Added M3 demo app (#1189)

* Added M3 demo app

* Changed to use the centralized lint configuration.

* Moved the app at the root level

* Added to CI

* Added app to beta CI and commented app on stable CI file

* Update README.md

* Addressed comments

* fixed comments

* Reverted app name in CI files.

* Added project to the Pub Dependabot config

* Linting pass for current beta channel standards

Co-authored-by: Qun Cheng <quncheng@google.com>
Co-authored-by: Craig Labenz <craig.labenz@gmail.com>

material_3_demo/test/color_screen_test.dart

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+// ignore_for_file: avoid_types_on_closure_parameters
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:material_3_demo/color_palettes_screen.dart';
+import 'package:material_3_demo/main.dart';
+
+import 'component_screen_test.dart';
+
+void main() {
+  testWidgets(
+      'Color palettes screen shows correctly when color icon is clicked '
+      'on NavigationBar', (tester) async {
+    widgetSetup(tester, 449);
+    addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
+    await tester.pumpWidget(const Material3Demo());
+
+    expect(find.text("Light Theme"), findsNothing);
+    expect(find.text("Dark Theme"), findsNothing);
+    expect(find.byType(NavigationBar), findsOneWidget);
+    Finder colorIconOnBar = find.byIcon(Icons.format_paint_outlined);
+    expect(colorIconOnBar, findsOneWidget);
+    await tester.tap(colorIconOnBar);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    expect(colorIconOnBar, findsNothing);
+    expect(find.byIcon(Icons.format_paint), findsOneWidget);
+    expect(find.text("Light Theme"), findsOneWidget);
+    expect(find.text("Dark Theme"), findsOneWidget);
+  });
+
+  testWidgets(
+      'Color palettes screen shows correctly when color icon is clicked '
+      'on NavigationRail', (WidgetTester tester) async {
+    widgetSetup(tester, 450); // NavigationRail shows only when width is >= 450.
+    addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
+    await tester.pumpWidget(const Material3Demo());
+    expect(find.text("Light Theme"), findsNothing);
+    expect(find.text("Dark Theme"), findsNothing);
+    expect(find.byType(NavigationRail), findsOneWidget);
+    Finder colorIconOnRail = find.byIcon(Icons.format_paint_outlined);
+    expect(colorIconOnRail, findsOneWidget);
+    await tester.tap(colorIconOnRail);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    expect(colorIconOnRail, findsNothing);
+    expect(find.byIcon(Icons.format_paint), findsOneWidget);
+    expect(find.text("Light Theme"), findsOneWidget);
+    expect(find.text("Dark Theme"), findsOneWidget);
+  });
+
+  testWidgets('Color screen shows correct content',
+      (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(body: Row(children: const [ColorPalettesScreen()])),
+    ));
+    expect(find.text("Light Theme"), findsOneWidget);
+    expect(find.text("Dark Theme"), findsOneWidget);
+    expect(find.byType(ColorGroup, skipOffstage: false), findsNWidgets(14));
+  });
+}

