Update `DropdownMenu`, `SnackBarTheme` and `Stepper` tests for M2/M3 (#130464)

Updated unit tests for `DropdownMenu`, `SnackBarTheme` and `Stepper` to have M2 and M3 versions.

More info in #127064

packages/flutter/test/material/dropdown_menu_test.dart

@@ -5,6 +5,7 @@
 
 import 'dart:ui';
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
@@ -109,11 +110,10 @@ void main() {
     expect(updatedMenuMaterial, findsNothing);
   });
 
-  testWidgets('The width of the text field should always be the same as the menu view',
+  testWidgets('Material2 - The width of the text field should always be the same as the menu view',
     (WidgetTester tester) async {
 
     final ThemeData themeData = ThemeData(useMaterial3: false);
-    final bool useMaterial3 = themeData.useMaterial3;
     await tester.pumpWidget(
       MaterialApp(
         theme: themeData,
@@ -129,7 +129,7 @@ void main() {
 
     final Finder textField = find.byType(TextField);
     final Size anchorSize = tester.getSize(textField);
-    expect(anchorSize, useMaterial3 ? const Size(195.0, 60.0) : const Size(180.0, 56.0));
+    expect(anchorSize, const Size(180.0, 56.0));
 
     await tester.tap(find.byType(DropdownMenu<TestMenu>));
     await tester.pumpAndSettle();
@@ -139,7 +139,7 @@ void main() {
       matching: find.byType(Material),
     );
     final Size menuSize = tester.getSize(menuMaterial);
-    expect(menuSize, useMaterial3 ? const Size(195.0, 304.0) : const Size(180.0, 304.0));
+    expect(menuSize, const Size(180.0, 304.0));
 
     // The text field should have same width as the menu
     // when the width property is not null.
@@ -147,7 +147,64 @@ void main() {
 
     final Finder anchor = find.byType(TextField);
     final Size size = tester.getSize(anchor);
-    expect(size, useMaterial3 ? const Size(200.0, 60.0) : const Size(200.0, 56.0));
+    expect(size, const Size(200.0, 56.0));
+
+    await tester.tap(anchor);
+    await tester.pumpAndSettle();
+
+    final Finder updatedMenu = find.ancestor(
+      of: find.byType(SingleChildScrollView),
+      matching: find.byType(Material),
+    );
+    final Size updatedMenuSize = tester.getSize(updatedMenu);
+    expect(updatedMenuSize, const Size(200.0, 304.0));
+  });
+
+  testWidgets('Material3 - The width of the text field should always be the same as the menu view',
+    (WidgetTester tester) async {
+    final ThemeData themeData = ThemeData(useMaterial3: true);
+    await tester.pumpWidget(
+        MaterialApp(
+          theme: themeData,
+          home: Scaffold(
+            body: SafeArea(
+              child: DropdownMenu<TestMenu>(
+                dropdownMenuEntries: menuChildren,
+              ),
+            ),
+          ),
+        )
+    );
+
+    final Finder textField = find.byType(TextField);
+    final Size anchorSize = tester.getSize(textField);
+    if (kIsWeb && !isCanvasKit) {
+      expect(anchorSize, const Size(195.0, 61.0));
+    } else {
+      expect(anchorSize, const Size(195.0, 60.0));
+    }
+
+    await tester.tap(find.byType(DropdownMenu<TestMenu>));
+    await tester.pumpAndSettle();
+
+    final Finder menuMaterial = find.ancestor(
+      of: find.byType(SingleChildScrollView),
+      matching: find.byType(Material),
+    );
+    final Size menuSize = tester.getSize(menuMaterial);
+    expect(menuSize, const Size(195.0, 304.0));
+
+    // The text field should have same width as the menu
+    // when the width property is not null.
+    await tester.pumpWidget(buildTest(themeData, menuChildren, width: 200.0));
+
+    final Finder anchor = find.byType(TextField);
+    final Size size = tester.getSize(anchor);
+    if (kIsWeb && !isCanvasKit) {
+      expect(size, const Size(200.0, 61.0));
+    } else {
+      expect(size, const Size(200.0, 60.0));
+    }
 
     await tester.tap(anchor);
     await tester.pumpAndSettle();
@@ -280,10 +337,9 @@ void main() {
     expect(buttonSize.width, parentWidth - 35.0 - 20.0);
   });
 
-  testWidgets('The menuHeight property can be used to show a shorter scrollable menu list instead of the complete list',
+  testWidgets('Material2 - The menuHeight property can be used to show a shorter scrollable menu list instead of the complete list',
     (WidgetTester tester) async {
-    final ThemeData themeData = ThemeData();
-    final bool material3 = themeData.useMaterial3;
+    final ThemeData themeData = ThemeData(useMaterial3: false);
     await tester.pumpWidget(buildTest(themeData, menuChildren));
 
     await tester.tap(find.byType(DropdownMenu<TestMenu>));
@@ -303,7 +359,7 @@ void main() {
       matching: find.byType(Padding),
     ).first;
     final Size menuViewSize = tester.getSize(menuView);
-    expect(menuViewSize, material3 ? const Size(195.0, 304.0) : const Size(180.0, 304.0)); // 304 = 288 + vertical padding(2 * 8)
+    expect(menuViewSize, const Size(180.0, 304.0)); // 304 = 288 + vertical padding(2 * 8)
 
