refactor: rename `SlingShot` to `Kicker` (#68)

* refactor: renamed SlingShot to Kicker

lib/game/components/board.dart

@@ -3,7 +3,7 @@ import 'package:pinball/game/game.dart';
 
 /// {@template board}
 /// The main flat surface of the [PinballGame], where the [Flipper]s,
-/// [RoundBumper]s, [SlingShot]s are arranged.
+/// [RoundBumper]s, [Kicker]s are arranged.
 /// {entemplate}
 class Board extends Component {
   /// {@macro board}
@@ -76,7 +76,7 @@ class _FlutterForest extends Component {
 /// {@template bottom_group}
 /// Grouping of the board's bottom [Component]s.
 ///
-/// The [_BottomGroup] consists of[Flipper]s, [Baseboard]s and [SlingShot]s.
+/// The [_BottomGroup] consists of[Flipper]s, [Baseboard]s and [Kicker]s.
 /// {@endtemplate}
 // TODO(alestiago): Consider renaming once entire Board is defined.
 class _BottomGroup extends Component {
@@ -138,14 +138,14 @@ class _BottomGroupSide extends Component {
             (Flipper.size.x * direction) - direction,
             Flipper.size.y,
           );
-    final slingShot = SlingShot(
+    final kicker = Kicker(
       side: _side,
     )..initialPosition = _position +
         Vector2(
           (Flipper.size.x) * direction,
-          Flipper.size.y + SlingShot.size.y,
+          Flipper.size.y + Kicker.size.y,
         );
 
-    await addAll([flipper, baseboard, slingShot]);
+    await addAll([flipper, baseboard, kicker]);
   }
 }

lib/game/components/board_side.dart

@@ -3,7 +3,7 @@ import 'package:pinball/game/game.dart';
 /// Indicates a side of the board.
 ///
 /// Usually used to position or mirror elements of a [PinballGame]; such as a
-/// [Flipper] or [SlingShot].
+/// [Flipper] or [Kicker].
 enum BoardSide {
   /// The left side of the board.
   left,

lib/game/components/components.dart

@@ -7,6 +7,7 @@ export 'flipper.dart';
 export 'initial_position.dart';
 export 'jetpack_ramp.dart';
 export 'joint_anchor.dart';
+export 'kicker.dart';
 export 'launcher_ramp.dart';
 export 'layer.dart';
 export 'pathway.dart';
@@ -14,6 +15,5 @@ export 'plunger.dart';
 export 'ramp_opening.dart';
 export 'round_bumper.dart';
 export 'score_points.dart';
-export 'sling_shot.dart';
 export 'spaceship.dart';
 export 'wall.dart';

lib/game/components/kicker.dart

@@ -6,15 +6,15 @@ import 'package:flutter/material.dart';
 import 'package:geometry/geometry.dart' as geometry show centroid;
 import 'package:pinball/game/game.dart';
 
-/// {@template sling_shot}
+/// {@template kicker}
 /// Triangular [BodyType.static] body that propels the [Ball] towards the
 /// opposite side.
 ///
-/// [SlingShot]s are usually positioned above each [Flipper].
-/// {@endtemplate sling_shot}
-class SlingShot extends BodyComponent with InitialPosition {
-  /// {@macro sling_shot}
-  SlingShot({
+/// [Kicker]s are usually positioned above each [Flipper].
+/// {@endtemplate kicker}
+class Kicker extends BodyComponent with InitialPosition {
+  /// {@macro kicker}
+  Kicker({
     required BoardSide side,
   }) : _side = side {
     // TODO(alestiago): Use sprite instead of color when provided.
@@ -23,14 +23,14 @@ class SlingShot extends BodyComponent with InitialPosition {
       ..style = PaintingStyle.fill;
   }
 
-  /// Whether the [SlingShot] is on the left or right side of the board.
+  /// Whether the [Kicker] is on the left or right side of the board.
   ///
-  /// A [SlingShot] with [BoardSide.left] propels the [Ball] to the right,
-  /// whereas a [SlingShot] with [BoardSide.right] propels the [Ball] to the
+  /// A [Kicker] with [BoardSide.left] propels the [Ball] to the right,
+  /// whereas a [Kicker] with [BoardSide.right] propels the [Ball] to the
   /// left.
   final BoardSide _side;
 