material_3_demo/test/component_screen_test.dart

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+// ignore_for_file: avoid_types_on_closure_parameters
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:material_3_demo/component_screen.dart';
+import 'package:material_3_demo/main.dart';
+
+void main() {
+  testWidgets('Default main page shows all M3 components',
+      (WidgetTester tester) async {
+    await tester.pumpWidget(const Material3Demo());
+
+    // Elements on the app bar
+    expect(find.text('Material 3'), findsOneWidget);
+    expect(find.widgetWithIcon(IconButton, Icons.wb_sunny_outlined),
+        findsOneWidget);
+    expect(find.widgetWithIcon(IconButton, Icons.filter_3), findsOneWidget);
+    expect(find.widgetWithIcon(IconButton, Icons.more_vert), findsOneWidget);
+
+    // Elements on the component screen
+    // Buttons
+    expect(find.widgetWithText(ElevatedButton, "Elevated"), findsNWidgets(2));
+    expect(find.widgetWithText(ElevatedButton, "Filled"), findsNWidgets(2));
+    expect(
+        find.widgetWithText(ElevatedButton, "Filled Tonal"), findsNWidgets(2));
+    expect(find.widgetWithText(OutlinedButton, "Outlined"), findsNWidgets(2));
+    expect(find.widgetWithText(TextButton, "Text"), findsNWidgets(2));
+    expect(find.text("Icon"), findsNWidgets(5));
+
+    // FABs
+    expect(
+        find.widgetWithIcon(FloatingActionButton, Icons.add), findsNWidgets(4));
+    expect(find.widgetWithText(FloatingActionButton, "Create"), findsOneWidget);
+
+    // Cards
+    expect(find.widgetWithText(Card, "Elevated"), findsOneWidget);
+    expect(find.widgetWithText(Card, "Filled"), findsOneWidget);
+    expect(find.widgetWithText(Card, "Outlined"), findsOneWidget);
+
+    // Alert Dialog
+    Finder dialogExample = find.widgetWithText(TextButton, "Open Dialog");
+    await tester.scrollUntilVisible(
+      dialogExample,
+      500.0,
+    );
+    expect(dialogExample, findsOneWidget);
+  });
+
+  testWidgets(
+      'NavigationRail doesn\'t show when width value is small than 450 '
+      '(in Portrait mode or narrow screen)', (tester) async {
+    widgetSetup(tester, 449);
+    await tester.pumpWidget(const Material3Demo());
+
+    // When screen width is less than 450, NavigationBar will show. At the same
+    // time, the NavigationRail and the NavigationBar example will NOT show.
+    expect(find.byType(NavigationBars), findsOneWidget);
+    expect(find.widgetWithText(NavigationBar, "Components"), findsOneWidget);
+    expect(find.widgetWithText(NavigationBar, "Color"), findsOneWidget);
+    expect(find.widgetWithText(NavigationBar, "Typography"), findsOneWidget);
+    expect(find.widgetWithText(NavigationBar, "Elevation"), findsOneWidget);
+
+    expect(find.byType(NavigationRailSection), findsNothing);
+    expect(find.widgetWithText(NavigationBar, "Explore"), findsNothing);
+    expect(find.widgetWithText(NavigationBar, "Pets"), findsNothing);
+    expect(find.widgetWithText(NavigationBar, "Account"), findsNothing);
+  });
+
+  testWidgets(
+      'NavigationRail shows when width value is greater than or equal '
+      'to 450 (in Landscape mode or wider screen)', (tester) async {
+    widgetSetup(tester, 450);
+    await tester.pumpWidget(const Material3Demo());
+
+    // When screen width is greater than or equal to 450, NavigationRail and
+    // NavigationBar example will show. At the same time, the NavigationBar
+    // will NOT show.
+    expect(find.byType(NavigationRailSection), findsOneWidget);
+    expect(find.byType(Tooltip, skipOffstage: false), findsWidgets);
+    expect(find.widgetWithText(NavigationRailSection, "Components"),
+        findsOneWidget);
+    expect(find.widgetWithText(NavigationRailSection, "Color"), findsOneWidget);
+    expect(find.widgetWithText(NavigationRailSection, "Typography"),
+        findsOneWidget);
+    expect(find.widgetWithText(NavigationRailSection, "Elevation"),
+        findsOneWidget);
+
+    final navbarExample = find.byType(NavigationBars);
+    await tester.scrollUntilVisible(
+      navbarExample,
+      500.0,
+    );
+    expect(find.byType(NavigationBars), findsOneWidget);
+    expect(find.widgetWithText(NavigationBar, "Explore"), findsOneWidget);
+    expect(find.widgetWithText(NavigationBar, "Pets"), findsOneWidget);
+    expect(find.widgetWithText(NavigationBar, "Account"), findsOneWidget);
+
+    expect(find.widgetWithText(NavigationBar, "Components"), findsNothing);
+    expect(find.widgetWithText(NavigationBar, "Colors"), findsNothing);
+    expect(find.widgetWithText(NavigationBar, "Typography"), findsNothing);
+    expect(find.widgetWithText(NavigationBar, "Elevation"), findsNothing);
+  });
+
+  testWidgets(
+      'Material version switches between Material3 and Material2 when'
+      'the version icon is clicked', (tester) async {
+    await tester.pumpWidget(const Material3Demo());
+    Finder m3Icon = find.widgetWithIcon(IconButton, Icons.filter_3);
+    Finder m2Icon = find.widgetWithIcon(IconButton, Icons.filter_2);
+    BuildContext defaultElevatedButton =
+        tester.firstElement(find.byType(ElevatedButton));
+    BuildContext defaultFAB =
+        tester.firstElement(find.byType(FloatingActionButton));
+    BuildContext defaultCard = tester.firstElement(find.byType(Card));
+    Finder dialog = find.text("Open Dialog");
+    await tester.scrollUntilVisible(
+      dialog,
+      500.0,
+    );
+    await tester.tap(dialog);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    BuildContext defaultAlertDialog = tester.element(find.byType(AlertDialog));
+    expect(Theme.of(defaultAlertDialog).useMaterial3, true);
+    Finder dismiss = find.text("Dismiss");
