Update BottomSheet test for M3 + fix an issue in elevation resolution (#136071)

This PR updates unit tests from bottom sheet tests for M3 migration.

More info in https://github.com/flutter/flutter/issues/127064

It also contains in bottom_sheet.dart where a default value took precedence over a theme attribute.

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

@@ -1071,7 +1071,7 @@ class ModalBottomSheetRoute<T> extends PopupRoute<T> {
           return _ModalBottomSheet<T>(
             route: this,
             backgroundColor: backgroundColor ?? sheetTheme.modalBackgroundColor ?? sheetTheme.backgroundColor ?? defaults.backgroundColor,
-            elevation: elevation ?? sheetTheme.modalElevation ?? defaults.modalElevation ?? sheetTheme.elevation,
+            elevation: elevation ?? sheetTheme.modalElevation ?? sheetTheme.elevation ?? defaults.modalElevation,
             shape: shape,
             clipBehavior: clipBehavior,
             constraints: constraints,

packages/flutter/test/material/bottom_sheet_test.dart

@@ -911,7 +911,7 @@ void main() {
     expect(modalBarrier.color, barrierColor);
   });
 
-  testWidgetsWithLeakTracking('BottomSheet uses fallback values in material3',
+  testWidgetsWithLeakTracking('Material3 - BottomSheet uses fallback values',
       (WidgetTester tester) async {
     const Color surfaceColor = Colors.pink;
     const Color surfaceTintColor = Colors.blue;
@@ -951,7 +951,7 @@ void main() {
     expect(tester.getSize(finder).width, 640);
   });
 
-  testWidgetsWithLeakTracking('BottomSheet has transparent shadow in material3', (WidgetTester tester) async {
+  testWidgetsWithLeakTracking('Material3 - BottomSheet has transparent shadow', (WidgetTester tester) async {
     await tester.pumpWidget(MaterialApp(
       theme: ThemeData(
         useMaterial3: true,
@@ -975,7 +975,7 @@ void main() {
     expect(material.shadowColor, Colors.transparent);
   });
 
-  testWidgetsWithLeakTracking('modal BottomSheet with scrollController has semantics', (WidgetTester tester) async {
+  testWidgetsWithLeakTracking('Material2 - Modal BottomSheet with ScrollController has semantics', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);
     final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
 
@@ -1048,12 +1048,89 @@ void main() {
     semantics.dispose();
   });
 
-  testWidgetsWithLeakTracking('modal BottomSheet with drag handle has semantics', (WidgetTester tester) async {
+  testWidgetsWithLeakTracking('Material3 - Modal BottomSheet with ScrollController has semantics', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);
     final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
 
     await tester.pumpWidget(MaterialApp(
-      theme: ThemeData.light(useMaterial3: true),
+      theme: ThemeData(useMaterial3: true),
+      home: Scaffold(
+        key: scaffoldKey,
+        body: const Center(child: Text('body')),
+      ),
+    ));
+
+    showModalBottomSheet<void>(
+      context: scaffoldKey.currentContext!,
+      builder: (BuildContext context) {
+        return DraggableScrollableSheet(
+          expand: false,
+          builder: (_, ScrollController controller) {
+            return SingleChildScrollView(
+              controller: controller,
+              child: const Text('BottomSheet'),
+            );
+          },
+        );
+      },
+    );
+
+    await tester.pump(); // bottom sheet show animation starts
+    await tester.pump(const Duration(seconds: 1)); // animation done
+
+    expect(semantics, hasSemantics(TestSemantics.root(
+      children: <TestSemantics>[
+        TestSemantics.rootChild(
+          children: <TestSemantics>[
+            TestSemantics(
+              children: <TestSemantics>[
+                TestSemantics(
+                  label: 'Dialog',
+                  textDirection: TextDirection.ltr,
+                  flags: <SemanticsFlag>[
+                    SemanticsFlag.scopesRoute,
+                    SemanticsFlag.namesRoute,
+                  ],
+                  children: <TestSemantics>[
+                    TestSemantics(
+                      children: <TestSemantics>[
+                        TestSemantics(
+                          flags: <SemanticsFlag>[SemanticsFlag.hasImplicitScrolling],
+                          children: <TestSemantics>[
+                            TestSemantics(
+                              label: 'BottomSheet',
+                              textDirection: TextDirection.ltr,
+                            ),
+                          ],
+                        ),
+                      ],
+                    ),
+                  ],
+                ),
+              ],
+            ),
+            TestSemantics(
+              children: <TestSemantics>[
+                TestSemantics(
+                  actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.dismiss],
+                  label: 'Scrim',
+                  textDirection: TextDirection.ltr,
+                ),
+              ],
+            ),
+          ],
+        ),
+      ],
+    ), ignoreTransform: true, ignoreRect: true, ignoreId: true));
+    semantics.dispose();
+  });
+
+  testWidgetsWithLeakTracking('Material3 - Modal BottomSheet with drag handle has semantics', (WidgetTester tester) async {
+    final SemanticsTester semantics = SemanticsTester(tester);
+    final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
+
+    await tester.pumpWidget(MaterialApp(
+      theme: ThemeData(useMaterial3: true),
       home: Scaffold(
         key: scaffoldKey,
         body: const Center(child: Text('body')),
@@ -1123,7 +1200,7 @@ void main() {
     const Color hoveringColor=Colors.green;
 
