Migrate some widget tests to NNBD (#67776)

packages/flutter/test/widgets/dismissible_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter/gestures.dart' show DragStartBehavior;
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
@@ -12,15 +10,15 @@ import 'package:flutter_test/flutter_test.dart';
 const double itemExtent = 100.0;
 Axis scrollDirection = Axis.vertical;
 DismissDirection dismissDirection = DismissDirection.horizontal;
-DismissDirection reportedDismissDirection;
+late DismissDirection reportedDismissDirection;
 List<int> dismissedItems = <int>[];
-Widget background;
+Widget? background;
 const double crossAxisEndOffset = 0.5;
 
 Widget buildTest({
-  double startToEndThreshold,
+  double? startToEndThreshold,
   TextDirection textDirection = TextDirection.ltr,
-  Future<bool> Function(BuildContext context, DismissDirection direction) confirmDismiss,
+  Future<bool> Function(BuildContext context, DismissDirection direction)? confirmDismiss,
 }) {
   return Directionality(
     textDirection: textDirection,
@@ -73,9 +71,9 @@ Widget buildTest({
   );
 }
 
-typedef DismissMethod = Future<void> Function(WidgetTester tester, Finder finder, { @required AxisDirection gestureDirection });
+typedef DismissMethod = Future<void> Function(WidgetTester tester, Finder finder, { required AxisDirection gestureDirection });
 
-Future<void> dismissElement(WidgetTester tester, Finder finder, { @required AxisDirection gestureDirection }) async {
+Future<void> dismissElement(WidgetTester tester, Finder finder, { required AxisDirection gestureDirection }) async {
   Offset downLocation;
   Offset upLocation;
   switch (gestureDirection) {
@@ -110,7 +108,7 @@ Future<void> dismissElement(WidgetTester tester, Finder finder, { @required Axis
   await gesture.up();
 }
 
-Future<void> flingElement(WidgetTester tester, Finder finder, { @required AxisDirection gestureDirection, double initialOffsetFactor = 0.0 }) async {
+Future<void> flingElement(WidgetTester tester, Finder finder, { required AxisDirection gestureDirection, double initialOffsetFactor = 0.0 }) async {
   Offset delta;
   switch (gestureDirection) {
     case AxisDirection.left:
@@ -131,7 +129,7 @@ Future<void> flingElement(WidgetTester tester, Finder finder, { @required AxisDi
   await tester.fling(finder, delta, 1000.0, initialOffset: delta * initialOffsetFactor);
 }
 
-Future<void> flingElementFromZero(WidgetTester tester, Finder finder, { @required AxisDirection gestureDirection }) async {
+Future<void> flingElementFromZero(WidgetTester tester, Finder finder, { required AxisDirection gestureDirection }) async {
   // This is a special case where we drag in one direction, then fling back so
   // that at the point of release, we're at exactly the point at which we
   // started, but with velocity. This is needed to check a boundary condition
@@ -142,7 +140,7 @@ Future<void> flingElementFromZero(WidgetTester tester, Finder finder, { @require
 Future<void> dismissItem(
   WidgetTester tester,
   int item, {
-  @required AxisDirection gestureDirection,
+  required AxisDirection gestureDirection,
   DismissMethod mechanism = dismissElement,
 }) async {
   assert(gestureDirection != null);
@@ -161,7 +159,7 @@ Future<void> dismissItem(
 Future<void> checkFlingItemBeforeMovementEnd(
   WidgetTester tester,
   int item, {
-  @required AxisDirection gestureDirection,
+  required AxisDirection gestureDirection,
   DismissMethod mechanism = rollbackElement,
 }) async {
   assert(gestureDirection != null);
@@ -177,7 +175,7 @@ Future<void> checkFlingItemBeforeMovementEnd(
 Future<void> checkFlingItemAfterMovement(
   WidgetTester tester,
   int item, {
-  @required AxisDirection gestureDirection,
+  required AxisDirection gestureDirection,
   DismissMethod mechanism = rollbackElement,
 }) async {
   assert(gestureDirection != null);
@@ -190,7 +188,7 @@ Future<void> checkFlingItemAfterMovement(
   await tester.pump(const Duration(milliseconds: 300));
 }
 