+    await tester.scrollUntilVisible(
+      dismiss,
+      500.0,
+    );
+    await tester.tap(dismiss);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+
+    expect(m3Icon, findsOneWidget);
+    expect(m2Icon, findsNothing);
+    expect(find.text("Material 3"), findsOneWidget);
+    expect(Theme.of(defaultElevatedButton).useMaterial3, true);
+    expect(Theme.of(defaultFAB).useMaterial3, true);
+    expect(Theme.of(defaultCard).useMaterial3, true);
+
+    await tester.tap(m3Icon);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    BuildContext updatedElevatedButton =
+        tester.firstElement(find.byType(ElevatedButton));
+    BuildContext updatedFAB =
+        tester.firstElement(find.byType(FloatingActionButton));
+    BuildContext updatedCard = tester.firstElement(find.byType(Card));
+    Finder updatedDialog = find.text("Open Dialog");
+    await tester.scrollUntilVisible(
+      updatedDialog,
+      500.0,
+    );
+    await tester.tap(updatedDialog);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    BuildContext updatedAlertDialog =
+        tester.firstElement(find.byType(AlertDialog));
+    expect(Theme.of(updatedAlertDialog).useMaterial3, false);
+    Finder updatedDismiss = find.text("Dismiss");
+    await tester.scrollUntilVisible(
+      updatedDismiss,
+      500.0,
+    );
+    await tester.tap(updatedDismiss);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+
+    expect(m3Icon, findsNothing);
+    expect(m2Icon, findsOneWidget);
+    expect(find.text("Material 2"), findsOneWidget);
+    expect(Theme.of(updatedElevatedButton).useMaterial3, false);
+    expect(Theme.of(updatedFAB).useMaterial3, false);
+    expect(Theme.of(updatedCard).useMaterial3, false);
+  });
+
+  testWidgets(
+      'Other screens become Material2 mode after changing mode from '
+      'main screen', (tester) async {
+    await tester.pumpWidget(const Material3Demo());
+    await tester.tap(find.widgetWithIcon(IconButton, Icons.filter_3));
+    await tester.tap(find.byIcon(Icons.format_paint_outlined));
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    BuildContext lightThemeText = tester.element(find.text("Light Theme"));
+    expect(Theme.of(lightThemeText).useMaterial3, false);
+    await tester.tap(find.byIcon(Icons.text_snippet_outlined));
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    BuildContext displayLargeText = tester.element(find.text("Display Large"));
+    expect(Theme.of(displayLargeText).useMaterial3, false);
+    await tester.tap(find.byIcon(Icons.invert_colors_on_outlined));
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    BuildContext material = tester.firstElement(find.byType(Material));
+    expect(Theme.of(material).useMaterial3, false);
+  });
+
+  testWidgets(
+      'Brightness mode switches between dark and light when'
+      'the brightness icon is clicked', (tester) async {
+    await tester.pumpWidget(const Material3Demo());
+    Finder lightIcon = find.widgetWithIcon(IconButton, Icons.wb_sunny_outlined);
+    Finder darkIcon = find.widgetWithIcon(IconButton, Icons.wb_sunny);
+    BuildContext appBar = tester.element(find.byType(AppBar));
+    BuildContext body = tester.element(find.byType(Scaffold));
+    BuildContext navigationRail = tester.element(find.byType(NavigationRail));
+    expect(lightIcon, findsOneWidget);
+    expect(darkIcon, findsNothing);
+    expect(Theme.of(appBar).brightness, Brightness.light);
+    expect(Theme.of(body).brightness, Brightness.light);
+    expect(Theme.of(navigationRail).brightness, Brightness.light);
+    await tester.tap(lightIcon);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+
+    BuildContext appBar2 = tester.element(find.byType(AppBar));
+    BuildContext body2 = tester.element(find.byType(Scaffold));
+    BuildContext navigationRail2 = tester.element(find.byType(NavigationRail));
+    expect(lightIcon, findsNothing);
+    expect(darkIcon, findsOneWidget);
+    expect(Theme.of(appBar2).brightness, Brightness.dark);
+    expect(Theme.of(body2).brightness, Brightness.dark);
+    expect(Theme.of(navigationRail2).brightness, Brightness.dark);
+  });
+
+  testWidgets('Color theme changes when a color is selected from menu',
+      (tester) async {
+    await tester.pumpWidget(const Material3Demo());
+    Finder menuIcon = find.widgetWithIcon(IconButton, Icons.more_vert);
+    BuildContext appBar = tester.element(find.byType(AppBar));
+    BuildContext body = tester.element(find.byType(Scaffold));
+    BuildContext navigationRail = tester.element(find.byType(NavigationRail));
+
+    expect(Theme.of(appBar).primaryColor, m3BaseColor);
+    expect(Theme.of(body).primaryColor, m3BaseColor);
+    expect(Theme.of(navigationRail).primaryColor, m3BaseColor);
+    await tester.tap(menuIcon);
+    await tester.pumpAndSettle();
+    await tester.tap(find.text("Blue"));
+    await tester.pumpAndSettle();
+
+    BuildContext appBar2 = tester.element(find.byType(AppBar));
+    BuildContext body2 = tester.element(find.byType(Scaffold));
+    BuildContext navigationRail2 = tester.element(find.byType(NavigationRail));
+    ThemeData expectedTheme = ThemeData(colorSchemeSeed: Colors.blue);
+    expect(Theme.of(appBar2).primaryColor, expectedTheme.primaryColor);
+    expect(Theme.of(body2).primaryColor, expectedTheme.primaryColor);
+    expect(Theme.of(navigationRail2).primaryColor, expectedTheme.primaryColor);
+  });
+}
+
+void widgetSetup(WidgetTester tester, double width) {
+  const height = 846;
+  tester.binding.window.devicePixelRatioTestValue = (2);
+  final dpi = tester.binding.window.devicePixelRatio;
+  tester.binding.window.physicalSizeTestValue = Size(width * dpi, height * dpi);
+}

