimeoutException catch (error, stackTrace) {
-      String msg = 'Timeout while executing $commandKind: $error\n$stackTrace';
+      final String msg = 'Timeout while executing $commandKind: $error\n$stackTrace';
       _log.error(msg);
       return _makeResponse(msg, isError: true);
     } catch (error, stackTrace) {
-      String msg = 'Uncaught extension error while executing $commandKind: $error\n$stackTrace';
+      final String msg = 'Uncaught extension error while executing $commandKind: $error\n$stackTrace';
       _log.error(msg);
       return _makeResponse(msg, isError: true);
     }
@@ -185,7 +185,7 @@ class FlutterDriverExtension {
 
   Finder _createByTooltipMessageFinder(ByTooltipMessage arguments) {
     return find.byElementPredicate((Element element) {
-      Widget widget = element.widget;
+      final Widget widget = element.widget;
       if (widget is Tooltip)
         return widget.message == arguments.text;
       return false;
@@ -204,7 +204,7 @@ class FlutterDriverExtension {
   }
 
   Finder _createFinder(SerializableFinder finder) {
-    FinderConstructor constructor = _finders[finder.finderType];
+    final FinderConstructor constructor = _finders[finder.finderType];
 
     if (constructor == null)
       throw 'Unsupported finder type: ${finder.finderType}';
@@ -213,13 +213,13 @@ class FlutterDriverExtension {
   }
 
   Future<TapResult> _tap(Command command) async {
-    Tap tapCommand = command;
+    final Tap tapCommand = command;
     await _prober.tap(await _waitForElement(_createFinder(tapCommand.finder)));
     return new TapResult();
   }
 
   Future<WaitForResult> _waitFor(Command command) async {
-    WaitFor waitForCommand = command;
+    final WaitFor waitForCommand = command;
     if ((await _waitForElement(_createFinder(waitForCommand.finder))).evaluate().isNotEmpty)
       return new WaitForResult();
     else
@@ -232,15 +232,15 @@ class FlutterDriverExtension {
   }
 
   Future<ScrollResult> _scroll(Command command) async {
-    Scroll scrollCommand = command;
-    Finder target = await _waitForElement(_createFinder(scrollCommand.finder));
+    final Scroll scrollCommand = command;
+    final Finder target = await _waitForElement(_createFinder(scrollCommand.finder));
     final int totalMoves = scrollCommand.duration.inMicroseconds * scrollCommand.frequency ~/ Duration.MICROSECONDS_PER_SECOND;
-    Offset delta = new Offset(scrollCommand.dx, scrollCommand.dy) / totalMoves.toDouble();
-    Duration pause = scrollCommand.duration ~/ totalMoves;
-    Point startLocation = _prober.getCenter(target);
+    final Offset delta = new Offset(scrollCommand.dx, scrollCommand.dy) / totalMoves.toDouble();
+    final Duration pause = scrollCommand.duration ~/ totalMoves;
+    final Point startLocation = _prober.getCenter(target);
     Point currentLocation = startLocation;
-    TestPointer pointer = new TestPointer(1);
-    HitTestResult hitTest = new HitTestResult();
+    final TestPointer pointer = new TestPointer(1);
+    final HitTestResult hitTest = new HitTestResult();
 
     _prober.binding.hitTest(hitTest, startLocation);
     _prober.binding.dispatchEvent(pointer.down(startLocation), hitTest);
@@ -256,38 +256,38 @@ class FlutterDriverExtension {
   }
 
   Future<ScrollResult> _scrollIntoView(Command command) async {
-    ScrollIntoView scrollIntoViewCommand = command;
-    Finder target = await _waitForElement(_createFinder(scrollIntoViewCommand.finder));
+    final ScrollIntoView scrollIntoViewCommand = command;
+    final Finder target = await _waitForElement(_createFinder(scrollIntoViewCommand.finder));
     await Scrollable.ensureVisible(target.evaluate().single, duration: const Duration(milliseconds: 100), alignment: scrollIntoViewCommand.alignment ?? 0.0);
     return new ScrollResult();
   }
 
   Future<SetInputTextResult> _setInputText(Command command) async {
-    SetInputText setInputTextCommand = command;
-    Finder target = await _waitForElement(_createFinder(setInputTextCommand.finder));
-    Input input = target.evaluate().single.widget;
+    final SetInputText setInputTextCommand = command;
+    final Finder target = await _waitForElement(_createFinder(setInputTextCommand.finder));
+    final Input input = target.evaluate().single.widget;
     input.onChanged(new InputValue(text: setInputTextCommand.text));
     return new SetInputTextResult();
   }
 
