Add Linux and Windows target platforms (#51519)

This PR adds the linux and windows target platform enum values, along with automatically setting the defaultTargetPlatform to the appropriate value on those platforms.

Fixes #31366

dev/integration_tests/flutter_driver_screenshot_test/lib/main.dart

@@ -83,10 +83,14 @@ class _MyHomePageState extends State<_MyHomePage> {
             return (await deviceInfo.androidInfo).model;
           case TargetPlatform.fuchsia:
             return 'fuchsia';
-          default:
+          case TargetPlatform.macOS:
+          case TargetPlatform.linux:
+          case TargetPlatform.windows:
             return 'unsupported';
+            break;
         }
-        break;
+        assert(false, 'Unhandled Theme target platform ${Theme.of(context).platform}.');
+        return 'unsupported';
     }
     return 'unknown message: "$message"';
   }

dev/manual_tests/lib/actions.dart

@@ -2,24 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(const MaterialApp(
     title: 'Actions Demo',
     home: FocusDemo(),

dev/manual_tests/lib/animated_icons.dart

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
-
-import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
 class AnimatedIconsTestApp extends StatelessWidget {
@@ -108,16 +105,4 @@ class IconSample {
   final String description;
 }
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
-void main() {
-  _enablePlatformOverrideForDesktop();
-  runApp(AnimatedIconsTestApp());
-}
+void main() => runApp(AnimatedIconsTestApp());

dev/manual_tests/lib/density.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:io';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/scheduler.dart' show timeDilation;
@@ -24,19 +23,7 @@ final Map<int, Color> m2SwatchColors = <int, Color>{
 };
 final MaterialColor m2Swatch = MaterialColor(m2SwatchColors[500].value, m2SwatchColors);
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
-void main() {
-  _enablePlatformOverrideForDesktop();
-  runApp(MyApp());
-}
+void main() => runApp(MyApp());
 
 class MyApp extends StatelessWidget {
   static const String _title = 'Density Test';

dev/manual_tests/lib/drag_and_drop.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:flutter/foundation.dart';
@@ -296,17 +295,7 @@ class DragAndDropAppState extends State<DragAndDropApp> {
   }
 }
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(MaterialApp(
     title: 'Drag and Drop Flutter Demo',
     home: DragAndDropApp(),

dev/manual_tests/lib/focus.dart

@@ -2,24 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(const MaterialApp(
     title: 'Focus Demo',
     home: FocusDemo(),

dev/manual_tests/lib/hover.dart

@@ -2,23 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(const MaterialApp(
     title: 'Hover Demo',
     home: HoverDemo(),

dev/manual_tests/lib/main.dart

@@ -2,22 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
-
-import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(const Directionality(
     textDirection: TextDirection.ltr,
     child: Center(

dev/manual_tests/lib/material_arc.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:io';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
@@ -475,17 +474,7 @@ class _AnimationDemoState extends State<AnimationDemo> with TickerProviderStateM
   }
 }
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(const MaterialApp(
     home: AnimationDemo(),
   ));

dev/manual_tests/lib/overlay_geometry.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.
 
-import 'dart:io';
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
@@ -206,17 +204,7 @@ class OverlayGeometryAppState extends State<OverlayGeometryApp> {
   }
 }
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(MaterialApp(
     theme: ThemeData(
       brightness: Brightness.light,

dev/manual_tests/lib/page_view.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.
 
-import 'dart:io';
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
@@ -141,17 +139,7 @@ class PageViewAppState extends State<PageViewApp> {
   }
 }
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(MaterialApp(
     title: 'PageView',
     theme: ThemeData(

dev/manual_tests/lib/raw_keyboard.dart

@@ -2,23 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(MaterialApp(
     title: 'Hardware Key Demo',
     home: Scaffold(

dev/manual_tests/lib/text.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:flutter/foundation.dart';
@@ -12,17 +11,7 @@ import 'package:flutter/scheduler.dart';
 
 int seed = 0;
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-// TODO(gspencergoog): Remove once TargetPlatform includes all desktop platforms.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-
 void main() {
-  _enablePlatformOverrideForDesktop();
   runApp(MaterialApp(
     title: 'Text tester',
     home: const Home(),

examples/flutter_gallery/lib/demo/material/drawer_demo.dart

@@ -62,6 +62,8 @@ class _DrawerDemoState extends State<DrawerDemo> with TickerProviderStateMixin {
     switch (Theme.of(context).platform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return Icons.arrow_back;
       case TargetPlatform.iOS:
       case TargetPlatform.macOS:

examples/flutter_gallery/lib/gallery/options.dart

@@ -413,8 +413,12 @@ class _PlatformItem extends StatelessWidget {
         return 'Fuchsia';
       case TargetPlatform.iOS:
         return 'Cupertino';
+      case TargetPlatform.linux:
+        return 'Material Desktop (linux)';
       case TargetPlatform.macOS:
         return 'Material Desktop (macOS)';
+      case TargetPlatform.windows:
+        return 'Material Desktop (Windows)';
     }
     assert(false);
     return null;

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

@@ -234,7 +234,9 @@ class _CupertinoPickerState extends State<CupertinoPicker> {
         break;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
       case TargetPlatform.macOS:
+      case TargetPlatform.windows:
         hasSuitableHapticHardware = false;
         break;
     }

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

@@ -456,7 +456,9 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
         break;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
       case TargetPlatform.macOS:
+      case TargetPlatform.windows:
         break;
     }
   }

