refactor: moved scaling to `BallScalingBehavior`

packages/pinball_components/lib/src/components/ball/ball.dart

@@ -1,6 +1,5 @@
 import 'dart:async';
 import 'dart:math' as math;
-import 'dart:ui';
 
 import 'package:flame/components.dart';
 import 'package:flame_forge2d/flame_forge2d.dart';
@@ -32,6 +31,16 @@ class Ball<T extends Forge2DGame> extends BodyComponent<T>
     layer = Layer.board;
   }
 
+  /// Creates a [Ball] without any behaviors.
+  ///
+  /// This can be used for testing [Ball]'s behaviors in isolation.
+  @visibleForTesting
+  Ball.test()
+      : baseColor = const Color(0xFFFFFFFF),
+        super(
+          children: [_BallSpriteComponent()],
+        );
+
   /// The size of the [Ball].
   static final Vector2 size = Vector2.all(4.13);
 

packages/pinball_components/lib/src/components/ball/behaviors/ball_scaling_behavior.dart

@@ -16,6 +16,8 @@ class BallScalingBehavior extends Component with ParentIsA<Ball> {
 
     parent.body.fixtures.first.shape.radius = (Ball.size.x / 2) * scaleFactor;
 
-    parent.firstChild<SpriteComponent>()!.scale = Vector2.all(scaleFactor);
+    parent.firstChild<SpriteComponent>()!.scale.setFrom(
+          Vector2.all(scaleFactor),
+        );
   }
 }

packages/pinball_components/test/src/components/ball/ball_test.dart

@@ -6,8 +6,9 @@ import 'package:flame_test/flame_test.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:pinball_components/pinball_components.dart';
+import 'package:pinball_components/src/components/ball/behaviors/behaviors.dart';
 
-import '../../helpers/helpers.dart';
+import '../../../helpers/helpers.dart';
 
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
@@ -25,6 +26,15 @@ void main() {
       },
     );
 
+    flameTester.test('add a BallScalingBehavior', (game) async {
+      final ball = Ball(baseColor: Colors.blue);
+      await game.ensureAdd(ball);
+      expect(
+        ball.descendants().whereType<BallScalingBehavior>().length,
+        equals(1),
+      );
+    });
+
     group('body', () {
       flameTester.test(
         'is dynamic',
@@ -116,19 +126,6 @@ void main() {
           expect(ball.body.position, equals(ball.initialPosition));
         });
       });
-
-      // TODO(allisonryan0002): delete or retest this if/when solution is added
-      // to prevent forces on a ball while stopped.
-
-      // flameTester.test('by applying velocity', (game) async {
-      //   final ball = Ball(baseColor: Colors.blue);
-      //   await game.ensureAdd(ball);
-      //   ball.stop();
-
-      //   ball.body.linearVelocity.setValues(10, 10);
-      //   game.update(1);
-      //   expect(ball.body.position, equals(ball.initialPosition));
-      // });
     });
 
     group('resume', () {