SliverAppBar shape property (#33073)

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

@@ -687,6 +687,7 @@ class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
     @required this.floating,
     @required this.pinned,
     @required this.snapConfiguration,
+    @required this.shape,
   }) : assert(primary || topPadding == 0.0),
        _bottomHeight = bottom?.preferredSize?.height ?? 0.0;
 
@@ -711,6 +712,7 @@ class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
   final double topPadding;
   final bool floating;
   final bool pinned;
+  final ShapeBorder shape;
 
   final double _bottomHeight;
 
@@ -765,6 +767,7 @@ class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
         primary: primary,
         centerTitle: centerTitle,
         titleSpacing: titleSpacing,
+        shape: shape,
         toolbarOpacity: toolbarOpacity,
         bottomOpacity: pinned ? 1.0 : (visibleMainHeight / _bottomHeight).clamp(0.0, 1.0),
       ),
@@ -908,6 +911,7 @@ class SliverAppBar extends StatefulWidget {
     this.floating = false,
     this.pinned = false,
     this.snap = false,
+    this.shape,
   }) : assert(automaticallyImplyLeading != null),
        assert(forceElevated != null),
        assert(primary != null),
@@ -1125,6 +1129,12 @@ class SliverAppBar extends StatefulWidget {
   ///    behavior of the app bar in combination with [floating].
   final bool pinned;
 
+  /// The material's shape as well its shadow.
+  ///
+  /// A shadow is only displayed if the [elevation] is greater than
+  /// zero.
+  final ShapeBorder shape;
+
   /// If [snap] and [floating] are true then the floating app bar will "snap"
   /// into view.
   ///
@@ -1221,6 +1231,7 @@ class _SliverAppBarState extends State<SliverAppBar> with TickerProviderStateMix
           topPadding: topPadding,
           floating: widget.floating,
           pinned: widget.pinned,
+          shape: widget.shape,
           snapConfiguration: _snapConfiguration,
         ),
       ),

packages/flutter/test/material/app_bar_test.dart

@@ -1425,7 +1425,6 @@ void main() {
 
   testWidgets('Changing SliverAppBar snap from true to false', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/17598
-
     const double appBarHeight = 256.0;
     bool snap = true;
 
@@ -1486,32 +1485,99 @@ void main() {
     await tester.pump();
   });
 
+  testWidgets('AppBar shape default', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: AppBar(
+          leading: const Text('L'),
+          title: const Text('No Scaffold'),
+          actions: const <Widget>[Text('A1'), Text('A2')],
+        ),
+      ),
+    );
+
+    final Finder appBarFinder = find.byType(AppBar);
+    AppBar getAppBarWidget(Finder finder) => tester.widget<AppBar>(finder);
+    expect(getAppBarWidget(appBarFinder).shape, null);
+
+    final Finder materialFinder = find.byType(Material);
+    Material getMaterialWidget(Finder finder) => tester.widget<Material>(finder);
+    expect(getMaterialWidget(materialFinder).shape, null);
+  });
+
   testWidgets('AppBar with shape', (WidgetTester tester) async {
-    const RoundedRectangleBorder roundedRectangleBorder = RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(15.0)));
+    const RoundedRectangleBorder roundedRectangleBorder = RoundedRectangleBorder(
+      borderRadius: BorderRadius.all(Radius.circular(15.0))
+    );
     await tester.pumpWidget(
       MaterialApp(
         home: AppBar(
           leading: const Text('L'),
           title: const Text('No Scaffold'),
-          shape: roundedRectangleBorder,
           actions: const <Widget>[Text('A1'), Text('A2')],
+          shape: roundedRectangleBorder,
         ),
       ),
     );
 
     final Finder appBarFinder = find.byType(AppBar);
+    AppBar getAppBarWidget(Finder finder) => tester.widget<AppBar>(finder);
+    expect(getAppBarWidget(appBarFinder).shape, roundedRectangleBorder);
 
-    AppBar getAppBarWidget() {
-      return tester.widget<AppBar>(appBarFinder);
-    }
+    final Finder materialFinder = find.byType(Material);
+    Material getMaterialWidget(Finder finder) => tester.widget<Material>(finder);
+    expect(getMaterialWidget(materialFinder).shape, roundedRectangleBorder);
+  });
+
+  testWidgets('SliverAppBar shape default', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: CustomScrollView(
+          slivers: <Widget>[
+            SliverAppBar(
+              leading: Text('L'),
+              title: Text('No Scaffold'),
+              actions: <Widget>[Text('A1'), Text('A2')],
+            ),
+          ],
+        ),
+      ),
+    );
 
-    expect(getAppBarWidget().shape, roundedRectangleBorder);
+    final Finder sliverAppBarFinder = find.byType(SliverAppBar);
+    SliverAppBar getSliverAppBarWidget(Finder finder) => tester.widget<SliverAppBar>(finder);
+    expect(getSliverAppBarWidget(sliverAppBarFinder).shape, null);
 
     final Finder materialFinder = find.byType(Material);
-    Material getMaterialWidget() {
-      return tester.widget<Material>(materialFinder);
-    }
+    Material getMaterialWidget(Finder finder) => tester.widget<Material>(finder);
+    expect(getMaterialWidget(materialFinder).shape, null);
+  });
 
-    expect(getMaterialWidget().shape, roundedRectangleBorder);
+  testWidgets('SliverAppBar with shape', (WidgetTester tester) async {
+    const RoundedRectangleBorder roundedRectangleBorder = RoundedRectangleBorder(
+      borderRadius: BorderRadius.all(Radius.circular(15.0)),
+    );
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: CustomScrollView(
+          slivers: <Widget>[
+            SliverAppBar(
+              leading: Text('L'),
+              title: Text('No Scaffold'),
+              actions: <Widget>[Text('A1'), Text('A2')],
+              shape: roundedRectangleBorder,
+            ),
+          ],
+        ),
+      ),
+    );
+
+    final Finder sliverAppBarFinder = find.byType(SliverAppBar);
+    SliverAppBar getSliverAppBarWidget(Finder finder) => tester.widget<SliverAppBar>(finder);
+    expect(getSliverAppBarWidget(sliverAppBarFinder).shape, roundedRectangleBorder);
+
+    final Finder materialFinder = find.byType(Material);
+    Material getMaterialWidget(Finder finder) => tester.widget<Material>(finder);
+    expect(getMaterialWidget(materialFinder).shape, roundedRectangleBorder);
   });
 }