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

@@ -9,14 +9,18 @@ import 'platform.dart' as platform;
 /// The dart:io implementation of [platform.defaultTargetPlatform].
 platform.TargetPlatform get defaultTargetPlatform {
   platform.TargetPlatform result;
-  if (Platform.isIOS) {
-    result = platform.TargetPlatform.iOS;
-  } else if (Platform.isMacOS) {
-    result = platform.TargetPlatform.macOS;
-  } else if (Platform.isAndroid) {
+  if (Platform.isAndroid) {
     result = platform.TargetPlatform.android;
+  } else if (Platform.isIOS) {
+    result = platform.TargetPlatform.iOS;
   } else if (Platform.isFuchsia) {
     result = platform.TargetPlatform.fuchsia;
+  } else if (Platform.isLinux) {
+    result = platform.TargetPlatform.linux;
+  } else if (Platform.isMacOS) {
+    result = platform.TargetPlatform.macOS;
+  } else if (Platform.isWindows) {
+    result = platform.TargetPlatform.windows;
   }
   assert(() {
     if (Platform.environment.containsKey('FLUTTER_TEST'))

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

@@ -161,14 +161,20 @@ abstract class BindingBase {
               case 'android':
                 debugDefaultTargetPlatformOverride = TargetPlatform.android;
                 break;
+              case 'fuchsia':
+                debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
+                break;
               case 'iOS':
                 debugDefaultTargetPlatformOverride = TargetPlatform.iOS;
                 break;
+              case 'linux':
+                debugDefaultTargetPlatformOverride = TargetPlatform.linux;
+                break;
               case 'macOS':
                 debugDefaultTargetPlatformOverride = TargetPlatform.macOS;
                 break;
-              case 'fuchsia':
-                debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
+              case 'windows':
+                debugDefaultTargetPlatformOverride = TargetPlatform.windows;
                 break;
               case 'default':
               default:

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

@@ -45,11 +45,17 @@ enum TargetPlatform {
   /// Fuchsia: <https://fuchsia.googlesource.com/>
   fuchsia,
 
-  /// iOS: <http://www.apple.com/ios/>
+  /// iOS: <https://www.apple.com/ios/>
   iOS,
 
-  /// macOS: <http://www.apple.com/macos>
+  /// Linux: <https://www.linux.org>
+  linux,
+
+  /// macOS: <https://www.apple.com/macos>
   macOS,
+
+  /// Windows: <https://www.windows.com>
+  windows,
 }
 
 /// Override the [defaultTargetPlatform].

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

@@ -548,7 +548,9 @@ class _MaterialScrollBehavior extends ScrollBehavior {
     // the base class as well.
     switch (getPlatform(context)) {
       case TargetPlatform.iOS:
+      case TargetPlatform.linux:
       case TargetPlatform.macOS:
+      case TargetPlatform.windows:
         return child;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:

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

@@ -426,6 +426,8 @@ class AppBar extends StatefulWidget implements PreferredSizeWidget {
     switch (theme.platform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return false;
       case TargetPlatform.iOS:
       case TargetPlatform.macOS:
@@ -516,6 +518,8 @@ class _AppBarState extends State<AppBar> {
       switch (theme.platform) {
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           namesRoute = true;
           break;
         case TargetPlatform.iOS:

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

@@ -32,6 +32,8 @@ class BackButtonIcon extends StatelessWidget {
     switch (platform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return Icons.arrow_back;
       case TargetPlatform.iOS:
       case TargetPlatform.macOS:

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

@@ -339,6 +339,8 @@ class _ModalBottomSheetState<T> extends State<_ModalBottomSheet<T>> {
         return '';
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return localizations.dialogLabel;
     }
     return null;

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

@@ -908,6 +908,8 @@ class _DatePickerDialogState extends State<_DatePickerDialog> {
     switch (Theme.of(context).platform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         HapticFeedback.vibrate();
         break;
       case TargetPlatform.iOS:

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

@@ -464,6 +464,8 @@ class AlertDialog extends StatelessWidget {
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           label = semanticLabel ?? MaterialLocalizations.of(context)?.alertDialogLabel;
       }
     }
@@ -794,6 +796,8 @@ class SimpleDialog extends StatelessWidget {
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           label = semanticLabel ?? MaterialLocalizations.of(context)?.dialogLabel;
       }
     }

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

@@ -182,6 +182,8 @@ class Drawer extends StatelessWidget {
         break;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         label = semanticLabel ?? MaterialLocalizations.of(context)?.drawerLabel;
     }
     return Semantics(
@@ -536,6 +538,8 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
         case TargetPlatform.iOS:
         case TargetPlatform.macOS:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           platformHasBackButton = false;
           break;
       }

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

@@ -99,9 +99,15 @@ class Feedback {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
         return SystemSound.play(SystemSoundType.click);
-      default:
+      case TargetPlatform.iOS:
+      case TargetPlatform.linux:
+      case TargetPlatform.macOS:
+      case TargetPlatform.windows:
         return Future<void>.value();
+        break;
     }
+    assert(false, 'Unhandled TargetPlatform ${_platform(context)}');
+    return Future<void>.value();
   }
 
   /// Wraps a [GestureTapCallback] to provide platform specific feedback for a
@@ -138,9 +144,15 @@ class Feedback {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
         return HapticFeedback.vibrate();
-      default:
+      case TargetPlatform.iOS:
+      case TargetPlatform.linux:
+      case TargetPlatform.macOS:
+      case TargetPlatform.windows:
         return Future<void>.value();
+        break;
     }
+    assert(false, 'Unhandled TargetPlatform ${_platform(context)}');
+    return Future<void>.value();
   }
 
