refactor: removed verbose constructors

lib/game/components/board.dart

@@ -129,7 +129,7 @@ class _BottomGroupSide extends Component {
   Future<void> onLoad() async {
     final direction = _side.direction;
 
-    final flipper = Flipper.fromSide(
+    final flipper = Flipper(
       side: _side,
     )..initialPosition = _position;
     final baseboard = Baseboard(side: _side)

lib/game/components/flipper.dart

@@ -7,6 +7,16 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:pinball/game/game.dart';
 
+const _leftFlipperKeys = [
+  LogicalKeyboardKey.arrowLeft,
+  LogicalKeyboardKey.keyA,
+];
+
+const _rightFlipperKeys = [
+  LogicalKeyboardKey.arrowRight,
+  LogicalKeyboardKey.keyD,
+];
+
 /// {@template flipper}
 /// A bat, typically found in pairs at the bottom of the board.
 ///
@@ -14,47 +24,13 @@ import 'package:pinball/game/game.dart';
 /// {@endtemplate flipper}
 class Flipper extends BodyComponent with KeyboardHandler, InitialPosition {
   /// {@macro flipper}
-  Flipper._({
+  Flipper({
     required this.side,
-    required List<LogicalKeyboardKey> keys,
-  }) : _keys = keys {
+  }) : _keys = side.isLeft ? _leftFlipperKeys : _rightFlipperKeys {
     // TODO(alestiago): Remove paint with asset and size correctly.
     paint = Paint()..color = Colors.transparent;
   }
 
-  Flipper._left()
-      : this._(
-          side: BoardSide.left,
-          keys: [
-            LogicalKeyboardKey.arrowLeft,
-            LogicalKeyboardKey.keyA,
-          ],
-        );
-
-  Flipper._right()
-      : this._(
-          side: BoardSide.right,
-          keys: [
-            LogicalKeyboardKey.arrowRight,
-            LogicalKeyboardKey.keyD,
-          ],
-        );
-
-  /// Constructs a [Flipper] from a [BoardSide].
-  ///
-  /// A [Flipper._right] and [Flipper._left] besides being mirrored
-  /// horizontally, also have different [LogicalKeyboardKey]s that control them.
-  factory Flipper.fromSide({
-    required BoardSide side,
-  }) {
-    switch (side) {
-      case BoardSide.left:
-        return Flipper._left();
-      case BoardSide.right:
-        return Flipper._right();
-    }
-  }
-
   /// Asset location of the sprite that renders with the [Flipper].
   ///
   /// Sprite is preloaded by [PinballGameAssetsX].
@@ -251,10 +227,10 @@ class _FlipperAnchorRevoluteJointDef extends RevoluteJointDef {
     lowerAngle = upperAngle = angle;
   }
 
-  final BoardSide side;
-
   /// The total angle of the arc motion.
   static const _sweepingAngle = math.pi / 3.5;
+
+  final BoardSide side;
 }
 
 /// {@template flipper_anchor}

test/game/components/flipper_test.dart

@@ -21,10 +21,10 @@ void main() {
       flameTester.test(
         'loads correctly',
         (game) async {
-          final leftFlipper = Flipper.fromSide(
+          final leftFlipper = Flipper(
             side: BoardSide.left,
           );
-          final rightFlipper = Flipper.fromSide(
+          final rightFlipper = Flipper(
             side: BoardSide.right,
           );
           await game.ready();
@@ -37,13 +37,13 @@ void main() {
 
       group('constructor', () {
         test('sets BoardSide', () {
-          final leftFlipper = Flipper.fromSide(
+          final leftFlipper = Flipper(
             side: BoardSide.left,
           );
 
           expect(leftFlipper.side, equals(leftFlipper.side));
 
-          final rightFlipper = Flipper.fromSide(
+          final rightFlipper = Flipper(
             side: BoardSide.right,
           );
           expect(rightFlipper.side, equals(rightFlipper.side));
@@ -54,7 +54,7 @@ void main() {
         flameTester.test(
           'is dynamic',
           (game) async {
-            final flipper = Flipper.fromSide(
+            final flipper = Flipper(
               side: BoardSide.left,
             );
             await game.ensureAdd(flipper);
@@ -66,7 +66,7 @@ void main() {
         flameTester.test(
           'ignores gravity',
           (game) async {
-            final flipper = Flipper.fromSide(
+            final flipper = Flipper(
               side: BoardSide.left,
             );
             await game.ensureAdd(flipper);
@@ -78,7 +78,7 @@ void main() {
         flameTester.test(
           'has greater mass than Ball',
           (game) async {
-            final flipper = Flipper.fromSide(
+            final flipper = Flipper(
               side: BoardSide.left,
             );
             final ball = Ball();
@@ -98,7 +98,7 @@ void main() {
         flameTester.test(
           'has three',
           (game) async {
-            final flipper = Flipper.fromSide(
+            final flipper = Flipper(
               side: BoardSide.left,
             );
             await game.ensureAdd(flipper);
@@ -110,7 +110,7 @@ void main() {
         flameTester.test(
           'has density',
           (game) async {
-            final flipper = Flipper.fromSide(
+            final flipper = Flipper(
               side: BoardSide.left,
             );
             await game.ensureAdd(flipper);
@@ -140,7 +140,7 @@ void main() {
           late Flipper flipper;
 
           setUp(() {
-            flipper = Flipper.fromSide(
+            flipper = Flipper(
               side: BoardSide.left,
             );
           });
@@ -206,7 +206,7 @@ void main() {
           late Flipper flipper;
 
           setUp(() {
-            flipper = Flipper.fromSide(
+            flipper = Flipper(
               side: BoardSide.right,
             );
           });