-Future<void> rollbackElement(WidgetTester tester, Finder finder, { @required AxisDirection gestureDirection, double initialOffsetFactor = 0.0 }) async {
+Future<void> rollbackElement(WidgetTester tester, Finder finder, { required AxisDirection gestureDirection, double initialOffsetFactor = 0.0 }) async {
   Offset delta;
   switch (gestureDirection) {
     case AxisDirection.left:
@@ -210,7 +208,7 @@ Future<void> rollbackElement(WidgetTester tester, Finder finder, { @required Axi
 }
 
 class Test1215DismissibleWidget extends StatelessWidget {
-  const Test1215DismissibleWidget(this.text, { Key key }) : super(key: key);
+  const Test1215DismissibleWidget(this.text, { Key? key }) : super(key: key);
 
   final String text;
 
@@ -679,9 +677,9 @@ void main() {
   testWidgets('confirmDismiss returns values: true, false, null', (WidgetTester tester) async {
     scrollDirection = Axis.vertical;
     dismissDirection = DismissDirection.horizontal;
-    DismissDirection confirmDismissDirection;
+    late DismissDirection confirmDismissDirection;
 
-    Widget buildFrame(bool confirmDismissValue) {
+    Widget buildFrame(bool? confirmDismissValue) {
       return buildTest(
         confirmDismiss: (BuildContext context, DismissDirection dismissDirection) {
           confirmDismissDirection = dismissDirection;
@@ -802,7 +800,7 @@ void main() {
   testWidgets('Dismissible.behavior should behave correctly during hit testing', (WidgetTester tester) async {
     bool didReceivePointerDown = false;
 
-    Widget buildStack({Widget child}) {
+    Widget buildStack({required Widget child}) {
       return Directionality(
         textDirection: TextDirection.ltr,
         child: Stack(

packages/flutter/test/widgets/disposable_build_context_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 
 import 'package:flutter/widgets.dart';
@@ -14,7 +12,7 @@ void main() {
     final GlobalKey<TestWidgetState> key = GlobalKey<TestWidgetState>();
     await tester.pumpWidget(TestWidget(key));
 
-    final TestWidgetState state = key.currentState;
+    final TestWidgetState state = key.currentState!;
     expect(state.mounted, true);
 
     final DisposableBuildContext context = DisposableBuildContext(state);
@@ -35,7 +33,7 @@ void main() {
 }
 
 class TestWidget extends StatefulWidget {
-  const TestWidget(Key key) : super(key: key);
+  const TestWidget(Key? key) : super(key: key);
 
   @override
   State<TestWidget> createState() => TestWidgetState();

packages/flutter/test/widgets/dispose_ancestor_lookup_test.dart

@@ -2,15 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
 
 typedef TestCallback = void Function(BuildContext context);
 
 class TestWidget extends StatefulWidget {
-  const TestWidget(this.callback, { Key key }) : super(key: key);
+  const TestWidget(this.callback, { Key? key }) : super(key: key);
 
   final TestCallback callback;
 

packages/flutter/test/widgets/draggable_scrollable_sheet_test.dart

@@ -2,22 +2,20 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
-  Widget _boilerplate(VoidCallback onButtonPressed, {
+  Widget _boilerplate(VoidCallback? onButtonPressed, {
     int itemCount = 100,
     double initialChildSize = .5,
     double maxChildSize = 1.0,
     double minChildSize = .25,
-    double itemExtent,
-    Key containerKey,
-    NotificationListenerCallback<ScrollNotification> onScrollNotification,
+    double? itemExtent,
+    Key? containerKey,
+    NotificationListenerCallback<ScrollNotification>? onScrollNotification,
   }) {
     return Directionality(
       textDirection: TextDirection.ltr,