     await tester.pumpWidget(MaterialApp(
-      theme: ThemeData.light(useMaterial3: true).copyWith(
+      theme: ThemeData.light().copyWith(
         bottomSheetTheme:  BottomSheetThemeData(
           dragHandleColor: MaterialStateColor.resolveWith((Set<MaterialState> states) {
             if (states.contains(MaterialState.hovered)) {
@@ -1139,7 +1216,6 @@ void main() {
       ),
     ));
 
-
     showModalBottomSheet<void>(
       context: scaffoldKey.currentContext!,
       showDragHandle: true,
@@ -1182,7 +1258,6 @@ void main() {
 
   testWidgetsWithLeakTracking('showModalBottomSheet does not use root Navigator by default', (WidgetTester tester) async {
     await tester.pumpWidget(MaterialApp(
-      theme: ThemeData(useMaterial3: false),
       home: Scaffold(
         body: Navigator(onGenerateRoute: (RouteSettings settings) => MaterialPageRoute<void>(builder: (_) {
           return const _TestPage();
@@ -1207,7 +1282,8 @@ void main() {
 
     // Bottom sheet is displayed in correct position within the inner navigator
     // and above the BottomNavigationBar.
-    expect(tester.getBottomLeft(find.byType(BottomSheet)).dy, 544.0);
+    final double tabBarHeight = tester.getSize(find.byType(BottomNavigationBar)).height;
+    expect(tester.getBottomLeft(find.byType(BottomSheet)).dy, 600 - tabBarHeight);
   });
 
   testWidgetsWithLeakTracking('showModalBottomSheet uses root Navigator when specified', (WidgetTester tester) async {
@@ -1790,10 +1866,10 @@ void main() {
   });
 
   group('constraints', () {
-    testWidgetsWithLeakTracking('default constraints are max width 640 in material 3', (WidgetTester tester) async {
+    testWidgetsWithLeakTracking('Material3 - Default constraints are max width 640', (WidgetTester tester) async {
       await tester.pumpWidget(
         MaterialApp(
-          theme: ThemeData.light(useMaterial3: true),
+          theme: ThemeData(useMaterial3: true),
           home: const MediaQuery(
             data: MediaQueryData(size: Size(1000, 1000)),
             child: Scaffold(
@@ -1806,8 +1882,9 @@ void main() {
       expect(tester.getSize(find.byType(Placeholder)).width, 640);
     });
 
-    testWidgetsWithLeakTracking('No constraints by default for bottomSheet property', (WidgetTester tester) async {
+    testWidgetsWithLeakTracking('Material2 - No constraints by default for bottomSheet property', (WidgetTester tester) async {
       await tester.pumpWidget(MaterialApp(
+        // This test is specific to Material2 because Material3 sets constraints by default for BottomSheet.
         theme: ThemeData(useMaterial3: false),
         home: const Scaffold(
           body: Center(child: Text('body')),
@@ -1823,6 +1900,7 @@ void main() {
 