   /// Wraps a [GestureLongPressCallback] to provide platform specific feedback

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

@@ -237,6 +237,8 @@ class _FlexibleSpaceBarState extends State<FlexibleSpaceBar> {
     switch (theme.platform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return false;
       case TargetPlatform.iOS:
       case TargetPlatform.macOS:
@@ -345,8 +347,10 @@ class _FlexibleSpaceBarState extends State<FlexibleSpaceBar> {
             case TargetPlatform.macOS:
               title = widget.title;
               break;
-            case TargetPlatform.fuchsia:
             case TargetPlatform.android:
+            case TargetPlatform.fuchsia:
+            case TargetPlatform.linux:
+            case TargetPlatform.windows:
               title = Semantics(
                 namesRoute: true,
                 child: widget.title,

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

@@ -494,7 +494,9 @@ class PageTransitionsTheme extends Diagnosticable {
   static const Map<TargetPlatform, PageTransitionsBuilder> _defaultBuilders = <TargetPlatform, PageTransitionsBuilder>{
     TargetPlatform.android: FadeUpwardsPageTransitionsBuilder(),
     TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
+    TargetPlatform.linux: FadeUpwardsPageTransitionsBuilder(),
     TargetPlatform.macOS: CupertinoPageTransitionsBuilder(),
+    TargetPlatform.windows: FadeUpwardsPageTransitionsBuilder(),
   };
 
   /// The [PageTransitionsBuilder]s supported by this theme.

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

@@ -837,6 +837,8 @@ Future<T> showMenu<T>({
       break;
     case TargetPlatform.android:
     case TargetPlatform.fuchsia:
+    case TargetPlatform.linux:
+    case TargetPlatform.windows:
       label = semanticLabel ?? MaterialLocalizations.of(context)?.popupMenuLabel;
   }
 
@@ -1096,6 +1098,8 @@ class PopupMenuButtonState<T> extends State<PopupMenuButton<T>> {
     switch (platform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return const Icon(Icons.more_vert);
       case TargetPlatform.iOS:
       case TargetPlatform.macOS:

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

@@ -903,10 +903,14 @@ class _RenderRangeSlider extends RenderBox with RelayoutWhenSystemFontsChangeMix
         return 0.1;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
-      default:
+      case TargetPlatform.linux:
+      case TargetPlatform.macOS:
+      case TargetPlatform.windows:
         // Matches Android implementation of material slider.
         return 0.05;
     }
+    assert(false, 'Unhandled TargetPlatform $_platform');
+    return 0.05;
   }
 
   void _updateLabelPainters() {

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

@@ -2498,6 +2498,8 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
         break;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         break;
     }
 

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

@@ -96,6 +96,8 @@ class _ScrollbarState extends State<Scrollbar> with TickerProviderStateMixin {
         break;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         _themeColor = theme.highlightColor.withOpacity(1.0);
         _textDirection = Directionality.of(context);
         _materialPainter = _buildMaterialScrollbarPainter();

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

@@ -492,6 +492,8 @@ class _SearchPageState<T> extends State<_SearchPage<T>> {
         break;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         routeName = searchFieldLabel;
     }
 

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

@@ -78,6 +78,8 @@ class _SelectableTextSelectionGestureDetectorBuilder extends TextSelectionGestur
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           renderEditable.selectWordsInRange(
             from: details.globalPosition - details.offsetFromOrigin,
             to: details.globalPosition,
@@ -99,6 +101,8 @@ class _SelectableTextSelectionGestureDetectorBuilder extends TextSelectionGestur
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           renderEditable.selectPosition(cause: SelectionChangedCause.tap);
           break;
       }
@@ -120,6 +124,8 @@ class _SelectableTextSelectionGestureDetectorBuilder extends TextSelectionGestur
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           renderEditable.selectWord(cause: SelectionChangedCause.longPress);
           Feedback.forLongPress(_state.context);
           break;
@@ -494,6 +500,8 @@ class _SelectableTextState extends State<SelectableText> with AutomaticKeepAlive
         return;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
       // Do nothing.
     }
   }
@@ -567,6 +575,8 @@ class _SelectableTextState extends State<SelectableText> with AutomaticKeepAlive
 
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         forcePressEnabled = false;
         textSelectionControls = materialTextSelectionControls;
         paintCursorAboveText = false;

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

@@ -502,6 +502,8 @@ class _SliderState extends State<Slider> with TickerProviderStateMixin {
         switch (theme.platform) {
           case TargetPlatform.android:
           case TargetPlatform.fuchsia:
+          case TargetPlatform.linux:
+          case TargetPlatform.windows:
             return _buildMaterialSlider(context);
           case TargetPlatform.iOS:
           case TargetPlatform.macOS:
@@ -892,13 +894,16 @@ class _RenderSlider extends RenderBox with RelayoutWhenSystemFontsChangeMixin {
     switch (_platform) {
       case TargetPlatform.iOS:
       case TargetPlatform.macOS:
-      // Matches iOS implementation of material slider.
+        // Matches iOS implementation of material slider.
         return 0.1;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
-      // Matches Android implementation of material slider.
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
+        // Matches Android implementation of material slider.
         return 0.05;
     }
+    assert(false, 'Unhandled TargetPlatform $_platform');
     return 0.0;
   }
 

