Replace `MaterialButton` in the `AnimatedBuilder` sample (#1729)

animations/lib/src/basics/animated_builder.dart

@@ -23,7 +23,6 @@ class _AnimatedBuilderDemoState extends State<AnimatedBuilderDemo>
   @override
   void initState() {
     super.initState();
-
     controller = AnimationController(vsync: this, duration: duration);
     animation =
         ColorTween(begin: beginColor, end: endColor).animate(controller);
@@ -49,10 +48,10 @@ class _AnimatedBuilderDemoState extends State<AnimatedBuilderDemo>
         child: AnimatedBuilder(
           animation: animation,
           builder: (context, child) {
-            return MaterialButton(
-              color: animation.value,
-              height: 50,
-              minWidth: 100,
+            return ElevatedButton(
+              style: ElevatedButton.styleFrom(
+                backgroundColor: animation.value,
+              ),
               child: child,
               onPressed: () {
                 if (controller.status == AnimationStatus.completed) {

animations/test/basics/animated_builder_test.dart

@@ -0,0 +1,64 @@
+// Copyright 2023 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:animations/src/basics/basics.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+Widget createAnimatedBuilderDemoScreen() => const MaterialApp(
+      home: AnimatedBuilderDemo(),
+    );
+
+void main() {
+  group('AnimatedBuilder Tests', () {
+    testWidgets('AnimatedBuilder changes button color', (tester) async {
+      await tester.pumpWidget(createAnimatedBuilderDemoScreen());
+
+      // Get the initial color of the button.
+      ElevatedButton button = tester.widget(find.byType(ElevatedButton));
+      MaterialStateProperty<Color?>? initialColor =
+          button.style!.backgroundColor;
+
+      // Tap the button.
+      await tester.tap(find.byType(ElevatedButton));
+      await tester.pumpAndSettle();
+
+      // Get the updated color of the button.
+      button = tester.widget(find.byType(ElevatedButton));
+      MaterialStateProperty<Color?>? updatedColor =
+          button.style!.backgroundColor;
+
+      // Check if the color has changed.
+      expect(initialColor, isNot(updatedColor));
+    });
+
+    testWidgets('AnimatedBuilder animates button color', (tester) async {
+      await tester.pumpWidget(createAnimatedBuilderDemoScreen());
+
+      // Get the initial color of the button.
+      ElevatedButton button = tester.widget(find.byType(ElevatedButton));
+      MaterialStateProperty<Color?>? initialColor =
+          button.style!.backgroundColor;
+
+      // Tap the button to trigger the animation but don't wait for it to finish.
+      await tester.tap(find.byType(ElevatedButton));
+      await tester.pump();
+      await tester.pump(const Duration(milliseconds: 400));
+
+      // Check that the color has changed but not to the final color.
+      button = tester.widget(find.byType(ElevatedButton));
+      MaterialStateProperty<Color?>? changedColor =
+          button.style!.backgroundColor;
+      expect(initialColor, isNot(changedColor));
+
+      // Wait for the animation to finish.
+      await tester.pump(const Duration(milliseconds: 400));
+
+      // Check that the color has changed to the final color.
+      button = tester.widget(find.byType(ElevatedButton));
+      MaterialStateProperty<Color?>? finalColor = button.style!.backgroundColor;
+      expect(changedColor, isNot(finalColor));
+    });
+  });
+}