     testWidgetsWithLeakTracking('No constraints by default for showBottomSheet', (WidgetTester tester) async {
       await tester.pumpWidget(MaterialApp(
+        // This test is specific to Material2 because Material3 sets constraints by default for BottomSheet.
         theme: ThemeData(useMaterial3: false),
         home: Scaffold(
           body: Builder(builder: (BuildContext context) {
@@ -1851,6 +1929,7 @@ void main() {
 
     testWidgetsWithLeakTracking('No constraints by default for showModalBottomSheet', (WidgetTester tester) async {
       await tester.pumpWidget(MaterialApp(
+        // This test is specific to Material2 because Material3 sets constraints by default for BottomSheet.
         theme: ThemeData(useMaterial3: false),
         home: Scaffold(
           body: Builder(builder: (BuildContext context) {
@@ -1878,7 +1957,35 @@ void main() {
       );
     });
 
-    testWidgetsWithLeakTracking('Theme constraints used for bottomSheet property', (WidgetTester tester) async {
+    testWidgetsWithLeakTracking('Material3 - Theme constraints used for bottomSheet property', (WidgetTester tester) async {
+      const double sheetMaxWidth = 80.0;
+      await tester.pumpWidget(MaterialApp(
+        theme: ThemeData(
+          useMaterial3: true,
+          bottomSheetTheme: const BottomSheetThemeData(
+            constraints: BoxConstraints(maxWidth: sheetMaxWidth),
+          ),
+        ),
+        home: Scaffold(
+          body: const Center(child: Text('body')),
+          bottomSheet: const Text('BottomSheet'),
+          floatingActionButton: FloatingActionButton(onPressed: () {}, child: const Icon(Icons.add)),
+        ),
+      ));
+      expect(find.text('BottomSheet'), findsOneWidget);
+
+      // Should be centered and only 80dp wide.
+      final Rect bottomSheetRect = tester.getRect(find.text('BottomSheet'));
+      expect(bottomSheetRect.left, 800 / 2 - sheetMaxWidth / 2);
+      expect(bottomSheetRect.width, sheetMaxWidth);
+
+      // Ensure the FAB is overlapping the top of the sheet.
+      expect(find.byIcon(Icons.add), findsOneWidget);
+      final Rect iconRect = tester.getRect(find.byIcon(Icons.add));
+      expect(iconRect.top, bottomSheetRect.top - iconRect.height / 2);
+    });
+
+    testWidgetsWithLeakTracking('Material2 - Theme constraints used for bottomSheet property', (WidgetTester tester) async {
       await tester.pumpWidget(MaterialApp(
         theme: ThemeData(
           useMaterial3: false,
@@ -1907,11 +2014,11 @@ void main() {
     });
 
     testWidgetsWithLeakTracking('Theme constraints used for showBottomSheet', (WidgetTester tester) async {
+      const double sheetMaxWidth = 80.0;
       await tester.pumpWidget(MaterialApp(
         theme: ThemeData(
-          useMaterial3: false,
           bottomSheetTheme: const BottomSheetThemeData(
-            constraints: BoxConstraints(maxWidth: 80),
+            constraints: BoxConstraints(maxWidth: sheetMaxWidth),
           ),
         ),
         home: Scaffold(
@@ -1933,19 +2040,19 @@ void main() {
       await tester.tap(find.text('Press me'));
       await tester.pumpAndSettle();
       expect(find.text('BottomSheet'), findsOneWidget);
-      // Should be centered and only 80dp wide
-      expect(
-        tester.getRect(find.text('BottomSheet')),
-        const Rect.fromLTRB(360, 558, 440, 600),
-      );
+
+      // Should be centered and only 80dp wide.
+      final Rect bottomSheetRect = tester.getRect(find.text('BottomSheet'));
+      expect(bottomSheetRect.left, 800 / 2 - sheetMaxWidth / 2);
+      expect(bottomSheetRect.width, sheetMaxWidth);
     });
 
