M3 snackbar [re-land] (#116218)

* Add M2 defaults and template skeleton

* add MaterialStateColor functionality to ActionTextColor (issue #110402)

* Add M2 defaults and template skeleton

* updated material 3 tokens

* Updated snackbar demo

* add theme tests

* add gen defaults

* formatting

* more whitespace fixes

* add widget type

* update docs

* code review changes

* Add line overflow functionality

* whitespace fixes

* update M3 animation

* whitespace fixes

* add insetPadding param

* Modifed icon parameter to showCloseIcon

* white space fixes

* test fixes

* rename iconColor to closeIconColor

* debug test fix

* de-britishification

* g3fix

* g3fix

* debug test fix

dev/tools/gen_defaults/bin/gen_defaults.dart

@@ -44,6 +44,7 @@ import 'package:gen_defaults/progress_indicator_template.dart';
 import 'package:gen_defaults/radio_template.dart';
 import 'package:gen_defaults/segmented_button_template.dart';
 import 'package:gen_defaults/slider_template.dart';
+import 'package:gen_defaults/snackbar_template.dart';
 import 'package:gen_defaults/surface_tint.dart';
 import 'package:gen_defaults/switch_template.dart';
 import 'package:gen_defaults/tabs_template.dart';
@@ -162,6 +163,7 @@ Future<void> main(List<String> args) async {
   ProgressIndicatorTemplate('ProgressIndicator', '$materialLib/progress_indicator.dart', tokens).updateFile();
   RadioTemplate('Radio<T>', '$materialLib/radio.dart', tokens).updateFile();
   SegmentedButtonTemplate('SegmentedButton', '$materialLib/segmented_button.dart', tokens).updateFile();
+  SnackbarTemplate('md.comp.snackbar', 'Snackbar', '$materialLib/snack_bar.dart', tokens).updateFile();
   SliderTemplate('md.comp.slider', 'Slider', '$materialLib/slider.dart', tokens).updateFile();
   SurfaceTintTemplate('SurfaceTint', '$materialLib/elevation_overlay.dart', tokens).updateFile();
   SwitchTemplate('Switch', '$materialLib/switch.dart', tokens).updateFile();

dev/tools/gen_defaults/lib/snackbar_template.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'template.dart';
+
+class SnackbarTemplate extends TokenTemplate {
+  const SnackbarTemplate(
+      this.tokenGroup, super.blockName, super.fileName, super.tokens, {
+        super.colorSchemePrefix = '_colors.'
+  });
+
+  final String tokenGroup;
+
+  @override
+  String generate() => '''
+class _${blockName}DefaultsM3 extends SnackBarThemeData {
+    _${blockName}DefaultsM3(this.context);
+
+  final BuildContext context;
+  late final ThemeData _theme = Theme.of(context);
+
+  late final ColorScheme _colors = _theme.colorScheme;
+
+  @override
+  Color get backgroundColor => ${componentColor("$tokenGroup.container")};
+
+  @override
+  Color get actionTextColor =>  MaterialStateColor.resolveWith((Set<MaterialState> states) {
+    if (states.contains(MaterialState.disabled)) {
+      return ${componentColor("$tokenGroup.action.pressed.label-text")};
+    }
+    if (states.contains(MaterialState.pressed)) {
+      return ${componentColor("$tokenGroup.action.pressed.label-text")};
+    }
+    if (states.contains(MaterialState.hovered)) {
+      return ${componentColor("$tokenGroup.action.hover.label-text")};
+    }
+    if (states.contains(MaterialState.focused)) {
+      return ${componentColor("$tokenGroup.action.focus.label-text")};
+    }
+    return ${componentColor("$tokenGroup.action.label-text")};
+  });
+
+  @override
+  Color get disabledActionTextColor =>
+    ${componentColor("$tokenGroup.action.pressed.label-text")};
+
+
+  @override
+  TextStyle get contentTextStyle =>
+    ${textStyle("$tokenGroup.supporting-text")}!.copyWith
+      (color:  ${componentColor("$tokenGroup.supporting-text")},
+    );
+
+  @override
+  double get elevation => ${elevation("$tokenGroup.container")};
+
+  @override
+  ShapeBorder get shape => ${shape("$tokenGroup.container")};
+
+  @override
+  SnackBarBehavior get behavior => SnackBarBehavior.fixed;
+
+  @override
+  EdgeInsets get insetPadding => const EdgeInsets.fromLTRB(15.0, 5.0, 15.0, 10.0);
+
+  @override
+  bool get showCloseIcon => false;
+
+  @override
+  Color get iconColor => _colors.onInverseSurface;
+  }
+
+''';
+}

