diff --git a/packages/flutter_driver/lib/src/common/find.dart b/packages/flutter_driver/lib/src/common/find.dart
index ee16f78fa83..3423876df60 100644
--- a/packages/flutter_driver/lib/src/common/find.dart
+++ b/packages/flutter_driver/lib/src/common/find.dart
@@ -59,14 +59,17 @@ class WaitFor extends CommandWithTarget {
   WaitFor.deserialize(Map<String, String> json) : super.deserialize(json);
 
   @override
-  final String kind = 'waitFor';
+  String get kind => 'waitFor';
 }
 
 /// The result of a [WaitFor] command.
 class WaitForResult extends Result {
+  /// Creates a [WaitForResult].
+  const WaitForResult();
+
   /// Deserializes the result from JSON.
   static WaitForResult fromJson(Map<String, dynamic> json) {
-    return WaitForResult();
+    return const WaitForResult();
   }
 
   @override
@@ -86,14 +89,17 @@ class WaitForAbsent extends CommandWithTarget {
   WaitForAbsent.deserialize(Map<String, String> json) : super.deserialize(json);
 
   @override
-  final String kind = 'waitForAbsent';
+  String get kind => 'waitForAbsent';
 }
 
 /// The result of a [WaitForAbsent] command.
 class WaitForAbsentResult extends Result {
+  /// Creates a [WaitForAbsentResult].
+  const WaitForAbsentResult();
+
   /// Deserializes the result from JSON.
   static WaitForAbsentResult fromJson(Map<String, dynamic> json) {
-    return WaitForAbsentResult();
+    return const WaitForAbsentResult();
   }
 
   @override
@@ -103,19 +109,23 @@ class WaitForAbsentResult extends Result {
 /// A Flutter Driver command that waits until there are no more transient callbacks in the queue.
 class WaitUntilNoTransientCallbacks extends Command {
   /// Creates a command that waits for there to be no transient callbacks.
-  WaitUntilNoTransientCallbacks({ Duration timeout }) : super(timeout: timeout);
+  const WaitUntilNoTransientCallbacks({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   WaitUntilNoTransientCallbacks.deserialize(Map<String, String> json)
     : super.deserialize(json);
 
   @override
-  final String kind = 'waitUntilNoTransientCallbacks';
+  String get kind => 'waitUntilNoTransientCallbacks';
 }
 
 /// Base class for Flutter Driver finders, objects that describe how the driver
 /// should search for elements.
 abstract class SerializableFinder {
+
+  /// A const constructor to allow subclasses to be const.
+  const SerializableFinder();
+
   /// Identifies the type of finder to be used by the driver extension.
   String get finderType;
 
@@ -137,7 +147,7 @@ abstract class SerializableFinder {
       case 'ByTooltipMessage': return ByTooltipMessage.deserialize(json);
       case 'BySemanticsLabel': return BySemanticsLabel.deserialize(json);
       case 'ByText': return ByText.deserialize(json);
-      case 'PageBack': return PageBack();
+      case 'PageBack': return const PageBack();
     }
     throw DriverError('Unsupported search specification type $finderType');
   }
@@ -146,13 +156,13 @@ abstract class SerializableFinder {
 /// A Flutter Driver finder that finds widgets by tooltip text.
 class ByTooltipMessage extends SerializableFinder {
   /// Creates a tooltip finder given the tooltip's message [text].
-  ByTooltipMessage(this.text);
+  const ByTooltipMessage(this.text);
 
   /// Tooltip message text.
   final String text;
 
   @override
-  final String finderType = 'ByTooltipMessage';
+  String get finderType => 'ByTooltipMessage';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -171,7 +181,7 @@ class ByTooltipMessage extends SerializableFinder {
 /// match. If it is a [RegExp], it will return true for [RegExp.hasMatch].
 class BySemanticsLabel extends SerializableFinder {
   /// Creates a semantic label finder given the [label].
-  BySemanticsLabel(this.label);
+  const BySemanticsLabel(this.label);
 
   /// A [Pattern] matching the [Semantics.properties.label].
   ///
@@ -179,7 +189,7 @@ class BySemanticsLabel extends SerializableFinder {
   final Pattern label;
 