-  /// The size of the [SlingShot] body.
+  /// The size of the [Kicker] body.
   // TODO(alestiago): Use size from PositionedBodyComponent instead,
   // once a sprite is given.
   static final Vector2 size = Vector2(4, 10);
@@ -78,7 +78,7 @@ class SlingShot extends BodyComponent with InitialPosition {
     final bottomLineFixtureDef = FixtureDef(bottomEdge)..friction = 0;
     fixturesDefs.add(bottomLineFixtureDef);
 
-    final kickerEdge = EdgeShape()
+    final bouncyEdge = EdgeShape()
       ..set(
         upperCircle.position +
             Vector2(
@@ -92,11 +92,11 @@ class SlingShot extends BodyComponent with InitialPosition {
             ),
       );
 
-    final kickerFixtureDef = FixtureDef(kickerEdge)
+    final bouncyFixtureDef = FixtureDef(bouncyEdge)
       // TODO(alestiago): Play with restitution value once game is bundled.
       ..restitution = 10.0
       ..friction = 0;
-    fixturesDefs.add(kickerFixtureDef);
+    fixturesDefs.add(bouncyFixtureDef);
 
     // TODO(alestiago): Evaluate if there is value on centering the fixtures.
     final centroid = geometry.centroid(

test/game/components/board_test.dart

@@ -65,14 +65,14 @@ void main() {
       );
 
       flameTester.test(
-        'has two SlingShots',
+        'has two Kickers',
         (game) async {
           final board = Board(size: Vector2.all(500));
           await game.ready();
           await game.ensureAdd(board);
 
-          final slingShots = board.findNestedChildren<SlingShot>();
-          expect(slingShots.length, equals(2));
+          final kickers = board.findNestedChildren<Kicker>();
+          expect(kickers.length, equals(2));
         },
       );
 

test/game/components/kicker_test.dart

@@ -6,43 +6,43 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:pinball/game/game.dart';
 
 void main() {
-  group('SlingShot', () {
+  group('Kicker', () {
     // TODO(alestiago): Include golden tests for left and right.
     final flameTester = FlameTester(Forge2DGame.new);
 
     flameTester.test(
       'loads correctly',
       (game) async {
-        final slingShot = SlingShot(
+        final kicker = Kicker(
           side: BoardSide.left,
         );
-        await game.ensureAdd(slingShot);
+        await game.ensureAdd(kicker);
 
-        expect(game.contains(slingShot), isTrue);
+        expect(game.contains(kicker), isTrue);
       },
     );
 
     flameTester.test(
       'body is static',
       (game) async {
-        final slingShot = SlingShot(
+        final kicker = Kicker(
           side: BoardSide.left,
         );
-        await game.ensureAdd(slingShot);
+        await game.ensureAdd(kicker);
 
-        expect(slingShot.body.bodyType, equals(BodyType.static));
+        expect(kicker.body.bodyType, equals(BodyType.static));
       },
     );
 
     flameTester.test(
       'has restitution',
       (game) async {
-        final slingShot = SlingShot(
+        final kicker = Kicker(
           side: BoardSide.left,
         );
-        await game.ensureAdd(slingShot);
+        await game.ensureAdd(kicker);
 
-        final totalRestitution = slingShot.body.fixtures.fold<double>(
+        final totalRestitution = kicker.body.fixtures.fold<double>(
           0,
           (total, fixture) => total + fixture.restitution,
         );
@@ -53,12 +53,12 @@ void main() {
     flameTester.test(
       'has no friction',
       (game) async {
-        final slingShot = SlingShot(
+        final kicker = Kicker(
           side: BoardSide.left,
         );
-        await game.ensureAdd(slingShot);
+        await game.ensureAdd(kicker);
 
-        final totalFriction = slingShot.body.fixtures.fold<double>(
+        final totalFriction = kicker.body.fixtures.fold<double>(
           0,
           (total, fixture) => total + fixture.friction,
         );