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

@@ -352,6 +352,8 @@ class _SwitchState extends State<Switch> with TickerProviderStateMixin {
         switch (theme.platform) {
           case TargetPlatform.android:
           case TargetPlatform.fuchsia:
+          case TargetPlatform.linux:
+          case TargetPlatform.windows:
             return buildMaterialSwitch(context);
           case TargetPlatform.iOS:
           case TargetPlatform.macOS:

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

@@ -69,6 +69,8 @@ class _TextFieldSelectionGestureDetectorBuilder extends TextSelectionGestureDete
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           renderEditable.selectWordsInRange(
             from: details.globalPosition - details.offsetFromOrigin,
             to: details.globalPosition,
@@ -90,6 +92,8 @@ class _TextFieldSelectionGestureDetectorBuilder extends TextSelectionGestureDete
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           renderEditable.selectPosition(cause: SelectionChangedCause.tap);
           break;
       }
@@ -112,6 +116,8 @@ class _TextFieldSelectionGestureDetectorBuilder extends TextSelectionGestureDete
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           renderEditable.selectWord(cause: SelectionChangedCause.longPress);
           Feedback.forLongPress(_state.context);
           break;
@@ -919,6 +925,8 @@ class _TextFieldState extends State<TextField> implements TextSelectionGestureDe
         return;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         // Do nothing.
     }
   }
@@ -980,6 +988,8 @@ class _TextFieldState extends State<TextField> implements TextSelectionGestureDe
 
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         forcePressEnabled = false;
         textSelectionControls = materialTextSelectionControls;
         paintCursorAboveText = false;

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

@@ -206,6 +206,8 @@ class _DayPeriodControl extends StatelessWidget {
     switch (fragmentContext.targetPlatform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         _announceToAccessibility(context, MaterialLocalizations.of(context).anteMeridiemAbbreviation);
         break;
       case TargetPlatform.iOS:
@@ -222,6 +224,8 @@ class _DayPeriodControl extends StatelessWidget {
     switch (fragmentContext.targetPlatform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         _announceToAccessibility(context, MaterialLocalizations.of(context).postMeridiemAbbreviation);
         break;
       case TargetPlatform.iOS:
@@ -1535,6 +1539,8 @@ class _TimePickerDialogState extends State<_TimePickerDialog> {
     switch (Theme.of(context).platform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         _vibrateTimer?.cancel();
         _vibrateTimer = Timer(_kVibrateCommitDelay, () {
           HapticFeedback.vibrate();

packages/flutter/lib/src/rendering/editable.dart

@@ -1732,6 +1732,8 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin {
         return Rect.fromLTWH(0.0, 0.0, cursorWidth, preferredLineHeight + 2);
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return Rect.fromLTWH(0.0, _kCaretHeightOffset, cursorWidth, preferredLineHeight - 2.0 * _kCaretHeightOffset);
     }
     return null;
@@ -1800,6 +1802,8 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin {
           break;
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
           // Override the height to take the full height of the glyph at the TextPosition
           // when not on iOS. iOS has special handling that creates a taller caret.
           // TODO(garyq): See the TODO for _getCaretPrototype.

packages/flutter/lib/src/rendering/view.dart

@@ -255,7 +255,9 @@ class RenderView extends RenderObject with RenderObjectWithChildMixin<RenderBox>
         break;
       case TargetPlatform.fuchsia:
       case TargetPlatform.iOS:
+      case TargetPlatform.linux:
       case TargetPlatform.macOS:
+      case TargetPlatform.windows:
         break;
     }
     // If there are no overlay styles in the UI don't bother updating.

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

@@ -919,6 +919,8 @@ class WidgetsApp extends StatefulWidget {
     switch (defaultTargetPlatform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return _defaultShortcuts;
       case TargetPlatform.macOS:
         return _defaultMacOsShortcuts;

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

@@ -79,6 +79,8 @@ class ModalBarrier extends StatelessWidget {
     switch (defaultTargetPlatform) {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         platformSupportsDismissingBarrier = false;
         break;
       case TargetPlatform.iOS:

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

@@ -35,7 +35,9 @@ class ScrollBehavior {
     // _MaterialScrollBehavior as well.
     switch (getPlatform(context)) {
       case TargetPlatform.iOS:
+      case TargetPlatform.linux:
       case TargetPlatform.macOS:
+      case TargetPlatform.windows:
         return child;
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
@@ -59,6 +61,8 @@ class ScrollBehavior {
         return const BouncingScrollPhysics();
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
         return const ClampingScrollPhysics();
     }
     return null;

packages/flutter/test/foundation/service_extensions_test.dart

@@ -530,11 +530,27 @@ void main() {
     extensionChangedEvent = extensionChangedEvents.last;
     expect(extensionChangedEvent['extension'], 'ext.flutter.platformOverride');
     expect(extensionChangedEvent['value'], 'iOS');
+    result = await hasReassemble(binding.testExtension('platformOverride', <String, String>{'value': 'linux'}));
+    expect(result, <String, String>{'value': 'linux'});
+    expect(binding.reassembled, 7);
+    expect(defaultTargetPlatform, TargetPlatform.linux);
+    expect(extensionChangedEvents.length, 7);
+    extensionChangedEvent = extensionChangedEvents.last;
+    expect(extensionChangedEvent['extension'], 'ext.flutter.platformOverride');
+    expect(extensionChangedEvent['value'], 'linux');
+    result = await hasReassemble(binding.testExtension('platformOverride', <String, String>{'value': 'windows'}));
+    expect(result, <String, String>{'value': 'windows'});
+    expect(binding.reassembled, 8);
+    expect(defaultTargetPlatform, TargetPlatform.windows);
+    expect(extensionChangedEvents.length, 8);
+    extensionChangedEvent = extensionChangedEvents.last;
+    expect(extensionChangedEvent['extension'], 'ext.flutter.platformOverride');
+    expect(extensionChangedEvent['value'], 'windows');
     result = await hasReassemble(binding.testExtension('platformOverride', <String, String>{'value': 'bogus'}));
     expect(result, <String, String>{'value': 'android'});
-    expect(binding.reassembled, 7);
+    expect(binding.reassembled, 9);
     expect(defaultTargetPlatform, TargetPlatform.android);
-    expect(extensionChangedEvents.length, 7);
+    expect(extensionChangedEvents.length, 9);
     extensionChangedEvent = extensionChangedEvents.last;
     expect(extensionChangedEvent['extension'], 'ext.flutter.platformOverride');
     expect(extensionChangedEvent['value'], 'android');