   @override
-  final String finderType = 'BySemanticsLabel';
+  String get finderType => 'BySemanticsLabel';
 
   @override
   Map<String, String> serialize() {
@@ -207,13 +217,13 @@ class BySemanticsLabel extends SerializableFinder {
 /// [EditableText] widget.
 class ByText extends SerializableFinder {
   /// Creates a text finder given the text.
-  ByText(this.text);
+  const ByText(this.text);
 
   /// The text that appears inside the [Text] or [EditableText] widget.
   final String text;
 
   @override
-  final String finderType = 'ByText';
+  String get finderType => 'ByText';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -248,7 +258,7 @@ class ByValueKey extends SerializableFinder {
   final String keyValueType;
 
   @override
-  final String finderType = 'ByValueKey';
+  String get finderType => 'ByValueKey';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -274,13 +284,13 @@ class ByValueKey extends SerializableFinder {
 /// A Flutter Driver finder that finds widgets by their [runtimeType].
 class ByType extends SerializableFinder {
   /// Creates a finder that given the runtime type in string form.
-  ByType(this.type);
+  const ByType(this.type);
 
   /// The widget's [runtimeType], in string form.
   final String type;
 
   @override
-  final String finderType = 'ByType';
+  String get finderType => 'ByType';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -300,6 +310,9 @@ class ByType extends SerializableFinder {
 ///
 ///  * [WidgetTester.pageBack], for a similar functionality in widget tests.
 class PageBack extends SerializableFinder {
+  /// Creates a [PageBack].
+  const PageBack();
+
   @override
   String get finderType => 'PageBack';
 }
@@ -333,7 +346,7 @@ class GetSemanticsId extends CommandWithTarget {
 class GetSemanticsIdResult extends Result {
 
   /// Creates a new [GetSemanticsId] result.
-  GetSemanticsIdResult(this.id);
+  const GetSemanticsIdResult(this.id);
 
   /// The semantics id of the node;
   final int id;
diff --git a/packages/flutter_driver/lib/src/common/frame_sync.dart b/packages/flutter_driver/lib/src/common/frame_sync.dart
index add70fb4550..78e4c634baa 100644
--- a/packages/flutter_driver/lib/src/common/frame_sync.dart
+++ b/packages/flutter_driver/lib/src/common/frame_sync.dart
@@ -7,7 +7,7 @@ import 'message.dart';
 /// A Flutter Driver command that enables or disables the FrameSync mechanism.
 class SetFrameSync extends Command {
   /// Creates a command to toggle the FrameSync mechanism.
-  SetFrameSync(this.enabled, { Duration timeout }) : super(timeout: timeout);
+  const SetFrameSync(this.enabled, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   SetFrameSync.deserialize(Map<String, String> params)
@@ -18,7 +18,7 @@ class SetFrameSync extends Command {
   final bool enabled;
 
   @override
-  final String kind = 'set_frame_sync';
+  String get kind => 'set_frame_sync';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -28,9 +28,12 @@ class SetFrameSync extends Command {
 
 /// The result of a [SetFrameSync] command.
 class SetFrameSyncResult extends Result {
+  /// Creates a [SetFrameSyncResult].
+  const SetFrameSyncResult();
+
   /// Deserializes this result from JSON.
   static SetFrameSyncResult fromJson(Map<String, dynamic> json) {
-    return SetFrameSyncResult();
+    return const SetFrameSyncResult();
   }
 
   @override
diff --git a/packages/flutter_driver/lib/src/common/geometry.dart b/packages/flutter_driver/lib/src/common/geometry.dart
index cfedb9e4659..90318bd4a3c 100644
--- a/packages/flutter_driver/lib/src/common/geometry.dart
+++ b/packages/flutter_driver/lib/src/common/geometry.dart
@@ -47,13 +47,13 @@ class GetOffset extends CommandWithTarget {
   final OffsetType offsetType;
 
   @override
-  final String kind = 'get_offset';
+  String get kind => 'get_offset';
 }
 
 /// The result of the [GetRect] command.
 class GetOffsetResult extends Result {
   /// Creates a result with the offset defined by [dx] and [dy].
-  GetOffsetResult({ this.dx = 0.0, this.dy = 0.0});
+  const GetOffsetResult({ this.dx = 0.0, this.dy = 0.0});
 