     testWidgetsWithLeakTracking('Theme constraints used for showModalBottomSheet', (WidgetTester tester) async {
+      const double sheetMaxWidth = 80.0;
       await tester.pumpWidget(MaterialApp(
         theme: ThemeData(
-          useMaterial3: false,
           bottomSheetTheme: const BottomSheetThemeData(
-            constraints: BoxConstraints(maxWidth: 80),
+            constraints: BoxConstraints(maxWidth: sheetMaxWidth),
           ),
         ),
         home: Scaffold(
@@ -1968,17 +2075,17 @@ void main() {
       await tester.tap(find.text('Press me'));
       await tester.pumpAndSettle();
       expect(find.text('BottomSheet'), findsOneWidget);
-      // Should be centered and only 80dp wide
-      expect(
-        tester.getRect(find.text('BottomSheet')),
-        const Rect.fromLTRB(360, 558, 440, 600),
-      );
+
+      // Should be centered and only 80dp wide.
+      final Rect bottomSheetRect = tester.getRect(find.text('BottomSheet'));
+      expect(bottomSheetRect.left, 800 / 2 - sheetMaxWidth / 2);
+      expect(bottomSheetRect.width, sheetMaxWidth);
     });
 
     testWidgetsWithLeakTracking('constraints param overrides theme for showBottomSheet', (WidgetTester tester) async {
+      const double sheetMaxWidth = 100.0;
       await tester.pumpWidget(MaterialApp(
         theme: ThemeData(
-          useMaterial3: false,
           bottomSheetTheme: const BottomSheetThemeData(
             constraints: BoxConstraints(maxWidth: 80),
           ),
@@ -1991,7 +2098,7 @@ void main() {
                 onPressed: () {
                   Scaffold.of(context).showBottomSheet<void>(
                     (BuildContext context) => const Text('BottomSheet'),
-                    constraints: const BoxConstraints(maxWidth: 100),
+                    constraints: const BoxConstraints(maxWidth: sheetMaxWidth),
                   );
                 },
               ),
@@ -2003,17 +2110,17 @@ void main() {
       await tester.tap(find.text('Press me'));
       await tester.pumpAndSettle();
       expect(find.text('BottomSheet'), findsOneWidget);
-      // Should be centered and only 100dp wide instead of 80dp wide
-      expect(
-        tester.getRect(find.text('BottomSheet')),
-        const Rect.fromLTRB(350, 572, 450, 600),
-      );
+
+      // Should be centered and only 80dp wide.
+      final Rect bottomSheetRect = tester.getRect(find.text('BottomSheet'));
+      expect(bottomSheetRect.left, 800 / 2 - sheetMaxWidth / 2);
+      expect(bottomSheetRect.width, sheetMaxWidth);
     });
 
     testWidgetsWithLeakTracking('constraints param overrides theme for showModalBottomSheet', (WidgetTester tester) async {
+      const double sheetMaxWidth = 100.0;
       await tester.pumpWidget(MaterialApp(
         theme: ThemeData(
-          useMaterial3: false,
           bottomSheetTheme: const BottomSheetThemeData(
             constraints: BoxConstraints(maxWidth: 80),
           ),
@@ -2027,7 +2134,7 @@ void main() {
                   showModalBottomSheet<void>(
                     context: context,
                     builder: (BuildContext context) => const Text('BottomSheet'),
-                    constraints: const BoxConstraints(maxWidth: 100),
+                    constraints: const BoxConstraints(maxWidth: sheetMaxWidth),
                   );
                 },
               ),
@@ -2039,11 +2146,11 @@ void main() {
       await tester.tap(find.text('Press me'));
       await tester.pumpAndSettle();
       expect(find.text('BottomSheet'), findsOneWidget);
-      // Should be centered and only 100dp instead of 80dp wide
-      expect(
-        tester.getRect(find.text('BottomSheet')),
-        const Rect.fromLTRB(350, 572, 450, 600),
-      );
+
+      // Should be centered and only 80dp wide.
+      final Rect bottomSheetRect = tester.getRect(find.text('BottomSheet'));
+      expect(bottomSheetRect.left, 800 / 2 - sheetMaxWidth / 2);
+      expect(bottomSheetRect.width, sheetMaxWidth);
     });
 
     group('scrollControlDisabledMaxHeightRatio', () {

packages/flutter/test/material/bottom_sheet_theme_test.dart

@@ -79,7 +79,34 @@ void main() {
     ]);
   });
 