examples/api/lib/material/snack_bar/snack_bar.2.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// Flutter code sample for [SnackBar] with Material 3 specifications.
+
+import 'package:flutter/material.dart';
+
+void main() => runApp(const MyApp());
+
+// A Material 3 [SnackBar] demonstrating an optional icon, in either floating
+// or fixed format.
+class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+
+  static const String _title = 'Flutter Code Sample';
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: _title,
+      theme: ThemeData(useMaterial3: true),
+      home: Scaffold(
+        appBar: AppBar(title: const Text(_title)),
+        body: const Center(
+          child: SnackBarExample(),
+        ),
+      ),
+    );
+  }
+}
+
+class SnackBarExample extends StatefulWidget {
+  const SnackBarExample({super.key});
+
+  @override
+  State<SnackBarExample> createState() => _SnackBarExampleState();
+}
+
+class _SnackBarExampleState extends State<SnackBarExample> {
+  SnackBarBehavior? _snackBarBehavior = SnackBarBehavior.floating;
+  bool _withIcon = true;
+  bool _withAction = true;
+  bool _multiLine = false;
+  bool _longActionLabel = false;
+
+  Padding _configRow(List<Widget> children) => Padding(
+      padding: const EdgeInsets.all(8.0), child: Row(children: children));
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(padding: const EdgeInsets.only(left: 50.0), child: Column(
+      children: <Widget>[
+        _configRow(<Widget>[
+          Text('Snack Bar configuration',
+              style: Theme.of(context).textTheme.bodyLarge),
+        ]),
+        _configRow(
+          <Widget>[
+            const Text('Fixed'),
+            Radio<SnackBarBehavior>(
+              value: SnackBarBehavior.fixed,
+              groupValue: _snackBarBehavior,
+              onChanged: (SnackBarBehavior? value) {
+                setState(() {
+                  _snackBarBehavior = value;
+                });
+              },
+            ),
+            const Text('Floating'),
+            Radio<SnackBarBehavior>(
+              value: SnackBarBehavior.floating,
+              groupValue: _snackBarBehavior,
+              onChanged: (SnackBarBehavior? value) {
+                setState(() {
+                  _snackBarBehavior = value;
+                });
+              },
+            ),
+          ],
+        ),
+        _configRow(
+          <Widget>[
+            const Text('Include Icon '),
+            Switch(
+              value: _withIcon,
+              onChanged: (bool value) {
+                setState(() {
+                  _withIcon = !_withIcon;
+                });
+              },
+            ),
+          ],
+        ),
+        _configRow(
+          <Widget>[
+            const Text('Include Action '),
+            Switch(
+              value: _withAction,
+              onChanged: (bool value) {
+                setState(() {
+                  _withAction = !_withAction;
+                });
+              },
+            ),
+            const SizedBox(width: 16.0),
+            const Text('Long Action Label '),
+            Switch(
+              value: _longActionLabel,
+              onChanged: !_withAction
+                  ? null
+                  : (bool value) {
+                      setState(() {
+                        _longActionLabel = !_longActionLabel;
+                      });
+                    },
+            ),
+          ],
+        ),
+        _configRow(
+          <Widget>[
+            const Text('Multi Line Text'),
+            Switch(
+              value: _multiLine,
+              onChanged: _snackBarBehavior == SnackBarBehavior.fixed ? null : (bool value) {
+                setState(() {
+                  _multiLine = !_multiLine;
+                });
+              },
+            ),
+          ],
+        ),
+        const SizedBox(height: 16.0),
+        ElevatedButton(
+          child: const Text('Show Snackbar'),
+          onPressed: () {
+            ScaffoldMessenger.of(context).showSnackBar(_snackBar());
+          }
+        ),
+      ],
+    ),
+  );
+}
+
+  SnackBar _snackBar() {
+    final SnackBarAction? action = _withAction
+        ? SnackBarAction(
+            label: _longActionLabel ? 'Long Action Text' : 'Action',
+            onPressed: () {
+              // Code to execute.
+            },
+          )
+        : null;
+    final double? width =
+        _snackBarBehavior == SnackBarBehavior.floating && _multiLine ? 400.0 : null;
+    final String label = _multiLine
+        ? 'A Snack Bar with quite a lot of text which spans across multiple lines'
+        : 'Single Line Snack Bar';
+    return SnackBar(
+      content: Text(label),
+      showCloseIcon: _withIcon,
+      width: width,
+      behavior: _snackBarBehavior,
+      action: action,
+      duration: const Duration(seconds: 3),
+    );
+  }
+}