packages/flutter/test/material/back_button_test.dart

@@ -68,7 +68,9 @@ void main() {
   testWidgets('BackButton icon', (WidgetTester tester) async {
     final Key androidKey = UniqueKey();
     final Key iOSKey = UniqueKey();
+    final Key linuxKey = UniqueKey();
     final Key macOSKey = UniqueKey();
+    final Key windowsKey = UniqueKey();
 
     await tester.pumpWidget(
       MaterialApp(
@@ -82,10 +84,18 @@ void main() {
               data: ThemeData(platform: TargetPlatform.iOS),
               child: BackButtonIcon(key: iOSKey),
             ),
+            Theme(
+              data: ThemeData(platform: TargetPlatform.linux),
+              child: BackButtonIcon(key: linuxKey),
+            ),
             Theme(
               data: ThemeData(platform: TargetPlatform.macOS),
               child: BackButtonIcon(key: macOSKey),
             ),
+            Theme(
+              data: ThemeData(platform: TargetPlatform.windows),
+              child: BackButtonIcon(key: windowsKey),
+            ),
           ],
         ),
       ),
@@ -93,10 +103,14 @@ void main() {
 
     final Icon androidIcon = tester.widget(find.descendant(of: find.byKey(androidKey), matching: find.byType(Icon)));
     final Icon iOSIcon = tester.widget(find.descendant(of: find.byKey(iOSKey), matching: find.byType(Icon)));
+    final Icon linuxIcon = tester.widget(find.descendant(of: find.byKey(linuxKey), matching: find.byType(Icon)));
     final Icon macOSIcon = tester.widget(find.descendant(of: find.byKey(macOSKey), matching: find.byType(Icon)));
+    final Icon windowsIcon = tester.widget(find.descendant(of: find.byKey(windowsKey), matching: find.byType(Icon)));
     expect(iOSIcon.icon == androidIcon.icon, isFalse);
+    expect(linuxIcon.icon == androidIcon.icon, isTrue);
     expect(macOSIcon.icon == androidIcon.icon, isFalse);
     expect(macOSIcon.icon == iOSIcon.icon, isTrue);
+    expect(windowsIcon.icon == androidIcon.icon, isTrue);
   });
 
   testWidgets('BackButton color', (WidgetTester tester) async {

packages/flutter/test/material/flexible_space_bar_collapse_mode_test.dart

@@ -47,7 +47,7 @@ void main() {
 
     expect(topBeforeScroll.dy, equals(0.0));
     expect(topAfterScroll.dy, equals(0.0));
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.iOS,  TargetPlatform.macOS }));
+  }, variant: TargetPlatformVariant(TargetPlatform.values.where((TargetPlatform value) => value != TargetPlatform.fuchsia).toSet()));
 
   testWidgets('FlexibleSpaceBar collapse mode pin', (WidgetTester tester) async {
     await tester.pumpWidget(
@@ -85,7 +85,7 @@ void main() {
 
     expect(topBeforeScroll.dy, equals(0.0));
     expect(topAfterScroll.dy, equals(-100.0));
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.iOS,  TargetPlatform.macOS }));
+  }, variant: TargetPlatformVariant(TargetPlatform.values.where((TargetPlatform value) => value != TargetPlatform.fuchsia).toSet()));
 
   testWidgets('FlexibleSpaceBar collapse mode parallax', (WidgetTester tester) async {
     await tester.pumpWidget(
@@ -124,7 +124,7 @@ void main() {
     expect(topBeforeScroll.dy, equals(0.0));
     expect(topAfterScroll.dy, lessThan(10.0));
     expect(topAfterScroll.dy, greaterThan(-50.0));
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.iOS,  TargetPlatform.macOS }));
+  }, variant: TargetPlatformVariant(TargetPlatform.values.where((TargetPlatform value) => value != TargetPlatform.fuchsia).toSet()));
 }
 
 Future<void> slowDrag(WidgetTester tester, Key widget, Offset offset) async {

packages/flutter/test/material/flexible_space_bar_test.dart

@@ -198,7 +198,7 @@ void main() {
     await tester.pumpWidget(buildFrame(TargetPlatform.android, true));
     expect(getTitleBottomLeft(), const Offset(390.0, 0.0));
 
-    // Clear the widget tree to avoid animating between Android and iOS.
+    // Clear the widget tree to avoid animating between platforms.
     await tester.pumpWidget(Container(key: UniqueKey()));
 
     await tester.pumpWidget(buildFrame(TargetPlatform.iOS, null));
@@ -207,7 +207,7 @@ void main() {
     await tester.pumpWidget(buildFrame(TargetPlatform.iOS, false));
     expect(getTitleBottomLeft(), Offset.zero);
 