   Future<SubmitInputTextResult> _submitInputText(Command command) async {
-    SubmitInputText submitInputTextCommand = command;
-    Finder target = await _waitForElement(_createFinder(submitInputTextCommand.finder));
-    Input input = target.evaluate().single.widget;
+    final SubmitInputText submitInputTextCommand = command;
+    final Finder target = await _waitForElement(_createFinder(submitInputTextCommand.finder));
+    final Input input = target.evaluate().single.widget;
     input.onSubmitted(input.value);
     return new SubmitInputTextResult(input.value.text);
   }
 
   Future<GetTextResult> _getText(Command command) async {
-    GetText getTextCommand = command;
-    Finder target = await _waitForElement(_createFinder(getTextCommand.finder));
+    final GetText getTextCommand = command;
+    final Finder target = await _waitForElement(_createFinder(getTextCommand.finder));
     // TODO(yjbanov): support more ways to read text
-    Text text = target.evaluate().single.widget;
+    final Text text = target.evaluate().single.widget;
     return new GetTextResult(text.data);
   }
 
   Future<SetFrameSyncResult> _setFrameSync(Command command) async {
-    SetFrameSync setFrameSyncCommand = command;
+    final SetFrameSync setFrameSyncCommand = command;
     _frameSync = setFrameSyncCommand.enabled;
     return new SetFrameSyncResult();
   }

packages/flutter_driver/lib/src/find.dart

@@ -92,7 +92,7 @@ abstract class SerializableFinder {
 
   /// Deserializes a finder from JSON generated by [serialize].
   static SerializableFinder deserialize(Map<String, String> json) {
-    String finderType = json['finderType'];
+    final String finderType = json['finderType'];
     switch(finderType) {
       case 'ByValueKey': return ByValueKey.deserialize(json);
       case 'ByTooltipMessage': return ByTooltipMessage.deserialize(json);
@@ -188,8 +188,8 @@ class ByValueKey extends SerializableFinder {
 
   /// Deserializes the finder from JSON generated by [serialize].
   static ByValueKey deserialize(Map<String, String> json) {
-    String keyValueString = json['keyValueString'];
-    String keyValueType = json['keyValueType'];
+    final String keyValueString = json['keyValueString'];
+    final String keyValueType = json['keyValueType'];
     switch(keyValueType) {
       case 'int':
         return new ByValueKey(int.parse(keyValueString));

packages/flutter_driver/lib/src/input.dart

@@ -26,7 +26,7 @@ class SetInputText extends CommandWithTarget {
 
   @override
   Map<String, String> serialize() {
-    Map<String, String> json = super.serialize();
+    final Map<String, String> json = super.serialize();
     json['text'] = text;
     return json;
   }

packages/flutter_driver/lib/src/matcher_util.dart

@@ -6,11 +6,11 @@ import 'package:matcher/matcher.dart';
 
 /// Matches [value] against the [matcher].
 MatchResult match(dynamic value, Matcher matcher) {
-  Map<dynamic, dynamic> matchState = <dynamic, dynamic>{};
+  final Map<dynamic, dynamic> matchState = <dynamic, dynamic>{};
   if (matcher.matches(value, matchState)) {
     return new MatchResult._matched();
   } else {
-    Description description =
+    final Description description =
         matcher.describeMismatch(value, new _TextDescription(), matchState, false);
     return new MatchResult._mismatched(description.toString());
   }

packages/flutter_driver/lib/src/retry.dart

@@ -23,7 +23,7 @@ Future<dynamic> retry(Action action, Duration timeout,
   assert(timeout != null);
   assert(pauseBetweenRetries != null);
 
-  Stopwatch sw = stopwatchFactory()..start();
+  final Stopwatch sw = stopwatchFactory()..start();
   dynamic result;
   dynamic lastError;
   dynamic lastStackTrace;

packages/flutter_driver/lib/src/timeline.dart

@@ -122,7 +122,7 @@ class TimelineEvent {
 }
 
 List<TimelineEvent> _parseEvents(Map<String, dynamic> json) {
-  List<Map<String, dynamic>> jsonEvents = json['traceEvents'];
+  final List<Map<String, dynamic>> jsonEvents = json['traceEvents'];
 
   if (jsonEvents == null)
     return null;

packages/flutter_driver/lib/src/timeline_summary.dart

@@ -93,7 +93,7 @@ class TimelineSummary {
       {String destinationDirectory, bool pretty: false}) async {
     destinationDirectory ??= testOutputsDirectory;
     await fs.directory(destinationDirectory).create(recursive: true);
-    File file = fs.file(path.join(destinationDirectory, '$traceName.timeline.json'));
+    final File file = fs.file(path.join(destinationDirectory, '$traceName.timeline.json'));
     await file.writeAsString(_encodeJson(_timeline.json, pretty));
   }
 