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

@@ -61,6 +61,9 @@ class SnackBarThemeData with Diagnosticable {
     this.shape,
     this.behavior,
     this.width,
+    this.insetPadding,
+    this.showCloseIcon,
+    this.closeIconColor,
   })  : assert(elevation == null || elevation >= 0.0),
         assert(
             width == null ||
@@ -115,6 +118,21 @@ class SnackBarThemeData with Diagnosticable {
   /// [SnackBarBehavior.floating].
   final double? width;
 
+  /// Overrides the default value for [SnackBar.margin].
+  ///
+  /// This value is only used when [behavior] is [SnackBarBehavior.floating].
+  final EdgeInsets? insetPadding;
+
+  /// Overrides the default value for [SnackBar.showCloseIcon].
+  ///
+  /// Whether to show an optional "Close" icon.
+  final bool? showCloseIcon;
+
+  /// Overrides the default value for [SnackBar.closeIconColor].
+  ///
+  /// This value is only used if [showCloseIcon] is true.
+  final Color? closeIconColor;
+
   /// Creates a copy of this object with the given fields replaced with the
   /// new values.
   SnackBarThemeData copyWith({
@@ -126,6 +144,9 @@ class SnackBarThemeData with Diagnosticable {
     ShapeBorder? shape,
     SnackBarBehavior? behavior,
     double? width,
+    EdgeInsets? insetPadding,
+    bool? showCloseIcon,
+    Color? closeIconColor,
   }) {
     return SnackBarThemeData(
       backgroundColor: backgroundColor ?? this.backgroundColor,
@@ -136,6 +157,9 @@ class SnackBarThemeData with Diagnosticable {
       shape: shape ?? this.shape,
       behavior: behavior ?? this.behavior,
       width: width ?? this.width,
+      insetPadding: insetPadding ?? this.insetPadding,
+      showCloseIcon: showCloseIcon ?? this.showCloseIcon,
+      closeIconColor: closeIconColor ?? this.closeIconColor,
     );
   }
 
@@ -155,6 +179,8 @@ class SnackBarThemeData with Diagnosticable {
       shape: ShapeBorder.lerp(a?.shape, b?.shape, t),
       behavior: t < 0.5 ? a?.behavior : b?.behavior,
       width: lerpDouble(a?.width, b?.width, t),
+      insetPadding: EdgeInsets.lerp(a?.insetPadding, b?.insetPadding, t),
+      closeIconColor: Color.lerp(a?.closeIconColor, b?.closeIconColor, t),
     );
   }
 
@@ -168,6 +194,9 @@ class SnackBarThemeData with Diagnosticable {
         shape,
         behavior,
         width,
+        insetPadding,
+        showCloseIcon,
+        closeIconColor,
       );
 
   @override
@@ -186,7 +215,10 @@ class SnackBarThemeData with Diagnosticable {
         && other.elevation == elevation
         && other.shape == shape
         && other.behavior == behavior
-        && other.width == width;
+        && other.width == width
+        && other.insetPadding == insetPadding
+        && other.showCloseIcon == showCloseIcon
+        && other.closeIconColor == closeIconColor;
   }
 
   @override
@@ -200,5 +232,8 @@ class SnackBarThemeData with Diagnosticable {
     properties.add(DiagnosticsProperty<ShapeBorder>('shape', shape, defaultValue: null));
     properties.add(DiagnosticsProperty<SnackBarBehavior>('behavior', behavior, defaultValue: null));
     properties.add(DoubleProperty('width', width, defaultValue: null));
+    properties.add(DiagnosticsProperty<EdgeInsets>('insetPadding', insetPadding, defaultValue: null));
+    properties.add(DiagnosticsProperty<bool>('showCloseIcon', showCloseIcon, defaultValue: null));
+    properties.add(ColorProperty('closeIconColor', closeIconColor, defaultValue: null));
   }
 }