-    // Clear the widget tree to avoid animating between iOS and macOS.
+    // Clear the widget tree to avoid animating between platforms.
     await tester.pumpWidget(Container(key: UniqueKey()));
 
     await tester.pumpWidget(buildFrame(TargetPlatform.macOS, null));
@@ -215,6 +215,24 @@ void main() {
 
     await tester.pumpWidget(buildFrame(TargetPlatform.macOS, false));
     expect(getTitleBottomLeft(), Offset.zero);
+
+    // Clear the widget tree to avoid animating between platforms.
+    await tester.pumpWidget(Container(key: UniqueKey()));
+
+    await tester.pumpWidget(buildFrame(TargetPlatform.windows, null));
+    expect(getTitleBottomLeft(), Offset.zero);
+
+    await tester.pumpWidget(buildFrame(TargetPlatform.windows, true));
+    expect(getTitleBottomLeft(), const Offset(390.0, 0.0));
+
+    // Clear the widget tree to avoid animating between platforms.
+    await tester.pumpWidget(Container(key: UniqueKey()));
+
+    await tester.pumpWidget(buildFrame(TargetPlatform.linux, null));
+    expect(getTitleBottomLeft(), Offset.zero);
+
+    await tester.pumpWidget(buildFrame(TargetPlatform.linux, true));
+    expect(getTitleBottomLeft(), const Offset(390.0, 0.0));
   }, skip: isBrowser);
 }
 

packages/flutter/test/material/slider_test.dart

@@ -1250,7 +1250,7 @@ void main() {
         ));
 
     semantics.dispose();
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia }));
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
   testWidgets('Slider Semantics', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);
@@ -1497,7 +1497,7 @@ void main() {
       await gesture.up();
     }
 
-    for (final TargetPlatform platform in <TargetPlatform>[TargetPlatform.android, TargetPlatform.fuchsia]) {
+    for (final TargetPlatform platform in <TargetPlatform>[TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows]) {
       value = 0.5;
       await tester.pumpWidget(buildFrame(platform));
       await tester.pumpAndSettle(); // Finish the theme change animation.

packages/flutter/test/material/switch_list_tile_test.dart

@@ -96,7 +96,7 @@ void main() {
       expect(value, isTrue, reason: 'on ${describeEnum(platform)}');
     }
 
-    for (final TargetPlatform platform in <TargetPlatform>[ TargetPlatform.android, TargetPlatform.fuchsia ]) {
+    for (final TargetPlatform platform in <TargetPlatform>[ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows ]) {
       value = false;
       await tester.pumpWidget(buildFrame(platform));
       await tester.pumpAndSettle(); // Finish the theme change animation.

packages/flutter/test/material/switch_test.dart

@@ -623,7 +623,7 @@ void main() {
       expect(value, isTrue, reason: 'on ${describeEnum(platform)}');
     }
 
-    for (final TargetPlatform platform in <TargetPlatform>[ TargetPlatform.android, TargetPlatform.fuchsia ]) {
+    for (final TargetPlatform platform in <TargetPlatform>[ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows ]) {
       value = false;
       await tester.pumpWidget(buildFrame(platform));
       await tester.pumpAndSettle(); // Finish the theme change animation.

packages/flutter/test/material/text_field_test.dart

@@ -663,7 +663,7 @@ void main() {
     expect(find.text('COPY'), findsOneWidget);
     expect(find.text('CUT'), findsNothing);
     expect(find.text('SELECT ALL'), findsNothing);
-  }, skip: isBrowser, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia }));
+  }, skip: isBrowser, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
   testWidgets('cursor layout has correct width', (WidgetTester tester) async {
     EditableText.debugDeterministicCursor = true;
@@ -1125,7 +1125,7 @@ void main() {
       matching: find.byType(Container),
     ));
     expect(container.size, Size.zero);
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia }));
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
   testWidgets('Sawping controllers should update selection', (WidgetTester tester) async {
     TextEditingController controller = TextEditingController(text: 'readonly');
@@ -5662,7 +5662,7 @@ void main() {
 
       // But don't trigger the toolbar.
       expect(find.byType(FlatButton), findsNothing);
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia }));
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
   testWidgets(
     'two slow taps do not trigger a word selection',
@@ -5787,7 +5787,7 @@ void main() {
 
       // Selected text shows 4 toolbar buttons: cut, copy, paste, select all
       expect(find.byType(FlatButton), findsNWidgets(4));
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia }));
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
   testWidgets(
     'double tap on top of cursor also selects word',
@@ -5836,7 +5836,7 @@ void main() {
 
       // Selected text shows 4 toolbar buttons: cut, copy, paste, select all
       expect(find.byType(FlatButton), findsNWidgets(4));
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia }));
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
   testWidgets(
     'double double tap just shows the selection menu',
@@ -6118,7 +6118,7 @@ void main() {
 
       // Collapsed toolbar shows 4 buttons: cut, copy, paste, select all
       expect(find.byType(FlatButton), findsNWidgets(4));
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia }));
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
   testWidgets(
     'long press tap cannot initiate a double tap',
@@ -6496,7 +6496,7 @@ void main() {
     await gesture.up();
     await tester.pump();
     expect(find.byType(FlatButton), findsNothing);
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android,  TargetPlatform.fuchsia }));
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android, TargetPlatform.fuchsia, TargetPlatform.linux, TargetPlatform.windows }));
 
   testWidgets('force press selects word', (WidgetTester tester) async {
     final TextEditingController controller = TextEditingController(

packages/flutter/test/material/typography_test.dart

@@ -16,55 +16,63 @@ void main() {
     }
   });
 