   /// The x component of the offset.
   final double dx;
diff --git a/packages/flutter_driver/lib/src/common/gesture.dart b/packages/flutter_driver/lib/src/common/gesture.dart
index 7dabd3f57af..e771cda0fb1 100644
--- a/packages/flutter_driver/lib/src/common/gesture.dart
+++ b/packages/flutter_driver/lib/src/common/gesture.dart
@@ -14,14 +14,17 @@ class Tap extends CommandWithTarget {
   Tap.deserialize(Map<String, String> json) : super.deserialize(json);
 
   @override
-  final String kind = 'tap';
+  String get kind => 'tap';
 }
 
 /// The result of a [Tap] command.
 class TapResult extends Result {
+  /// Creates a [TapResult].
+  const TapResult();
+
   /// Deserializes this result from JSON.
   static TapResult fromJson(Map<String, dynamic> json) {
-    return TapResult();
+    return const TapResult();
   }
 
   @override
@@ -63,7 +66,7 @@ class Scroll extends CommandWithTarget {
   final int frequency;
 
   @override
-  final String kind = 'scroll';
+  String get kind => 'scroll';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -76,9 +79,12 @@ class Scroll extends CommandWithTarget {
 
 /// The result of a [Scroll] command.
 class ScrollResult extends Result {
+  /// Creates a [ScrollResult].
+  const ScrollResult();
+
   /// Deserializes this result from JSON.
   static ScrollResult fromJson(Map<String, dynamic> json) {
-    return ScrollResult();
+    return const ScrollResult();
   }
 
   @override
@@ -106,7 +112,7 @@ class ScrollIntoView extends CommandWithTarget {
   final double alignment;
 
   @override
-  final String kind = 'scrollIntoView';
+  String get kind => 'scrollIntoView';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
diff --git a/packages/flutter_driver/lib/src/common/health.dart b/packages/flutter_driver/lib/src/common/health.dart
index 9441fa68ce2..e7144f9461b 100644
--- a/packages/flutter_driver/lib/src/common/health.dart
+++ b/packages/flutter_driver/lib/src/common/health.dart
@@ -8,13 +8,13 @@ import 'message.dart';
 /// A Flutter Driver command that requests an application health check.
 class GetHealth extends Command {
   /// Create a health check command.
-  GetHealth({ Duration timeout }) : super(timeout: timeout);
+  const GetHealth({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   GetHealth.deserialize(Map<String, String> json) : super.deserialize(json);
 
   @override
-  final String kind = 'get_health';
+  String get kind => 'get_health';
 }
 
 /// A description of application state.
@@ -33,7 +33,7 @@ final EnumIndex<HealthStatus> _healthStatusIndex =
 /// [FlutterDriver.checkHealth] test.
 class Health extends Result {
   /// Creates a [Health] object with the given [status].
-  Health(this.status)
+  const Health(this.status)
     : assert(status != null);
 
   /// The status represented by this object.
diff --git a/packages/flutter_driver/lib/src/common/message.dart b/packages/flutter_driver/lib/src/common/message.dart
index 87bc19f1254..98e8645049d 100644
--- a/packages/flutter_driver/lib/src/common/message.dart
+++ b/packages/flutter_driver/lib/src/common/message.dart
@@ -47,6 +47,9 @@ abstract class Command {
 /// An object sent from a Flutter application back to the Flutter Driver in
 /// response to a command.
 abstract class Result {
+  /// A const constructor to allow subclasses to be const.
+  const Result();
+
   /// Serializes this message to a JSON map.
   Map<String, dynamic> toJson();
 }
diff --git a/packages/flutter_driver/lib/src/common/render_tree.dart b/packages/flutter_driver/lib/src/common/render_tree.dart
index 6bd827ed029..89afc12d86d 100644
--- a/packages/flutter_driver/lib/src/common/render_tree.dart
+++ b/packages/flutter_driver/lib/src/common/render_tree.dart
@@ -7,20 +7,20 @@ import 'message.dart';
 /// A Flutter Driver command that requests a string representation of the render tree.
 class GetRenderTree extends Command {
   /// Create a command to request a string representation of the render tree.
-  GetRenderTree({ Duration timeout }) : super(timeout: timeout);
+  const GetRenderTree({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   GetRenderTree.deserialize(Map<String, String> json) : super.deserialize(json);
 