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

@@ -1339,6 +1339,7 @@ class ThemeData with Diagnosticable {
   ///   * Navigation rail: [NavigationRail]
   ///   * Progress indicators: [CircularProgressIndicator], [LinearProgressIndicator]
   ///   * Radio button: [Radio]
+  ///   * Snack bar: [SnackBar]
   ///   * Slider: [Slider]
   ///   * Switch: [Switch]
   ///   * Tabs: [TabBar]

packages/flutter/test/material/debug_test.dart

@@ -316,6 +316,24 @@ void main() {
       '     TextButtonTheme\n'
       '     Padding\n'
       '     Row\n'
+      '     Column\n'
+      '     _SingleChildViewport\n'
+      '     IgnorePointer-[GlobalKey#d48e8]\n'
+      '     Semantics\n'
+      '     Listener\n'
+      '     _GestureSemantics\n'
+      '     RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#0c3e0]\n'
+      '     Listener\n'
+      '     _ScrollableScope\n'
+      '     _ScrollSemantics-[GlobalKey#349b8]\n'
+      '     NotificationListener<ScrollMetricsNotification>\n'
+      '     RepaintBoundary\n'
+      '     CustomPaint\n'
+      '     RepaintBoundary\n'
+      '     NotificationListener<ScrollNotification>\n'
+      '     GlowingOverscrollIndicator\n'
+      '     Scrollable\n'
+      '     SingleChildScrollView\n'
       '     Padding\n'
       '     MediaQuery\n'
       '     Padding\n'

packages/flutter/test/material/snack_bar_test.dart

@@ -1276,10 +1276,6 @@ void main() {
     await tester.pumpAndSettle();
 
     expect(tester.getSemantics(find.text('snack')), matchesSemantics(
-      isLiveRegion: true,
-      hasDismissAction: true,
-      hasScrollDownAction: true,
-      hasScrollUpAction: true,
       label: 'snack',
       textDirection: TextDirection.ltr,
     ));
@@ -2340,7 +2336,146 @@ void main() {
     await expectLater(find.byType(MaterialApp), matchesGoldenFile('snack_bar.goldenTest.backdropFilter.png'));
   });
 