-  test('Typography on Android, Fuchsia defaults to Roboto', () {
+  test('Typography on non-Apple platforms defaults to the correct font', () {
     expect(Typography.material2018(platform: TargetPlatform.android).black.headline6.fontFamily, 'Roboto');
     expect(Typography.material2018(platform: TargetPlatform.fuchsia).black.headline6.fontFamily, 'Roboto');
+    expect(Typography.material2018(platform: TargetPlatform.linux).black.headline6.fontFamily, 'Roboto');
+    expect(Typography.material2018(platform: TargetPlatform.linux).black.headline6.fontFamilyFallback, <String>['Ubuntu', 'Cantarell', 'DejaVu Sans', 'Liberation Sans', 'Arial']);
+    expect(Typography.material2018(platform: TargetPlatform.windows).black.headline6.fontFamily, 'Segoe UI');
+    expect(Typography.material2018(platform: TargetPlatform.android).white.headline6.fontFamily, 'Roboto');
+    expect(Typography.material2018(platform: TargetPlatform.fuchsia).white.headline6.fontFamily, 'Roboto');
+    expect(Typography.material2018(platform: TargetPlatform.linux).white.headline6.fontFamily, 'Roboto');
+    expect(Typography.material2018(platform: TargetPlatform.linux).white.headline6.fontFamilyFallback, <String>['Ubuntu', 'Cantarell', 'DejaVu Sans', 'Liberation Sans', 'Arial']);
+    expect(Typography.material2018(platform: TargetPlatform.windows).white.headline6.fontFamily, 'Segoe UI');
   });
 
   // Ref: https://developer.apple.com/ios/human-interface-guidelines/visual-design/typography/
-  final Matcher isDisplayFont = predicate((TextStyle s) {
+  final Matcher isSanFranciscoDisplayFont = predicate((TextStyle s) {
     return s.fontFamily == '.SF UI Display';
   }, 'Uses SF Display font');
 
-  final Matcher isTextFont = predicate((TextStyle s) {
+  final Matcher isSanFranciscoTextFont = predicate((TextStyle s) {
     return s.fontFamily == '.SF UI Text';
   }, 'Uses SF Text font');
 
   test('Typography on iOS defaults to the correct SF font family based on size', () {
     final Typography typography = Typography.material2018(platform: TargetPlatform.iOS);
     for (final TextTheme textTheme in <TextTheme>[typography.black, typography.white]) {
-      expect(textTheme.headline1, isDisplayFont);
-      expect(textTheme.headline2, isDisplayFont);
-      expect(textTheme.headline3, isDisplayFont);
-      expect(textTheme.headline4, isDisplayFont);
-      expect(textTheme.headline5, isDisplayFont);
-      expect(textTheme.headline6, isDisplayFont);
-      expect(textTheme.subtitle1, isTextFont);
-      expect(textTheme.bodyText1, isTextFont);
-      expect(textTheme.bodyText2, isTextFont);
-      expect(textTheme.caption, isTextFont);
-      expect(textTheme.button, isTextFont);
-      expect(textTheme.subtitle2, isTextFont);
-      expect(textTheme.overline, isTextFont);
+      expect(textTheme.headline1, isSanFranciscoDisplayFont);
+      expect(textTheme.headline2, isSanFranciscoDisplayFont);
+      expect(textTheme.headline3, isSanFranciscoDisplayFont);
+      expect(textTheme.headline4, isSanFranciscoDisplayFont);
+      expect(textTheme.headline5, isSanFranciscoDisplayFont);
+      expect(textTheme.headline6, isSanFranciscoDisplayFont);
+      expect(textTheme.subtitle1, isSanFranciscoTextFont);
+      expect(textTheme.bodyText1, isSanFranciscoTextFont);
+      expect(textTheme.bodyText2, isSanFranciscoTextFont);
+      expect(textTheme.caption, isSanFranciscoTextFont);
+      expect(textTheme.button, isSanFranciscoTextFont);
+      expect(textTheme.subtitle2, isSanFranciscoTextFont);
+      expect(textTheme.overline, isSanFranciscoTextFont);
     }
   });
 
   test('Typography on macOS defaults to the correct SF font family based on size', () {
     final Typography typography = Typography.material2018(platform: TargetPlatform.macOS);
     for (final TextTheme textTheme in <TextTheme>[typography.black, typography.white]) {
-      expect(textTheme.headline1, isDisplayFont);
-      expect(textTheme.headline2, isDisplayFont);
-      expect(textTheme.headline3, isDisplayFont);
-      expect(textTheme.headline4, isDisplayFont);
-      expect(textTheme.headline5, isDisplayFont);
-      expect(textTheme.headline6, isDisplayFont);
-      expect(textTheme.subtitle1, isTextFont);
-      expect(textTheme.bodyText1, isTextFont);
-      expect(textTheme.bodyText2, isTextFont);
-      expect(textTheme.caption, isTextFont);
-      expect(textTheme.button, isTextFont);
-      expect(textTheme.subtitle2, isTextFont);
-      expect(textTheme.overline, isTextFont);
+      expect(textTheme.headline1, isSanFranciscoDisplayFont);
+      expect(textTheme.headline2, isSanFranciscoDisplayFont);
+      expect(textTheme.headline3, isSanFranciscoDisplayFont);
+      expect(textTheme.headline4, isSanFranciscoDisplayFont);
+      expect(textTheme.headline5, isSanFranciscoDisplayFont);
+      expect(textTheme.headline6, isSanFranciscoDisplayFont);
+      expect(textTheme.subtitle1, isSanFranciscoTextFont);
+      expect(textTheme.bodyText1, isSanFranciscoTextFont);
+      expect(textTheme.bodyText2, isSanFranciscoTextFont);
+      expect(textTheme.caption, isSanFranciscoTextFont);
+      expect(textTheme.button, isSanFranciscoTextFont);
+      expect(textTheme.subtitle2, isSanFranciscoTextFont);
+      expect(textTheme.overline, isSanFranciscoTextFont);
     }
   });
 