     // Constrains the menu height.
     await tester.pumpWidget(Container());
@@ -319,9 +375,50 @@ void main() {
     ).first;
 
     final Size updatedMenuSize = tester.getSize(updatedMenu);
-    expect(updatedMenuSize, material3 ? const Size(195.0, 100.0) : const Size(180.0, 100.0));
+    expect(updatedMenuSize, const Size(180.0, 100.0));
   });
 
+  testWidgets('Material3 - The menuHeight property can be used to show a shorter scrollable menu list instead of the complete list',
+    (WidgetTester tester) async {
+  final ThemeData themeData = ThemeData(useMaterial3: true);
+  await tester.pumpWidget(buildTest(themeData, menuChildren));
+
+  await tester.tap(find.byType(DropdownMenu<TestMenu>));
+  await tester.pumpAndSettle();
+
+  final Element firstItem = tester.element(find.widgetWithText(MenuItemButton, 'Item 0').last);
+  final RenderBox firstBox = firstItem.renderObject! as RenderBox;
+  final Offset topLeft = firstBox.localToGlobal(firstBox.size.topLeft(Offset.zero));
+  final Element lastItem = tester.element(find.widgetWithText(MenuItemButton, 'Item 5').last);
+  final RenderBox lastBox = lastItem.renderObject! as RenderBox;
+  final Offset bottomRight = lastBox.localToGlobal(lastBox.size.bottomRight(Offset.zero));
+  // height = height of MenuItemButton * 6 = 48 * 6
+  expect(bottomRight.dy - topLeft.dy, 288.0);
+
+  final Finder menuView = find.ancestor(
+    of: find.byType(SingleChildScrollView),
+    matching: find.byType(Padding),
+  ).first;
+  final Size menuViewSize = tester.getSize(menuView);
+  expect(menuViewSize, const Size(195.0, 304.0)); // 304 = 288 + vertical padding(2 * 8)
+
+  // Constrains the menu height.
+  await tester.pumpWidget(Container());
+  await tester.pumpWidget(buildTest(themeData, menuChildren, menuHeight: 100));
+  await tester.pumpAndSettle();
+
+  await tester.tap(find.byType(DropdownMenu<TestMenu>));
+  await tester.pumpAndSettle();
+
+  final Finder updatedMenu = find.ancestor(
+    of: find.byType(SingleChildScrollView),
+    matching: find.byType(Padding),
+  ).first;
+
+  final Size updatedMenuSize = tester.getSize(updatedMenu);
+  expect(updatedMenuSize, const Size(195.0, 100.0));
+});
+
   testWidgets('The text in the menu button should be aligned with the text of '
     'the text field - LTR', (WidgetTester tester) async {
     final ThemeData themeData = ThemeData();

packages/flutter/test/material/snack_bar_theme_test.dart

@@ -96,10 +96,43 @@ void main() {
     ]);
   });
 
-  testWidgets('Passing no SnackBarThemeData returns defaults', (WidgetTester tester) async {
+  testWidgets('Material2 - Passing no SnackBarThemeData returns defaults', (WidgetTester tester) async {
     const String text = 'I am a snack bar.';
-    final ThemeData theme = ThemeData();
-    final bool material3 = theme.useMaterial3;
+    await tester.pumpWidget(MaterialApp(
+      theme: ThemeData(useMaterial3: false),
+      home: Scaffold(
+        body: Builder(
+          builder: (BuildContext context) {
+            return GestureDetector(
+              onTap: () {
+                ScaffoldMessenger.of(context).showSnackBar(SnackBar(
+                  content: const Text(text),
+                  duration: const Duration(seconds: 2),
+                  action: SnackBarAction(label: 'ACTION', onPressed: () {}),
+                ));
+              },
+              child: const Text('X'),
+            );
+          },
+        ),
+      ),
+    ));
+
+    await tester.tap(find.text('X'));
+    await tester.pumpAndSettle();
+
+    final Material material = _getSnackBarMaterial(tester);
+    final RenderParagraph content = _getSnackBarTextRenderObject(tester, text);
+
+    expect(content.text.style, Typography.material2018().white.titleMedium);
+    expect(material.color, const Color(0xFF333333));
+    expect(material.elevation, 6.0);
+    expect(material.shape, null);
+  });
+
+  testWidgets('Material3 - Passing no SnackBarThemeData returns defaults', (WidgetTester tester) async {
+    const String text = 'I am a snack bar.';
+    final ThemeData theme = ThemeData(useMaterial3: true);
     await tester.pumpWidget(MaterialApp(
       theme: theme,
       home: Scaffold(
@@ -126,10 +159,8 @@ void main() {
     final Material material = _getSnackBarMaterial(tester);
     final RenderParagraph content = _getSnackBarTextRenderObject(tester, text);
 
-    expect(content.text.style, material3
-      ? Typography.material2021().englishLike.bodyMedium?.merge(Typography.material2021().black.bodyMedium).copyWith(color: theme.colorScheme.onInverseSurface, decorationColor: theme.colorScheme.onSurface)
-      : Typography.material2018().white.titleMedium);
-    expect(material.color, material3 ? theme.colorScheme.inverseSurface : const Color(0xFF333333));
+    expect(content.text.style, Typography.material2021().englishLike.bodyMedium?.merge(Typography.material2021().black.bodyMedium).copyWith(color: theme.colorScheme.onInverseSurface, decorationColor: theme.colorScheme.onSurface));
+    expect(material.color, theme.colorScheme.inverseSurface);
     expect(material.elevation, 6.0);
     expect(material.shape, null);
   });