-  testWidgets('ScaffoldMessenger will alert for snackbars that cannot be presented', (WidgetTester tester) async {
+  testWidgets('Floating snackbar can display optional icon', (WidgetTester tester) async {
+    await tester.pumpWidget(const MaterialApp(
+      home: Scaffold(
+        bottomSheet: SizedBox(
+          width: 200,
+          height: 50,
+          child: ColoredBox(
+            color: Colors.pink,
+          ),
+        ),
+      ),
+    ));
+
+    final ScaffoldMessengerState scaffoldMessengerState = tester.state(find.byType(ScaffoldMessenger));
+    scaffoldMessengerState.showSnackBar(
+      SnackBar(
+        content: const Text('Feeling snackish'),
+        duration: const Duration(seconds: 2),
+        action: SnackBarAction(label: 'ACTION', onPressed: () {}),
+        behavior: SnackBarBehavior.floating,
+        showCloseIcon: true,
+      ),
+    );
+    await tester.pumpAndSettle(); // Have the SnackBar fully animate out.
+
+    await expectLater(
+        find.byType(MaterialApp),
+        matchesGoldenFile(
+            'snack_bar.goldenTest.floatingWithActionWithIcon.png'));
+  });
+
+  testWidgets('Fixed width snackbar can display optional icon', (WidgetTester tester) async {
+    await tester.pumpWidget(const MaterialApp(
+      home: Scaffold(
+        bottomSheet: SizedBox(
+          width: 200,
+          height: 50,
+          child: ColoredBox(
+            color: Colors.pink,
+          ),
+        ),
+      ),
+    ));
+
+    final ScaffoldMessengerState scaffoldMessengerState = tester.state(find.byType(ScaffoldMessenger));
+    scaffoldMessengerState.showSnackBar(SnackBar(
+      content: const Text('Go get a snack'),
+      duration: const Duration(seconds: 2),
+      action: SnackBarAction(label: 'ACTION', onPressed: () {}),
+      showCloseIcon: true,
+      behavior: SnackBarBehavior.fixed,
+    ));
+    await tester.pumpAndSettle(); // Have the SnackBar fully animate out.
+
+    await expectLater(find.byType(MaterialApp), matchesGoldenFile('snack_bar.goldenTest.fixedWithActionWithIcon.png'));
+  });
+
+    testWidgets('Fixed snackbar can display optional icon without action', (WidgetTester tester) async {
+    await tester.pumpWidget(const MaterialApp(
+      home: Scaffold(
+        bottomSheet: SizedBox(
+          width: 200,
+          height: 50,
+          child: ColoredBox(
+            color: Colors.pink,
+          ),
+        ),
+      ),
+    ));
+
+    final ScaffoldMessengerState scaffoldMessengerState = tester.state(find.byType(ScaffoldMessenger));
+    scaffoldMessengerState.showSnackBar(
+     const SnackBar(
+        content:  Text('I wonder if there are snacks nearby?'),
+        duration:  Duration(seconds: 2),
+        behavior: SnackBarBehavior.fixed,
+        showCloseIcon: true,
+      ),
+    );
+    await tester.pumpAndSettle(); // Have the SnackBar fully animate out.
+
+    await expectLater(find.byType(MaterialApp), matchesGoldenFile('snack_bar.goldenTest.fixedWithIcon.png'));
+  });
+
+  testWidgets(
+      'Floating width snackbar can display optional icon without action', (WidgetTester tester) async {
+    await tester.pumpWidget(const MaterialApp(
+      home: Scaffold(
+        bottomSheet: SizedBox(
+          width: 200,
+          height: 50,
+          child: ColoredBox(
+            color: Colors.pink,
+          ),
+        ),
+      ),
+    ));
+
+    final ScaffoldMessengerState scaffoldMessengerState = tester.state(find.byType(ScaffoldMessenger));
+    scaffoldMessengerState.showSnackBar(const SnackBar(
+      content: Text('Must go get a snack!'),
+      duration: Duration(seconds: 2),
+      showCloseIcon: true,
+      behavior: SnackBarBehavior.floating,
+    ));
+    await tester.pumpAndSettle(); // Have the SnackBar fully animate out.
+
+    await expectLater(find.byType(MaterialApp),
+        matchesGoldenFile('snack_bar.goldenTest.floatingWithIcon.png'));
+  });
+
+  testWidgets('Fixed multi-line snackbar with icon is aligned correctly', (WidgetTester tester) async {
+    await tester.pumpWidget(const MaterialApp(
+      home: Scaffold(
+        bottomSheet: SizedBox(
+          width: 200,
+          height: 50,
+          child: ColoredBox(
+            color: Colors.pink,
+          ),
+        ),
+      ),
+    ));
+
+    final ScaffoldMessengerState scaffoldMessengerState = tester.state(find.byType(ScaffoldMessenger));
+    scaffoldMessengerState.showSnackBar(const SnackBar(
+      content: Text(
+          'This is a really long snackbar message. So long, it spans across more than one line!'),
+      duration: Duration(seconds: 2),
+      showCloseIcon: true,
+      behavior: SnackBarBehavior.floating,
+    ));
+    await tester.pumpAndSettle(); // Have the SnackBar fully animate out.
+
+    await expectLater(find.byType(MaterialApp),
+        matchesGoldenFile('snack_bar.goldenTest.multiLineWithIcon.png'));
+  });
+
+  testWidgets(
+      'ScaffoldMessenger will alert for snackbars that cannot be presented', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/103004
     await tester.pumpWidget(const MaterialApp(
       home: Center(),

packages/flutter/test/material/snack_bar_theme_test.dart

@@ -22,6 +22,9 @@ void main() {
     expect(snackBarTheme.shape, null);
     expect(snackBarTheme.behavior, null);
     expect(snackBarTheme.width, null);
+    expect(snackBarTheme.insetPadding, null);
+    expect(snackBarTheme.showCloseIcon, null);
+    expect(snackBarTheme.closeIconColor, null);
   });
 
   test(
@@ -59,6 +62,9 @@ void main() {
       shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(2.0))),
       behavior: SnackBarBehavior.floating,
       width: 400.0,
+      insetPadding: EdgeInsets.all(10.0),
+      showCloseIcon: false,
+      closeIconColor: Color(0xFF0000AA),
     ).debugFillProperties(builder);
 
     final List<String> description = builder.properties
@@ -75,6 +81,9 @@ void main() {
       'shape: RoundedRectangleBorder(BorderSide(width: 0.0, style: none), BorderRadius.circular(2.0))',
       'behavior: SnackBarBehavior.floating',
       'width: 400.0',
+      'insetPadding: EdgeInsets.all(10.0)',
+      'showCloseIcon: false',
+      'closeIconColor: Color(0xff0000aa)',
     ]);
   });
 