   @override
-  final String kind = 'get_render_tree';
+  String get kind => 'get_render_tree';
 }
 
 /// A string representation of the render tree, the result of a
 /// [FlutterDriver.getRenderTree] method.
 class RenderTree extends Result {
   /// Creates a [RenderTree] object with the given string representation.
-  RenderTree(this.tree);
+  const RenderTree(this.tree);
 
   /// String representation of the render tree.
   final String tree;
diff --git a/packages/flutter_driver/lib/src/common/request_data.dart b/packages/flutter_driver/lib/src/common/request_data.dart
index d6d64e2777c..609de372946 100644
--- a/packages/flutter_driver/lib/src/common/request_data.dart
+++ b/packages/flutter_driver/lib/src/common/request_data.dart
@@ -8,7 +8,7 @@ import 'message.dart';
 /// string response.
 class RequestData extends Command {
   /// Create a command that sends a message.
-  RequestData(this.message, { Duration timeout }) : super(timeout: timeout);
+  const RequestData(this.message, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   RequestData.deserialize(Map<String, String> params)
@@ -19,7 +19,7 @@ class RequestData extends Command {
   final String message;
 
   @override
-  final String kind = 'request_data';
+  String get kind => 'request_data';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -30,7 +30,7 @@ class RequestData extends Command {
 /// The result of the [RequestData] command.
 class RequestDataResult extends Result {
   /// Creates a result with the given [message].
-  RequestDataResult(this.message);
+  const RequestDataResult(this.message);
 
   /// The text extracted by the [RequestData] command.
   final String message;
diff --git a/packages/flutter_driver/lib/src/common/semantics.dart b/packages/flutter_driver/lib/src/common/semantics.dart
index d44c42089c2..cf80e7787ee 100644
--- a/packages/flutter_driver/lib/src/common/semantics.dart
+++ b/packages/flutter_driver/lib/src/common/semantics.dart
@@ -7,7 +7,7 @@ import 'message.dart';
 /// A Flutter Driver command that enables or disables semantics.
 class SetSemantics extends Command {
   /// Creates a command that enables or disables semantics.
-  SetSemantics(this.enabled, { Duration timeout }) : super(timeout: timeout);
+  const SetSemantics(this.enabled, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   SetSemantics.deserialize(Map<String, String> params)
@@ -18,7 +18,7 @@ class SetSemantics extends Command {
   final bool enabled;
 
   @override
-  final String kind = 'set_semantics';
+  String get kind => 'set_semantics';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -29,7 +29,7 @@ class SetSemantics extends Command {
 /// The result of a [SetSemantics] command.
 class SetSemanticsResult extends Result {
   /// Create a result with the given [changedState].
-  SetSemanticsResult(this.changedState);
+  const SetSemanticsResult(this.changedState);
 
   /// Whether the [SetSemantics] command actually changed the state that the
   /// application was in.
diff --git a/packages/flutter_driver/lib/src/common/text.dart b/packages/flutter_driver/lib/src/common/text.dart
index b5ee236beec..c8f91d510f4 100644
--- a/packages/flutter_driver/lib/src/common/text.dart
+++ b/packages/flutter_driver/lib/src/common/text.dart
@@ -14,13 +14,13 @@ class GetText extends CommandWithTarget {
   GetText.deserialize(Map<String, dynamic> json) : super.deserialize(json);
 
   @override
-  final String kind = 'get_text';
+  String get kind => 'get_text';
 }
 
 /// The result of the [GetText] command.
 class GetTextResult extends Result {
   /// Creates a result with the given [text].
-  GetTextResult(this.text);
+  const GetTextResult(this.text);
 
   /// The text extracted by the [GetText] command.
   final String text;
@@ -39,7 +39,7 @@ class GetTextResult extends Result {
 /// A Flutter Driver command that enters text into the currently focused widget.
 class EnterText extends Command {
   /// Creates a command that enters text into the currently focused widget.
-  EnterText(this.text, { Duration timeout }) : super(timeout: timeout);
+  const EnterText(this.text, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   EnterText.deserialize(Map<String, dynamic> json)
@@ -50,7 +50,7 @@ class EnterText extends Command {
   final String text;
 