packages/flutter/test/widgets/drawer_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:ui';
 
 import 'package:flutter_test/flutter_test.dart';
@@ -19,7 +17,7 @@ void main() {
 
   testWidgets('Drawer control test', (WidgetTester tester) async {
     final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
-    BuildContext savedContext;
+    late BuildContext savedContext;
     await tester.pumpWidget(
       MaterialApp(
         home: Builder(
@@ -36,7 +34,7 @@ void main() {
     );
     await tester.pump(); // no effect
     expect(find.text('drawer'), findsNothing);
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump(); // drawer should be starting to animate in
     expect(find.text('drawer'), findsOneWidget);
     await tester.pump(const Duration(seconds: 1)); // animation done
@@ -61,7 +59,7 @@ void main() {
     );
     await tester.pump(); // no effect
     expect(find.text('drawer'), findsNothing);
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump(); // drawer should be starting to animate in
     expect(find.text('drawer'), findsOneWidget);
     await tester.pump(const Duration(seconds: 1)); // animation done
@@ -120,7 +118,7 @@ void main() {
     logs.clear();
 
     // When drawer is open, hover is uninteractable
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump(const Duration(seconds: 1)); // animation done
     expect(find.text('drawer'), findsOneWidget);
 
@@ -174,7 +172,7 @@ void main() {
       ),
     );
     expect(find.text('drawer'), findsNothing);
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump(); // drawer should be starting to animate in
     expect(find.text('drawer'), findsOneWidget);
     await tester.pump(const Duration(seconds: 1)); // animation done
@@ -228,7 +226,7 @@ void main() {
       ),
     );
     expect(find.text('drawer'), findsNothing);
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump(); // drawer should be starting to animate in
     expect(find.text('drawer'), findsOneWidget);
     await tester.pump(const Duration(seconds: 1)); // animation done
@@ -290,7 +288,7 @@ void main() {
     );
 
     // Open the drawer.
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump(); // drawer should be starting to animate in
     expect(find.text('drawer'), findsOneWidget);
 
@@ -324,7 +322,7 @@ void main() {
     );
 
     // Open the drawer.
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump(const Duration(milliseconds: 100));
 
     expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.tap]));
@@ -352,7 +350,7 @@ void main() {
     );
 
     // Open the drawer.
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump(const Duration(milliseconds: 100));
 
     expect(semantics, isNot(includesNodeWith(actions: <SemanticsAction>[SemanticsAction.tap])));
@@ -380,7 +378,7 @@ void main() {
     );
 
     // Open the drawer.
-    scaffoldKey.currentState.openDrawer();
+    scaffoldKey.currentState!.openDrawer();
     await tester.pump();
     await tester.pump(const Duration(milliseconds: 100));
 