@@ -115,7 +124,7 @@ void main() {
   testWidgets('SnackBar uses values from SnackBarThemeData', (WidgetTester tester) async {
     const String text = 'I am a snack bar.';
     const String action = 'ACTION';
-    final SnackBarThemeData snackBarTheme = _snackBarTheme();
+    final SnackBarThemeData snackBarTheme = _snackBarTheme(showCloseIcon: true);
 
     await tester.pumpWidget(MaterialApp(
       theme: ThemeData(snackBarTheme: snackBarTheme),
@@ -144,12 +153,14 @@ void main() {
     final Material material = _getSnackBarMaterial(tester);
     final RenderParagraph button = _getSnackBarActionTextRenderObject(tester, action);
     final RenderParagraph content = _getSnackBarTextRenderObject(tester, text);
+    final Icon icon = _getSnackBarIcon(tester);
 
     expect(content.text.style, snackBarTheme.contentTextStyle);
     expect(material.color, snackBarTheme.backgroundColor);
     expect(material.elevation, snackBarTheme.elevation);
     expect(material.shape, snackBarTheme.shape);
     expect(button.text.style!.color, snackBarTheme.actionTextColor);
+    expect(icon.icon, Icons.close);
   });
 
   testWidgets('SnackBar widget properties take priority over theme', (WidgetTester tester) async {
@@ -163,7 +174,7 @@ void main() {
     const double snackBarWidth = 400.0;
 
     await tester.pumpWidget(MaterialApp(
-      theme: ThemeData(snackBarTheme: _snackBarTheme()),
+      theme: ThemeData(snackBarTheme: _snackBarTheme(showCloseIcon: true)),
       home: Scaffold(
         body: Builder(
           builder: (BuildContext context) {
@@ -182,6 +193,7 @@ void main() {
                     label: action,
                     onPressed: () {},
                   ),
+                  showCloseIcon: false,
                 ));
               },
               child: const Text('X'),
@@ -204,6 +216,7 @@ void main() {
     expect(material.elevation, elevation);
     expect(material.shape, shape);
     expect(button.text.style!.color, textColor);
+    expect(_getSnackBarIconFinder(tester), findsNothing);
     // Assert width.
     final Offset snackBarBottomLeft = tester.getBottomLeft(materialFinder.first);
     final Offset snackBarBottomRight = tester.getBottomRight(materialFinder.first);
@@ -214,8 +227,7 @@ void main() {
   testWidgets('SnackBar theme behavior is correct for floating', (WidgetTester tester) async {
     await tester.pumpWidget(MaterialApp(
       theme: ThemeData(
-        snackBarTheme: const SnackBarThemeData(behavior: SnackBarBehavior.floating),
-      ),
+        snackBarTheme: const SnackBarThemeData(behavior: SnackBarBehavior.floating)),
       home: Scaffold(
         floatingActionButton: FloatingActionButton(
           child: const Icon(Icons.send),
@@ -389,13 +401,14 @@ void main() {
   });
 }
 
-SnackBarThemeData _snackBarTheme() {
-  return const SnackBarThemeData(
+SnackBarThemeData _snackBarTheme({bool? showCloseIcon}) {
+  return SnackBarThemeData(
     backgroundColor: Colors.orange,
     actionTextColor: Colors.green,
-    contentTextStyle: TextStyle(color: Colors.blue),
+    contentTextStyle: const TextStyle(color: Colors.blue),
     elevation: 12.0,
-    shape: BeveledRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(12))),
+    showCloseIcon: showCloseIcon,
+    shape: const BeveledRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(12))),
   );
 }
 
@@ -409,7 +422,6 @@ Finder _getSnackBarMaterialFinder(WidgetTester tester) {
   return find.descendant(
     of: find.byType(SnackBar),
     matching: find.byType(Material),
-
   );
 }
 
@@ -420,6 +432,17 @@ RenderParagraph _getSnackBarActionTextRenderObject(WidgetTester tester, String t
   ));
 }
 
+Icon _getSnackBarIcon(WidgetTester tester) {
+  return tester.widget<Icon>(_getSnackBarIconFinder(tester));
+}
+
+Finder _getSnackBarIconFinder(WidgetTester tester) {
+  return find.descendant(
+    of: find.byType(SnackBar),
+    matching: find.byIcon(Icons.close),
+  );
+}
+
 RenderParagraph _getSnackBarTextRenderObject(WidgetTester tester, String text) {
   return tester.renderObject(find.descendant(
     of: find.byType(SnackBar),