@@ -102,7 +102,7 @@ class TimelineSummary {
       {String destinationDirectory, bool pretty: false}) async {
     destinationDirectory ??= testOutputsDirectory;
     await fs.directory(destinationDirectory).create(recursive: true);
-    File file = fs.file(path.join(destinationDirectory, '$traceName.timeline_summary.json'));
+    final File file = fs.file(path.join(destinationDirectory, '$traceName.timeline_summary.json'));
     await file.writeAsString(_encodeJson(summaryJson, pretty));
   }
 
@@ -127,15 +127,15 @@ class TimelineSummary {
   ///
   /// See: https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU
   List<TimedEvent> _extractBeginEndEvents(String name) {
-    List<TimedEvent> result = <TimedEvent>[];
+    final List<TimedEvent> result = <TimedEvent>[];
 
     // Timeline does not guarantee that the first event is the "begin" event.
-    Iterator<TimelineEvent> events = _extractNamedEvents(name)
+    final Iterator<TimelineEvent> events = _extractNamedEvents(name)
         .skipWhile((TimelineEvent evt) => evt.phase != 'B').iterator;
     while(events.moveNext()) {
-      TimelineEvent beginEvent = events.current;
+      final TimelineEvent beginEvent = events.current;
       if (events.moveNext()) {
-        TimelineEvent endEvent = events.current;
+        final TimelineEvent endEvent = events.current;
         result.add(new TimedEvent(
             beginEvent.timestampMicros,
             endEvent.timestampMicros
@@ -150,7 +150,7 @@ class TimelineSummary {
     if (durations.isEmpty)
       return null;
 
-    int total = durations.fold<int>(0, (int t, Duration duration) => t + duration.inMilliseconds);
+    final int total = durations.fold<int>(0, (int t, Duration duration) => t + duration.inMilliseconds);
     return total / durations.length;
   }
 

packages/flutter_driver/test/flutter_driver_test.dart

@@ -53,7 +53,7 @@ void main() {
       when(mockIsolate.resume()).thenReturn(new Future<Null>.value());
       when(mockIsolate.onExtensionAdded).thenReturn(new Stream<String>.fromIterable(<String>['ext.flutter.driver']));
 
-      FlutterDriver driver = await FlutterDriver.connect(dartVmServiceUrl: '');
+      final FlutterDriver driver = await FlutterDriver.connect(dartVmServiceUrl: '');
       expect(driver, isNotNull);
       expectLogContains('Isolate is paused at start');
     });
@@ -62,7 +62,7 @@ void main() {
       when(mockIsolate.pauseEvent).thenReturn(new MockVMPauseBreakpointEvent());
       when(mockIsolate.resume()).thenReturn(new Future<Null>.value());
 
-      FlutterDriver driver = await FlutterDriver.connect(dartVmServiceUrl: '');
+      final FlutterDriver driver = await FlutterDriver.connect(dartVmServiceUrl: '');
       expect(driver, isNotNull);
       expectLogContains('Isolate is paused mid-flight');
     });
@@ -79,14 +79,14 @@ void main() {
         return new Future<Null>.error(new rpc.RpcException(101, ''));
       });
 
-      FlutterDriver driver = await FlutterDriver.connect(dartVmServiceUrl: '');
+      final FlutterDriver driver = await FlutterDriver.connect(dartVmServiceUrl: '');
       expect(driver, isNotNull);
       expectLogContains('Attempted to resume an already resumed isolate');
     });
 
     test('connects to unpaused isolate', () async {
       when(mockIsolate.pauseEvent).thenReturn(new MockVMResumeEvent());
-      FlutterDriver driver = await FlutterDriver.connect(dartVmServiceUrl: '');
+      final FlutterDriver driver = await FlutterDriver.connect(dartVmServiceUrl: '');
       expect(driver, isNotNull);
       expectLogContains('Isolate is not paused. Assuming application is ready.');
     });
@@ -108,7 +108,7 @@ void main() {
     test('checks the health of the driver extension', () async {
       when(mockIsolate.invokeExtension(any, any)).thenReturn(
           makeMockResponse(<String, dynamic>{'status': 'ok'}));
-      Health result = await driver.checkHealth();
+      final Health result = await driver.checkHealth();
       expect(result.status, HealthStatus.ok);
     });
 
@@ -175,7 +175,7 @@ void main() {
             'text': 'hello'
           });
         });
-        String result = await driver.getText(find.byValueKey(123));
+        final String result = await driver.getText(find.byValueKey(123));
         expect(result, 'hello');
       });
     });
@@ -240,7 +240,7 @@ void main() {
           };
         });
 
-        Timeline timeline = await driver.traceAction(() {
+        final Timeline timeline = await driver.traceAction(() {
           actionCalled = true;
         });
 
@@ -279,7 +279,7 @@ void main() {
           };
         });
 