material_3_demo/test/elevation_screen_test.dart

@@ -0,0 +1,56 @@
+// ignore_for_file: avoid_types_on_closure_parameters
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:material_3_demo/elevation_screen.dart';
+import 'package:material_3_demo/main.dart';
+
+import 'component_screen_test.dart';
+
+void main() {
+  testWidgets(
+      'Surface Tones screen shows correctly when the corresponding icon is '
+      'selected on NavigationBar', (WidgetTester tester) async {
+    widgetSetup(tester, 449);
+    addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
+    await tester.pumpWidget(const Material3Demo());
+
+    expect(find.text("Surface Tint only"), findsNothing);
+    expect(find.byType(NavigationBar), findsOneWidget);
+    Finder tintIconOnBar = find.byIcon(Icons.invert_colors_on_outlined);
+    expect(tintIconOnBar, findsOneWidget);
+    await tester.tap(tintIconOnBar);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    expect(tintIconOnBar, findsNothing);
+    expect(find.byIcon(Icons.opacity), findsOneWidget);
+    expect(find.text("Surface Tint only"), findsOneWidget);
+  });
+
+  testWidgets(
+      'Surface Tones screen shows correctly when the corresponding icon is '
+      'selected on NavigationRail', (WidgetTester tester) async {
+    widgetSetup(tester, 450); // NavigationRail shows only when width is >= 450.
+    addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
+    await tester.pumpWidget(const Material3Demo());
+    expect(find.text("Surface Tint only"), findsNothing);
+    expect(find.byType(NavigationRail), findsOneWidget);
+    Finder tintIconOnRail = find.byIcon(Icons.invert_colors_on_outlined);
+    expect(tintIconOnRail, findsOneWidget);
+    await tester.tap(tintIconOnRail);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    expect(tintIconOnRail, findsNothing);
+    expect(find.byIcon(Icons.opacity), findsOneWidget);
+    expect(find.text("Surface Tint only"), findsOneWidget);
+  });
+
+  testWidgets('Surface Tones screen shows correct content',
+      (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(body: Row(children: const [ElevationScreen()])),
+    ));
+    expect(find.text("Surface Tint only"), findsOneWidget);
+    expect(find.text("Surface Tint and Shadow"), findsOneWidget);
+    expect(find.text("Shadow only"), findsOneWidget);
+    expect(find.byType(ElevationGrid), findsNWidgets(3));
+    expect(find.byType(ElevationCard), findsNWidgets(18));
+  });
+}