packages/flutter/test/widgets/dual_transition_builder_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
@@ -23,7 +21,7 @@ void main() {
         forwardBuilder: (
           BuildContext context,
           Animation<double> animation,
-          Widget child,
+          Widget? child,
         ) {
           return ScaleTransition(
             scale: animation,
@@ -33,7 +31,7 @@ void main() {
         reverseBuilder: (
           BuildContext context,
           Animation<double> animation,
-          Widget child,
+          Widget? child,
         ) {
           return FadeTransition(
             opacity: Tween<double>(begin: 1.0, end: 0.0).animate(animation),
@@ -93,7 +91,7 @@ void main() {
           forwardBuilder: (
             BuildContext context,
             Animation<double> animation,
-            Widget child,
+            Widget? child,
           ) {
             return ScaleTransition(
               scale: animation,
@@ -103,7 +101,7 @@ void main() {
           reverseBuilder: (
             BuildContext context,
             Animation<double> animation,
-            Widget child,
+            Widget? child,
           ) {
             return FadeTransition(
               opacity: Tween<double>(begin: 1.0, end: 0.0).animate(animation),
@@ -155,7 +153,7 @@ void main() {
         forwardBuilder: (
           BuildContext context,
           Animation<double> animation,
-          Widget child,
+          Widget? child,
         ) {
           return ScaleTransition(
             scale: animation,
@@ -165,7 +163,7 @@ void main() {
         reverseBuilder: (
           BuildContext context,
           Animation<double> animation,
-          Widget child,
+          Widget? child,
         ) {
           return FadeTransition(
             opacity: Tween<double>(begin: 1.0, end: 0.0).animate(animation),
@@ -221,7 +219,7 @@ void main() {
         forwardBuilder: (
           BuildContext context,
           Animation<double> animation,
-          Widget child,
+          Widget? child,
         ) {
           return ScaleTransition(
             scale: animation,
@@ -231,7 +229,7 @@ void main() {
         reverseBuilder: (
           BuildContext context,
           Animation<double> animation,
-          Widget child,
+          Widget? child,
         ) {
           return FadeTransition(
             opacity: Tween<double>(begin: 1.0, end: 0.0).animate(animation),
@@ -286,7 +284,7 @@ double _getOpacity(WidgetTester tester) {
 }
 
 class _StatefulTestWidget extends StatefulWidget {
-  const _StatefulTestWidget({Key key, this.name}) : super(key: key);
+  const _StatefulTestWidget({Key? key, required this.name}) : super(key: key);
 
   final String name;
 

packages/flutter/test/widgets/editable_text_cursor_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -46,13 +44,13 @@ void main() {
     final EditableText editableText = tester.firstWidget(find.byType(EditableText));
     expect(editableText.cursorWidth, 10.0);
     expect(editableText.cursorHeight, 10.0);
-    expect(editableText.cursorRadius.x, 2.0);
+    expect(editableText.cursorRadius!.x, 2.0);
   });
 
   testWidgets('cursor layout has correct width', (WidgetTester tester) async {
     final GlobalKey<EditableTextState> editableTextKey = GlobalKey<EditableTextState>();
 
-    String changedValue;
+    late String changedValue;
     final Widget widget = MaterialApp(
       home: RepaintBoundary(
         key: const ValueKey<int>(1),
@@ -61,7 +59,7 @@ void main() {
           key: editableTextKey,
           controller: TextEditingController(),
           focusNode: FocusNode(),
-          style: Typography.material2018(platform: TargetPlatform.android).black.subtitle1,
+          style: Typography.material2018(platform: TargetPlatform.android).black.subtitle1!,
           cursorColor: Colors.blue,
           selectionControls: materialTextSelectionControls,
           keyboardType: TextInputType.text,
@@ -103,7 +101,7 @@ void main() {
   testWidgets('cursor layout has correct radius', (WidgetTester tester) async {
     final GlobalKey<EditableTextState> editableTextKey = GlobalKey<EditableTextState>();
 
-    String changedValue;
+    late String changedValue;
     final Widget widget = MaterialApp(
       home: RepaintBoundary(
         key: const ValueKey<int>(1),
@@ -112,7 +110,7 @@ void main() {
           key: editableTextKey,
           controller: TextEditingController(),
           focusNode: FocusNode(),
-          style: Typography.material2018(platform: TargetPlatform.android).black.subtitle1,
+          style: Typography.material2018(platform: TargetPlatform.android).black.subtitle1!,
           cursorColor: Colors.blue,
           selectionControls: materialTextSelectionControls,
           keyboardType: TextInputType.text,
@@ -167,43 +165,43 @@ void main() {
     final EditableTextState editableTextState = tester.firstState(find.byType(EditableText));
     final RenderEditable renderEditable = editableTextState.renderEditable;
 
