Add default arguments to AnimatedPhysicalModel (#147424)

Currently, `PhysicalModel` has [default arguments](https://github.com/flutter/flutter/blob/2e806700b9287c4b4f9fc49fbdfbd81089fc65dd/packages/flutter/lib/src/widgets/basic.dart#L1093) for `shape` and `elevation`, but `AnimatedPhysicalModel` [does not](https://github.com/flutter/flutter/blob/2e806700b9287c4b4f9fc49fbdfbd81089fc65dd/packages/flutter/lib/src/widgets/implicit_animations.dart#L1998).

This pull request makes both classes consistent.

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

@@ -503,7 +503,6 @@ class _MaterialState extends State<Material> with TickerProviderStateMixin {
       return AnimatedPhysicalModel(
         curve: Curves.fastOutSlowIn,
         duration: widget.animationDuration,
-        shape: BoxShape.rectangle,
         clipBehavior: widget.clipBehavior,
         elevation: modelElevation,
         color: color,

packages/flutter/lib/src/widgets/implicit_animations.dart

@@ -1995,10 +1995,10 @@ class AnimatedPhysicalModel extends ImplicitlyAnimatedWidget {
   const AnimatedPhysicalModel({
     super.key,
     required this.child,
-    required this.shape,
+    this.shape = BoxShape.rectangle,
     this.clipBehavior = Clip.none,
-    this.borderRadius = BorderRadius.zero,
-    required this.elevation,
+    this.borderRadius,
+    this.elevation = 0.0,
     required this.color,
     this.animateColor = true,
     required this.shadowColor,
@@ -2024,7 +2024,9 @@ class AnimatedPhysicalModel extends ImplicitlyAnimatedWidget {
   final Clip clipBehavior;
 
   /// The target border radius of the rounded corners for a rectangle shape.
-  final BorderRadius borderRadius;
+  ///
+  /// If null, treated as [BorderRadius.zero].
+  final BorderRadius? borderRadius;
 
   /// The target z-coordinate relative to the parent at which to place this
   /// physical object.
@@ -2068,10 +2070,26 @@ class _AnimatedPhysicalModelState extends AnimatedWidgetBaseState<AnimatedPhysic
 
   @override
   void forEachTween(TweenVisitor<dynamic> visitor) {
-    _borderRadius = visitor(_borderRadius, widget.borderRadius, (dynamic value) => BorderRadiusTween(begin: value as BorderRadius)) as BorderRadiusTween?;
-    _elevation = visitor(_elevation, widget.elevation, (dynamic value) => Tween<double>(begin: value as double)) as Tween<double>?;
-    _color = visitor(_color, widget.color, (dynamic value) => ColorTween(begin: value as Color)) as ColorTween?;
-    _shadowColor = visitor(_shadowColor, widget.shadowColor, (dynamic value) => ColorTween(begin: value as Color)) as ColorTween?;
+    _borderRadius = visitor(
+      _borderRadius,
+      widget.borderRadius ?? BorderRadius.zero,
+      (dynamic value) => BorderRadiusTween(begin: value as BorderRadius),
+    ) as BorderRadiusTween?;
+    _elevation = visitor(
+      _elevation,
+      widget.elevation,
+      (dynamic value) => Tween<double>(begin: value as double),
+    ) as Tween<double>?;
+    _color = visitor(
+      _color,
+      widget.color,
+      (dynamic value) => ColorTween(begin: value as Color),
+    ) as ColorTween?;
+    _shadowColor = visitor(
+      _shadowColor,
+      widget.shadowColor,
+      (dynamic value) => ColorTween(begin: value as Color),
+    ) as ColorTween?;
   }
 
   @override

packages/flutter/test/widgets/implicit_animations_test.dart

@@ -649,6 +649,29 @@ void main() {
 
     expect(secondCurvedAnimation.isDisposed, isTrue);
   });
+
+  group('Verify that default args match non-animated variants', () {
+    const Widget child = SizedBox.shrink();
+    const Color color = Color(0x00000000);
+
+    testWidgets('PhysicalModel default args', (WidgetTester tester) async {
+      const AnimatedPhysicalModel animatedPhysicalModel = AnimatedPhysicalModel(
+        duration: Duration.zero,
+        color: color,
+        shadowColor: color,
+        child: child,
+      );
+      const PhysicalModel physicalModel = PhysicalModel(
+        color: color,
+        shadowColor: color,
+        child: child,
+      );
+      expect(identical(animatedPhysicalModel.shape, physicalModel.shape), isTrue);
+      expect(identical(animatedPhysicalModel.clipBehavior, physicalModel.clipBehavior), isTrue);
+      expect(identical(animatedPhysicalModel.borderRadius, physicalModel.borderRadius), isTrue);
+    });
+    // TODO(nate-thegrate): add every class!
+  });
 }
 
 Future<void> tapTest2and3(WidgetTester tester, Finder widgetFinder,
@@ -904,9 +927,7 @@ class _TestAnimatedPhysicalModelWidgetState extends _TestAnimatedWidgetState {
       duration: duration,
       onEnd: widget.callback,
       color: toggle ? Colors.red : Colors.green,
-      elevation: 0,
       shadowColor: Colors.blue,
-      shape: BoxShape.rectangle,
       child: child,
     );
   }