   @override
-  final String kind = 'enter_text';
+  String get kind => 'enter_text';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -61,11 +61,11 @@ class EnterText extends Command {
 /// The result of the [EnterText] command.
 class EnterTextResult extends Result {
   /// Creates a successful result of entering the text.
-  EnterTextResult();
+  const EnterTextResult();
 
   /// Deserializes the result from JSON.
   static EnterTextResult fromJson(Map<String, dynamic> json) {
-    return EnterTextResult();
+    return const EnterTextResult();
   }
 
   @override
@@ -75,7 +75,7 @@ class EnterTextResult extends Result {
 /// A Flutter Driver command that enables and disables text entry emulation.
 class SetTextEntryEmulation extends Command {
   /// Creates a command that enables and disables text entry emulation.
-  SetTextEntryEmulation(this.enabled, { Duration timeout }) : super(timeout: timeout);
+  const SetTextEntryEmulation(this.enabled, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   SetTextEntryEmulation.deserialize(Map<String, dynamic> json)
@@ -86,7 +86,7 @@ class SetTextEntryEmulation extends Command {
   final bool enabled;
 
   @override
-  final String kind = 'set_text_entry_emulation';
+  String get kind => 'set_text_entry_emulation';
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
@@ -97,11 +97,11 @@ class SetTextEntryEmulation extends Command {
 /// The result of the [SetTextEntryEmulation] command.
 class SetTextEntryEmulationResult extends Result {
   /// Creates a successful result.
-  SetTextEntryEmulationResult();
+  const SetTextEntryEmulationResult();
 
   /// Deserializes the result from JSON.
   static SetTextEntryEmulationResult fromJson(Map<String, dynamic> json) {
-    return SetTextEntryEmulationResult();
+    return const SetTextEntryEmulationResult();
   }
 
   @override
diff --git a/packages/flutter_driver/lib/src/driver/driver.dart b/packages/flutter_driver/lib/src/driver/driver.dart
index 7071c4ac731..585d8ae0c66 100644
--- a/packages/flutter_driver/lib/src/driver/driver.dart
+++ b/packages/flutter_driver/lib/src/driver/driver.dart
@@ -1016,7 +1016,7 @@ class CommonFinders {
   SerializableFinder byType(String type) => ByType(type);
 
   /// Finds the back button on a Material or Cupertino page's scaffold.
-  SerializableFinder pageBack() => PageBack();
+  SerializableFinder pageBack() => const PageBack();
 }
 
 /// An immutable 2D floating-point offset used by Flutter Driver.
diff --git a/packages/flutter_driver/lib/src/extension/extension.dart b/packages/flutter_driver/lib/src/extension/extension.dart
index 2c9c62e4b7a..c7afd09ec85 100644
--- a/packages/flutter_driver/lib/src/extension/extension.dart
+++ b/packages/flutter_driver/lib/src/extension/extension.dart
@@ -205,7 +205,7 @@ class FlutterDriverExtension {
     };
   }
 
-  Future<Health> _getHealth(Command command) async => Health(HealthStatus.ok);
+  Future<Health> _getHealth(Command command) async => const Health(HealthStatus.ok);
 
   Future<RenderTree> _getRenderTree(Command command) async {
     return RenderTree(RendererBinding.instance?.renderView?.toStringDeep());
@@ -325,19 +325,19 @@ class FlutterDriverExtension {
       _createFinder(tapCommand.finder).hitTestable()
     );
     await _prober.tap(computedFinder);
-    return TapResult();
+    return const TapResult();
   }
 
   Future<WaitForResult> _waitFor(Command command) async {
     final WaitFor waitForCommand = command;
     await _waitForElement(_createFinder(waitForCommand.finder));
-    return WaitForResult();
+    return const WaitForResult();
   }
 
   Future<WaitForAbsentResult> _waitForAbsent(Command command) async {
     final WaitForAbsent waitForAbsentCommand = command;
     await _waitForAbsentElement(_createFinder(waitForAbsentCommand.finder));
-    return WaitForAbsentResult();
+    return const WaitForAbsentResult();
   }
 