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
 
     // Trigger initial timer. When focusing the first time, the cursor shows
     // for slightly longer than the average on time.
     await tester.pump();
     await tester.pump(const Duration(milliseconds: 200));
     // Start timing standard cursor show period.
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rrect(color: const Color(0xff2196f3)));
 
     await tester.pump(const Duration(milliseconds: 500));
     // Start to animate the cursor away.
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rrect(color: const Color(0xff2196f3)));
 
     await tester.pump(const Duration(milliseconds: 100));
-    expect(renderEditable.cursorColor.alpha, 110);
+    expect(renderEditable.cursorColor!.alpha, 110);
     expect(renderEditable, paints..rrect(color: const Color(0x6e2196f3)));
 
     await tester.pump(const Duration(milliseconds: 100));
-    expect(renderEditable.cursorColor.alpha, 16);
+    expect(renderEditable.cursorColor!.alpha, 16);
     expect(renderEditable, paints..rrect(color: const Color(0x102196f3)));
 
     await tester.pump(const Duration(milliseconds: 100));
-    expect(renderEditable.cursorColor.alpha, 0);
+    expect(renderEditable.cursorColor!.alpha, 0);
     // Don't try to draw the cursor.
     expect(renderEditable, paintsExactlyCountTimes(#drawRRect, 0));
 
     // Wait some more while the cursor is gone. It'll trigger the cursor to
     // start animating in again.
     await tester.pump(const Duration(milliseconds: 300));
-    expect(renderEditable.cursorColor.alpha, 0);
+    expect(renderEditable.cursorColor!.alpha, 0);
     expect(renderEditable, paintsExactlyCountTimes(#drawRRect, 0));
 
     await tester.pump(const Duration(milliseconds: 50));
     // Cursor starts coming back.
-    expect(renderEditable.cursorColor.alpha, 79);
+    expect(renderEditable.cursorColor!.alpha, 79);
     expect(renderEditable, paints..rrect(color: const Color(0x4f2196f3)));
   }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS,  TargetPlatform.macOS }));
 
@@ -225,25 +223,25 @@ void main() {
     final RenderEditable renderEditable = editableTextState.renderEditable;
 
     await tester.pump();
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rect(color: defaultCursorColor));
 
     // Android cursor goes from exactly on to exactly off on the 500ms dot.
     await tester.pump(const Duration(milliseconds: 499));
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rect(color: defaultCursorColor));
 
     await tester.pump(const Duration(milliseconds: 1));
-    expect(renderEditable.cursorColor.alpha, 0);
+    expect(renderEditable.cursorColor!.alpha, 0);
     // Don't try to draw the cursor.
     expect(renderEditable, paintsExactlyCountTimes(#drawRect, 0));
 
     await tester.pump(const Duration(milliseconds: 500));
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rect(color: defaultCursorColor));
 
     await tester.pump(const Duration(milliseconds: 500));
-    expect(renderEditable.cursorColor.alpha, 0);
+    expect(renderEditable.cursorColor!.alpha, 0);
     expect(renderEditable, paintsExactlyCountTimes(#drawRect, 0));
   });
 
@@ -265,21 +263,21 @@ void main() {
     final EditableTextState editableTextState = tester.firstState(find.byType(EditableText));
     final RenderEditable renderEditable = editableTextState.renderEditable;
 
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
 
     await tester.pump();
     await tester.pump(const Duration(milliseconds: 200));
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rrect(color: defaultCursorColor));
 
     // Cursor draw never changes.
     await tester.pump(const Duration(milliseconds: 200));
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rrect(color: defaultCursorColor));
 
     // No more transient calls.
     await tester.pumpAndSettle();
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rrect(color: defaultCursorColor));
 
     EditableText.debugDeterministicCursor = false;
@@ -304,21 +302,21 @@ void main() {
     final RenderEditable renderEditable = editableTextState.renderEditable;
 
     await tester.pump();
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rect(color: defaultCursorColor));
 
     await tester.pump(const Duration(milliseconds: 500));
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rect(color: defaultCursorColor));
 