packages/flutter/test/widgets/drawer_test.dart

@@ -357,7 +357,7 @@ void main() {
     expect(semantics, isNot(includesNodeWith(label: 'Dismiss')));
 
     semantics.dispose();
-  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android }));
+  }, variant: TargetPlatformVariant.only(TargetPlatform.android));
 
   testWidgets('Drawer contains route semantics flags', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);

packages/flutter/test/widgets/scrollable_fling_test.dart

@@ -45,6 +45,22 @@ void main() {
     await tester.pump(const Duration(seconds: 5));
     final double androidResult = getCurrentOffset();
 
+    await pumpTest(tester, TargetPlatform.linux);
+    await tester.fling(find.byType(ListView), const Offset(0.0, -dragOffset), 1000.0);
+    expect(getCurrentOffset(), dragOffset);
+    await tester.pump(); // trigger fling
+    expect(getCurrentOffset(), dragOffset);
+    await tester.pump(const Duration(seconds: 5));
+    final double linuxResult = getCurrentOffset();
+
+    await pumpTest(tester, TargetPlatform.windows);
+    await tester.fling(find.byType(ListView), const Offset(0.0, -dragOffset), 1000.0);
+    expect(getCurrentOffset(), dragOffset);
+    await tester.pump(); // trigger fling
+    expect(getCurrentOffset(), dragOffset);
+    await tester.pump(const Duration(seconds: 5));
+    final double windowsResult = getCurrentOffset();
+
     await pumpTest(tester, TargetPlatform.iOS);
     await tester.fling(find.byType(ListView), const Offset(0.0, -dragOffset), 1000.0);
     // Scroll starts ease into the scroll on iOS.
@@ -65,6 +81,14 @@ void main() {
 
     expect(androidResult, lessThan(iOSResult)); // iOS is slipperier than Android
     expect(androidResult, lessThan(macOSResult)); // macOS is slipperier than Android
+    expect(linuxResult, lessThan(iOSResult)); // iOS is slipperier than Linux
+    expect(linuxResult, lessThan(macOSResult)); // macOS is slipperier than Linux
+    expect(windowsResult, lessThan(iOSResult)); // iOS is slipperier than Windows
+    expect(windowsResult, lessThan(macOSResult)); // macOS is slipperier than Windows
+    expect(windowsResult, equals(androidResult));
+    expect(windowsResult, equals(androidResult));
+    expect(linuxResult, equals(androidResult));
+    expect(linuxResult, equals(androidResult));
   });
 
   testWidgets('fling and tap to stop', (WidgetTester tester) async {

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

@@ -642,9 +642,6 @@ To edit platform code in an IDE see https://flutter.dev/developing-packages/#edi
       'web': web,
       'macos': macos,
       'year': DateTime.now().year,
-      // If a desktop platform is included, add a workaround for #31366.
-      // When Linux and Windows are added, we will need this workaround again.
-      'includeTargetPlatformWorkaround': false,
     };
   }
 

packages/flutter_tools/templates/app/lib/main.dart.tmpl

-{{#includeTargetPlatformWorkaround}}
-import 'dart:io';
-
-import 'package:flutter/foundation.dart';
-{{/includeTargetPlatformWorkaround}}
 import 'package:flutter/material.dart';
 {{#withDriverTest}}
 import 'package:flutter_driver/driver_extension.dart';
@@ -13,39 +8,15 @@ import 'dart:async';
 import 'package:flutter/services.dart';
 import 'package:{{pluginProjectName}}/{{pluginProjectName}}.dart';
 {{/withPluginHook}}
-{{#includeTargetPlatformWorkaround}}
 
-// Sets a platform override for desktop to avoid exceptions. See
-// https://flutter.dev/desktop#target-platform-override for more info.
-void _enablePlatformOverrideForDesktop() {
-  if (!kIsWeb && (Platform.isWindows || Platform.isLinux)) {
-    debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
-  }
-}
-{{/includeTargetPlatformWorkaround}}
-
-{{^withDriverTest}}
-{{^includeTargetPlatformWorkaround}}
-void main() => runApp(MyApp());
-{{/includeTargetPlatformWorkaround}}
-{{#includeTargetPlatformWorkaround}}
 void main() {
-  _enablePlatformOverrideForDesktop();
-  runApp(MyApp());
-}
-{{/includeTargetPlatformWorkaround}}
-{{/withDriverTest}}
 {{#withDriverTest}}
-void main() {
-{{#includeTargetPlatformWorkaround}}
-  _enablePlatformOverrideForDesktop();
-{{/includeTargetPlatformWorkaround}}
   // Enable integration testing with the Flutter Driver extension.
   // See https://flutter.dev/testing/ for more info.
   enableFlutterDriverExtension();
+{{/withDriverTest}}
   runApp(MyApp());
 }
-{{/withDriverTest}}
 
 {{^withPluginHook}}
 class MyApp extends StatelessWidget {