-        Timeline timeline = await driver.traceAction(() {
+        final Timeline timeline = await driver.traceAction(() {
           actionCalled = true;
         },
         streams: const <TimelineStream>[

packages/flutter_driver/test/src/matcher_util_test.dart

@@ -8,8 +8,8 @@ import 'package:flutter_driver/src/matcher_util.dart';
 void main() {
   group('match', () {
     test('matches', () {
-      _TestMatcher matcher = new _TestMatcher(1);
-      MatchResult ok = match(1, matcher);
+      final _TestMatcher matcher = new _TestMatcher(1);
+      final MatchResult ok = match(1, matcher);
       expect(ok.hasMatched, isTrue);
       expect(ok.mismatchDescription, isNull);
       expect(matcher.matchState1 is Map<dynamic, dynamic>, isTrue);
@@ -17,8 +17,8 @@ void main() {
     });
 
     test('mismatches', () {
-      _TestMatcher matcher = new _TestMatcher(2);
-      MatchResult fail = match(1, matcher);
+      final _TestMatcher matcher = new _TestMatcher(2);
+      final MatchResult fail = match(1, matcher);
       expect(fail.hasMatched, isFalse);
       expect(fail.mismatchDescription, 'mismatch!');
       expect(matcher.matchState1, matcher.matchState2);

packages/flutter_driver/test/src/retry_test.dart

@@ -15,7 +15,7 @@ void main() {
 
     setUp(() {
       fakeAsync = new FakeAsync();
-      Clock fakeClock = fakeAsync.getClock(new DateTime.now());
+      final Clock fakeClock = fakeAsync.getClock(new DateTime.now());
       stopwatchFactory = () {
         return new FakeStopwatch(
           () => fakeClock.now().millisecondsSinceEpoch,

packages/flutter_driver/test/src/timeline_summary_test.dart

@@ -84,7 +84,7 @@ void main() {
 
     group('computeMissedFrameBuildBudgetCount', () {
       test('computes the number of missed build budgets', () {
-        TimelineSummary summary = summarize(<Map<String, dynamic>>[
+        final TimelineSummary summary = summarize(<Map<String, dynamic>>[
           build(1000, 9000),
           build(11000, 1000),
           build(13000, 10000),
@@ -176,7 +176,7 @@ void main() {
 
     group('computeMissedFrameRasterizerBudgetCount', () {
       test('computes the number of missed rasterizer budgets', () {
-        TimelineSummary summary = summarize(<Map<String, dynamic>>[
+        final TimelineSummary summary = summarize(<Map<String, dynamic>>[
           begin(1000), end(10000),
           begin(11000), end(12000),
           begin(13000), end(23000),
@@ -229,7 +229,7 @@ void main() {
       test('writes timeline to JSON file', () async {
         await summarize(<Map<String, String>>[<String, String>{'foo': 'bar'}])
           .writeTimelineToFile('test', destinationDirectory: tempDir.path);
-        String written =
+        final String written =
             await fs.file(path.join(tempDir.path, 'test.timeline.json')).readAsString();
         expect(written, '{"traceEvents":[{"foo":"bar"}]}');
       });
@@ -243,7 +243,7 @@ void main() {
           build(11000, 1000),
           build(13000, 11000),
         ]).writeSummaryToFile('test', destinationDirectory: tempDir.path);
-        String written =
+        final String written =
             await fs.file(path.join(tempDir.path, 'test.timeline_summary.json')).readAsString();
         expect(JSON.decode(written), <String, dynamic>{
           'average_frame_build_time_millis': 7.0,

packages/flutter_driver/test/src/timeline_test.dart

@@ -8,7 +8,7 @@ import 'package:flutter_driver/src/timeline.dart';
 void main() {
   group('Timeline', () {
     test('parses JSON', () {
-      Timeline timeline = new Timeline.fromJson(<String, dynamic>{
+      final Timeline timeline = new Timeline.fromJson(<String, dynamic>{
         'traceEvents': <Map<String, dynamic>>[
           <String, dynamic>{
             'name': 'test event',
@@ -31,7 +31,7 @@ void main() {
 
       expect(timeline.events, hasLength(2));
 
-      TimelineEvent e1 = timeline.events[0];
+      final TimelineEvent e1 = timeline.events[0];
       expect(e1.name, 'test event');
       expect(e1.category, 'test category');
       expect(e1.phase, 'B');
@@ -43,7 +43,7 @@ void main() {
       expect(e1.threadTimestampMicros, 567);
       expect(e1.arguments, <String, dynamic>{ 'arg1': true });
 
-      TimelineEvent e2 = timeline.events[1];
+      final TimelineEvent e2 = timeline.events[1];
       expect(e2.name, isNull);
       expect(e2.category, isNull);
       expect(e2.phase, isNull);