   Future<Result> _waitUntilNoTransientCallbacks(Command command) async {
@@ -409,14 +409,14 @@ class FlutterDriverExtension {
     }
     _prober.binding.dispatchEvent(pointer.up(), hitTest);
 
-    return ScrollResult();
+    return const ScrollResult();
   }
 
   Future<ScrollResult> _scrollIntoView(Command command) async {
     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 ScrollResult();
+    return const ScrollResult();
   }
 
   Future<GetTextResult> _getText(Command command) async {
@@ -434,7 +434,7 @@ class FlutterDriverExtension {
     } else {
       _testTextInput.unregister();
     }
-    return SetTextEntryEmulationResult();
+    return const SetTextEntryEmulationResult();
   }
 
   Future<EnterTextResult> _enterText(Command command) async {
@@ -444,7 +444,7 @@ class FlutterDriverExtension {
     }
     final EnterText enterTextCommand = command;
     _testTextInput.enterText(enterTextCommand.text);
-    return EnterTextResult();
+    return const EnterTextResult();
   }
 
   Future<RequestDataResult> _requestData(Command command) async {
@@ -455,7 +455,7 @@ class FlutterDriverExtension {
   Future<SetFrameSyncResult> _setFrameSync(Command command) async {
     final SetFrameSync setFrameSyncCommand = command;
     _frameSync = setFrameSyncCommand.enabled;
-    return SetFrameSyncResult();
+    return const SetFrameSyncResult();
   }
 
   SemanticsHandle _semantics;
diff --git a/packages/flutter_driver/test/src/extension_test.dart b/packages/flutter_driver/test/src/extension_test.dart
index 519100dd7cd..6e139f16edf 100644
--- a/packages/flutter_driver/test/src/extension_test.dart
+++ b/packages/flutter_driver/test/src/extension_test.dart
@@ -24,7 +24,7 @@ void main() {
     });
 
     testWidgets('returns immediately when transient callback queue is empty', (WidgetTester tester) async {
-      extension.call(WaitUntilNoTransientCallbacks().serialize())
+      extension.call(const WaitUntilNoTransientCallbacks().serialize())
         .then<void>(expectAsync1((Map<String, dynamic> r) {
           result = r;
         }));
@@ -44,7 +44,7 @@ void main() {
         // Intentionally blank. We only care about existence of a callback.
       });
 
-      extension.call(WaitUntilNoTransientCallbacks().serialize())
+      extension.call(const WaitUntilNoTransientCallbacks().serialize())
         .then<void>(expectAsync1((Map<String, dynamic> r) {
           result = r;
         }));
@@ -66,7 +66,7 @@ void main() {
 
     testWidgets('handler', (WidgetTester tester) async {
       expect(log, isEmpty);
-      final dynamic result = RequestDataResult.fromJson((await extension.call(RequestData('hello').serialize()))['response']);
+      final dynamic result = RequestDataResult.fromJson((await extension.call(const RequestData('hello').serialize()))['response']);
       expect(log, <String>['hello']);
       expect(result.message, '1');
     });
@@ -83,7 +83,7 @@ void main() {
       await tester.pumpWidget(
         const Text('hello', textDirection: TextDirection.ltr));
 
-      final Map<String, Object> arguments = GetSemanticsId(ByText('hello')).serialize();
+      final Map<String, Object> arguments = GetSemanticsId(const ByText('hello')).serialize();
       final GetSemanticsIdResult result = GetSemanticsIdResult.fromJson((await extension.call(arguments))['response']);
 
       expect(result.id, 1);
@@ -94,7 +94,7 @@ void main() {
       await tester.pumpWidget(
         const Text('hello', textDirection: TextDirection.ltr));
 
-      final Map<String, Object> arguments = GetSemanticsId(ByText('hello')).serialize();
+      final Map<String, Object> arguments = GetSemanticsId(const ByText('hello')).serialize();
       final Map<String, Object> response = await extension.call(arguments);
 
       expect(response['isError'], true);
@@ -113,7 +113,7 @@ void main() {
         ),
       );
 
-      final Map<String, Object> arguments = GetSemanticsId(ByText('hello')).serialize();
+      final Map<String, Object> arguments = GetSemanticsId(const ByText('hello')).serialize();
       final Map<String, Object> response = await extension.call(arguments);
 
       expect(response['isError'], true);