-  testWidgetsWithLeakTracking('Passing no BottomSheetThemeData returns defaults', (WidgetTester tester) async {
+  testWidgetsWithLeakTracking('Material3 - Passing no BottomSheetThemeData returns defaults', (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      theme: ThemeData(useMaterial3: true),
+      home: Scaffold(
+        body: BottomSheet(
+          onClosing: () {},
+          builder: (BuildContext context) {
+            return Container();
+          },
+        ),
+      ),
+    ));
+
+    final Material material = tester.widget<Material>(
+      find.descendant(
+        of: find.byType(BottomSheet),
+        matching: find.byType(Material),
+      ),
+    );
+
+    final ThemeData theme = Theme.of(tester.element(find.byType(Scaffold)));
+    expect(material.color, theme.colorScheme.surface);
+    expect(material.elevation, 1.0);
+    expect(material.shape, const RoundedRectangleBorder(borderRadius: BorderRadius.vertical(top: Radius.circular(28.0))));
+    expect(material.clipBehavior, Clip.none);
+  });
+
+  testWidgetsWithLeakTracking('Material2 - Passing no BottomSheetThemeData returns defaults', (WidgetTester tester) async {
     await tester.pumpWidget(MaterialApp(
       theme: ThemeData(useMaterial3: false),
       home: Scaffold(
@@ -227,7 +254,7 @@ void main() {
     expect(material.color, persistentBackgroundColor);
   });
 
-  testWidgetsWithLeakTracking("Modal bottom sheet-specific parameters don't apply to persistent bottom sheets", (WidgetTester tester) async {
+  testWidgetsWithLeakTracking("Material3 - Modal bottom sheet-specific parameters don't apply to persistent bottom sheets", (WidgetTester tester) async {
     const double modalElevation = 5.0;
     const Color modalBackgroundColor = Colors.yellow;
     const BottomSheetThemeData bottomSheetTheme = BottomSheetThemeData(
@@ -239,6 +266,29 @@ void main() {
     await tester.tap(find.text('Show Persistent'));
     await tester.pumpAndSettle();
 
+    final Material material = tester.widget<Material>(
+      find.descendant(
+        of: find.byType(BottomSheet),
+        matching: find.byType(Material),
+      ),
+    );
+    expect(material.elevation, 1.0);
+    final ThemeData theme = Theme.of(tester.element(find.byType(Scaffold)));
+    expect(material.color, theme.colorScheme.surface);
+  });
+
+  testWidgetsWithLeakTracking("Material2 - Modal bottom sheet-specific parameters don't apply to persistent bottom sheets", (WidgetTester tester) async {
+    const double modalElevation = 5.0;
+    const Color modalBackgroundColor = Colors.yellow;
+    const BottomSheetThemeData bottomSheetTheme = BottomSheetThemeData(
+      modalElevation: modalElevation,
+      modalBackgroundColor: modalBackgroundColor,
+    );
+
+    await tester.pumpWidget(bottomSheetWithElevations(bottomSheetTheme, useMaterial3: false));
+    await tester.tap(find.text('Show Persistent'));
+    await tester.pumpAndSettle();
+
     final Material material = tester.widget<Material>(
       find.descendant(
         of: find.byType(BottomSheet),
@@ -258,14 +308,14 @@ void main() {
     const Color darkShadowColor = Colors.purple;
 
     await tester.pumpWidget(MaterialApp(
-      theme: ThemeData.light(useMaterial3: false).copyWith(
+      theme: ThemeData.light().copyWith(
         bottomSheetTheme: const BottomSheetThemeData(
           elevation: lightElevation,
           backgroundColor: lightBackgroundColor,
           shadowColor: lightShadowColor,
         ),
       ),
-      darkTheme: ThemeData.dark(useMaterial3: false).copyWith(
+      darkTheme: ThemeData.dark().copyWith(
         bottomSheetTheme: const BottomSheetThemeData(
           elevation: darkElevation,
           backgroundColor: darkBackgroundColor,
@@ -323,9 +373,9 @@ void main() {
   });
 }
 
-Widget bottomSheetWithElevations(BottomSheetThemeData bottomSheetTheme) {
+Widget bottomSheetWithElevations(BottomSheetThemeData bottomSheetTheme, {bool useMaterial3 = true}) {
   return MaterialApp(
-    theme: ThemeData(bottomSheetTheme: bottomSheetTheme, useMaterial3: false),
+    theme: ThemeData(bottomSheetTheme: bottomSheetTheme, useMaterial3: useMaterial3),
     home: Scaffold(
       body: Builder(
         builder: (BuildContext context) {