     // Cursor draw never changes.
     await tester.pump(const Duration(milliseconds: 500));
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rect(color: defaultCursorColor));
 
     // No more transient calls.
     await tester.pumpAndSettle();
-    expect(renderEditable.cursorColor.alpha, 255);
+    expect(renderEditable.cursorColor!.alpha, 255);
     expect(renderEditable, paints..rect(color: defaultCursorColor));
 
     EditableText.debugDeterministicCursor = false;
@@ -716,7 +714,7 @@ void main() {
   testWidgets('cursor layout', (WidgetTester tester) async {
     final GlobalKey<EditableTextState> editableTextKey = GlobalKey<EditableTextState>();
 
-    String changedValue;
+    late String changedValue;
     final Widget widget = MaterialApp(
       home: RepaintBoundary(
         key: const ValueKey<int>(1),
@@ -728,7 +726,7 @@ void main() {
               key: editableTextKey,
               controller: TextEditingController(),
               focusNode: FocusNode(),
-              style: Typography.material2018(platform: TargetPlatform.iOS).black.subtitle1,
+              style: Typography.material2018(platform: TargetPlatform.iOS).black.subtitle1!,
               cursorColor: Colors.blue,
               selectionControls: materialTextSelectionControls,
               keyboardType: TextInputType.text,
@@ -772,7 +770,7 @@ void main() {
   testWidgets('cursor layout has correct height', (WidgetTester tester) async {
     final GlobalKey<EditableTextState> editableTextKey = GlobalKey<EditableTextState>();
 
-    String changedValue;
+    late String changedValue;
     final Widget widget = MaterialApp(
       home: RepaintBoundary(
         key: const ValueKey<int>(1),
@@ -784,7 +782,7 @@ void main() {
               key: editableTextKey,
               controller: TextEditingController(),
               focusNode: FocusNode(),
-              style: Typography.material2018(platform: TargetPlatform.iOS).black.subtitle1,
+              style: Typography.material2018(platform: TargetPlatform.iOS).black.subtitle1!,
               cursorColor: Colors.blue,
               selectionControls: materialTextSelectionControls,
               keyboardType: TextInputType.text,

packages/flutter/test/widgets/editable_text_show_on_screen_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
@@ -12,9 +10,9 @@ import 'package:flutter/services.dart';
 
 class _TestSliverPersistentHeaderDelegate extends SliverPersistentHeaderDelegate {
   _TestSliverPersistentHeaderDelegate({
-    this.minExtent,
-    this.maxExtent,
-    this.child,
+    required this.minExtent,
+    required this.maxExtent,
+    required this.child,
     this.vsync = const TestVSync(),
     this.showOnScreenConfiguration = const PersistentHeaderShowOnScreenConfiguration(),
   });
@@ -28,7 +26,7 @@ class _TestSliverPersistentHeaderDelegate extends SliverPersistentHeaderDelegate
   final double minExtent;
 
   @override
-  final TickerProvider vsync;
+  final TickerProvider? vsync;
 
   @override
   final PersistentHeaderShowOnScreenConfiguration showOnScreenConfiguration;
@@ -496,13 +494,13 @@ void main() {
 }
 
 class NoImplicitScrollPhysics extends AlwaysScrollableScrollPhysics {
-  const NoImplicitScrollPhysics({ ScrollPhysics parent }) : super(parent: parent);
+  const NoImplicitScrollPhysics({ ScrollPhysics? parent }) : super(parent: parent);
 
   @override
   bool get allowImplicitScrolling => false;
 
   @override
-  NoImplicitScrollPhysics applyTo(ScrollPhysics ancestor) {
+  NoImplicitScrollPhysics applyTo(ScrollPhysics? ancestor) {
     return NoImplicitScrollPhysics(parent: buildParent(ancestor));
   }
 }