feat: made Flipper use InitialPosition

lib/game/components/board.dart

@@ -59,8 +59,7 @@ class _BottomGroupSide extends Component {
 
     final flipper = Flipper.fromSide(
       side: _side,
-      position: _position,
-    );
+    )..initialPosition = _position;
     final baseboard = Baseboard(side: _side)
       ..initialPosition = _position +
           Vector2(

lib/game/components/flipper.dart

@@ -13,19 +13,15 @@ import 'package:pinball/game/game.dart';
 ///
 /// [Flipper] can be controlled by the player in an arc motion.
 /// {@endtemplate flipper}
-class Flipper extends BodyComponent with KeyboardHandler {
+class Flipper extends BodyComponent with KeyboardHandler, InitialPosition {
   /// {@macro flipper}
   Flipper._({
-    required Vector2 position,
     required this.side,
     required List<LogicalKeyboardKey> keys,
-  })  : _position = position,
-        _keys = keys;
+  }) : _keys = keys;
 
-  Flipper._left({
-    required Vector2 position,
-  }) : this._(
-          position: position,
+  Flipper._left()
+      : this._(
           side: BoardSide.left,
           keys: [
             LogicalKeyboardKey.arrowLeft,
@@ -33,10 +29,8 @@ class Flipper extends BodyComponent with KeyboardHandler {
           ],
         );
 
-  Flipper._right({
-    required Vector2 position,
-  }) : this._(
-          position: position,
+  Flipper._right()
+      : this._(
           side: BoardSide.right,
           keys: [
             LogicalKeyboardKey.arrowRight,
@@ -50,13 +44,12 @@ class Flipper extends BodyComponent with KeyboardHandler {
   /// horizontally, also have different [LogicalKeyboardKey]s that control them.
   factory Flipper.fromSide({
     required BoardSide side,
-    required Vector2 position,
   }) {
     switch (side) {
       case BoardSide.left:
-        return Flipper._left(position: position);
+        return Flipper._left();
       case BoardSide.right:
-        return Flipper._right(position: position);
+        return Flipper._right();
     }
   }
 
@@ -82,9 +75,6 @@ class Flipper extends BodyComponent with KeyboardHandler {
   /// whereas a [Flipper] with [BoardSide.right] has a clockwise arc motion.
   final BoardSide side;
 
-  /// The initial position of the [Flipper] body.
-  final Vector2 _position;
-
   /// The [LogicalKeyboardKey]s that will control the [Flipper].
   ///
   /// [onKeyEvent] method listens to when one of these keys is pressed.
@@ -201,7 +191,7 @@ class Flipper extends BodyComponent with KeyboardHandler {
     final bodyDef = BodyDef()
       ..gravityScale = 0
       ..type = BodyType.dynamic
-      ..position = _position;
+      ..position = initialPosition;
 
     final body = world.createBody(bodyDef);
     _createFixtureDefs().forEach(body.createFixture);

test/game/components/flipper_test.dart

@@ -22,12 +22,10 @@ void main() {
         (game) async {
           final leftFlipper = Flipper.fromSide(
             side: BoardSide.left,
-            position: Vector2.zero(),
-          );
+          )..initialPosition = Vector2.zero();
           final rightFlipper = Flipper.fromSide(
             side: BoardSide.right,
-            position: Vector2.zero(),
-          );
+          )..initialPosition = Vector2.zero();
           await game.ready();
           await game.ensureAddAll([leftFlipper, rightFlipper]);
 
@@ -40,15 +38,13 @@ void main() {
         test('sets BoardSide', () {
           final leftFlipper = Flipper.fromSide(
             side: BoardSide.left,
-            position: Vector2.zero(),
-          );
+          )..initialPosition = Vector2.zero();
 
           expect(leftFlipper.side, equals(leftFlipper.side));
 
           final rightFlipper = Flipper.fromSide(
             side: BoardSide.right,
-            position: Vector2.zero(),
-          );
+          )..initialPosition = Vector2.zero();
           expect(rightFlipper.side, equals(rightFlipper.side));
         });
       });
@@ -60,8 +56,7 @@ void main() {
             final position = Vector2.all(10);
             final flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: position,
-            );
+            )..initialPosition = position;
             await game.ensureAdd(flipper);
             game.contains(flipper);
 
@@ -74,8 +69,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             await game.ensureAdd(flipper);
 
             expect(flipper.body.bodyType, equals(BodyType.dynamic));
@@ -87,8 +81,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             await game.ensureAdd(flipper);
 
             expect(flipper.body.gravityScale, isZero);
@@ -100,8 +93,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             final ball = Ball(position: Vector2.zero());
 
             await game.ready();
@@ -121,8 +113,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             await game.ensureAdd(flipper);
 
             expect(flipper.body.fixtures.length, equals(3));
@@ -134,8 +125,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             await game.ensureAdd(flipper);
 
             final fixtures = flipper.body.fixtures;
@@ -165,8 +155,7 @@ void main() {
           setUp(() {
             flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
           });
 
           testRawKeyDownEvents(leftKeys, (event) {
@@ -232,8 +221,7 @@ void main() {
           setUp(() {
             flipper = Flipper.fromSide(
               side: BoardSide.right,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
           });
 
           testRawKeyDownEvents(rightKeys, (event) {
@@ -302,8 +290,7 @@ void main() {
       (game) async {
         final flipper = Flipper.fromSide(
           side: BoardSide.left,
-          position: Vector2.zero(),
-        );
+        )..initialPosition = Vector2.zero();
         await game.ensureAdd(flipper);
 
         final flipperAnchor = FlipperAnchor(flipper: flipper);
@@ -318,8 +305,7 @@ void main() {
       (game) async {
         final flipper = Flipper.fromSide(
           side: BoardSide.right,
-          position: Vector2.zero(),
-        );
+        )..initialPosition = Vector2.zero();
         await game.ensureAdd(flipper);
 
         final flipperAnchor = FlipperAnchor(flipper: flipper);
@@ -337,8 +323,7 @@ void main() {
         (game) async {
           final flipper = Flipper.fromSide(
             side: BoardSide.left,
-            position: Vector2.zero(),
-          );
+          )..initialPosition = Vector2.zero();
           await game.ensureAdd(flipper);
 
           final flipperAnchor = FlipperAnchor(flipper: flipper);
@@ -359,8 +344,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             await game.ensureAdd(flipper);
 
             final flipperAnchor = FlipperAnchor(flipper: flipper);
@@ -380,8 +364,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.right,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             await game.ensureAdd(flipper);
 
             final flipperAnchor = FlipperAnchor(flipper: flipper);
@@ -406,8 +389,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.left,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             await game.ensureAdd(flipper);
 
             final flipperAnchor = FlipperAnchor(flipper: flipper);
@@ -433,8 +415,7 @@ void main() {
           (game) async {
             final flipper = Flipper.fromSide(
               side: BoardSide.right,
-              position: Vector2.zero(),
-            );
+            )..initialPosition = Vector2.zero();
             await game.ensureAdd(flipper);
 
             final flipperAnchor = FlipperAnchor(flipper: flipper);