material_3_demo/test/typography_screen_test.dart

@@ -0,0 +1,72 @@
+// ignore_for_file: avoid_types_on_closure_parameters
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:material_3_demo/main.dart';
+import 'package:material_3_demo/typography_screen.dart';
+
+import 'component_screen_test.dart';
+
+void main() {
+  testWidgets(
+      'Typography screen shows correctly when the corresponding icon is '
+      'selected on NavigationBar', (WidgetTester tester) async {
+    widgetSetup(tester, 449);
+    addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
+    await tester.pumpWidget(const Material3Demo());
+
+    expect(find.text("Display Large"), findsNothing);
+    expect(find.byType(NavigationBar), findsOneWidget);
+    Finder textIconOnBar = find.byIcon(Icons.text_snippet_outlined);
+    expect(textIconOnBar, findsOneWidget);
+    await tester.tap(textIconOnBar);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    expect(textIconOnBar, findsNothing);
+    expect(find.byIcon(Icons.text_snippet), findsOneWidget);
+    expect(find.text("Display Large"), findsOneWidget);
+  });
+
+  testWidgets(
+      'Typography screen shows correctly when the corresponding icon is '
+      'selected on NavigationRail', (WidgetTester tester) async {
+    widgetSetup(tester, 450); // NavigationRail shows only when width is >= 450.
+    addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
+    await tester.pumpWidget(const Material3Demo());
+    expect(find.text("Display Large"), findsNothing);
+    expect(find.byType(NavigationRail), findsOneWidget);
+    Finder textIconOnRail = find.byIcon(Icons.text_snippet_outlined);
+    expect(textIconOnRail, findsOneWidget);
+    await tester.tap(textIconOnRail);
+    await tester.pumpAndSettle(const Duration(microseconds: 500));
+    expect(textIconOnRail, findsNothing);
+    expect(find.byIcon(Icons.text_snippet), findsOneWidget);
+    expect(find.text("Display Large"), findsOneWidget);
+  });
+
+  testWidgets('Typography screen shows correct content',
+      (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(body: Row(children: const [TypographyScreen()])),
+    ));
+    expect(find.text("Display Large"), findsOneWidget);
+    expect(find.text("Display Medium"), findsOneWidget);
+    expect(find.text("Display Small"), findsOneWidget);
+    expect(find.text("Headline Large"), findsOneWidget);
+    expect(find.text("Headline Medium"), findsOneWidget);
+    expect(find.text("Headline Small"), findsOneWidget);
+    expect(find.text("Title Large"), findsOneWidget);
+    expect(find.text("Title Medium"), findsOneWidget);
+    expect(find.text("Title Small"), findsOneWidget);
+    await tester.scrollUntilVisible(
+      find.text("Body Small"),
+      500.0,
+    );
+    expect(find.text("Label Large"), findsOneWidget);
+    expect(find.text("Label Medium"), findsOneWidget);
+    expect(find.text("Label Small"), findsOneWidget);
+    expect(find.text("Body Large"), findsOneWidget);
+    expect(find.text("Body Medium"), findsOneWidget);
+    expect(find.text("Body Small"), findsOneWidget);
+
+    expect(find.byType(TextStyleExample), findsNWidgets(15));
+  });
+}