fix: flaky FireEffect test (#124)

* refactor: migrated to ParticleSystemComponent

* refactor: simplified tests

* feat: forced min count to be 1

* feat: adjusted priorities

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

@@ -83,8 +83,9 @@ class Ball<T extends Forge2DGame> extends BodyComponent<T>
       final direction = body.linearVelocity.normalized();
       final effect = FireEffect(
         burstPower: _boostTimer,
-        direction: direction,
-        position: body.position,
+        direction: -direction,
+        position: Vector2(body.position.x, -body.position.y),
+        priority: priority - 1,
       );
 
       unawaited(gameRef.add(effect));

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

@@ -1,5 +1,6 @@
 import 'dart:math' as math;
 
+import 'package:flame/components.dart';
 import 'package:flame/extensions.dart';
 import 'package:flame/particles.dart';
 import 'package:flame_forge2d/flame_forge2d.dart' hide Particle;
@@ -19,33 +20,24 @@ const _particleRadius = 0.25;
 /// A [BodyComponent] which creates a fire trail effect using the given
 /// parameters
 /// {@endtemplate}
-class FireEffect extends BodyComponent {
+class FireEffect extends ParticleSystemComponent {
   /// {@macro fire_effect}
   FireEffect({
     required this.burstPower,
-    required this.position,
     required this.direction,
-  });
+    Vector2? position,
+    int? priority,
+  }) : super(
+          position: position,
+          priority: priority,
+        );
 
   /// A [double] value that will define how "strong" the burst of particles
-  /// will be
+  /// will be.
   final double burstPower;
 
-  /// The position of the burst
-  final Vector2 position;
-
-  /// Which direction the burst will aim
+  /// Which direction the burst will aim.
   final Vector2 direction;
-  late Particle _particle;
-
-  @override
-  Body createBody() {
-    final bodyDef = BodyDef()..position = position;
-
-    final fixtureDef = FixtureDef(CircleShape()..radius = 0)..isSensor = true;
-
-    return world.createBody(bodyDef)..createFixture(fixtureDef);
-  }
 
   @override
   Future<void> onLoad() async {
@@ -71,15 +63,15 @@ class FireEffect extends BodyComponent {
         );
       }),
     ];
-    final rng = math.Random();
+    final random = math.Random();
     final spreadTween = Tween<double>(begin: -0.2, end: 0.2);
 
-    _particle = Particle.generate(
-      count: (rng.nextDouble() * (burstPower * 10)).toInt(),
+    particle = Particle.generate(
+      count: math.max((random.nextDouble() * (burstPower * 10)).toInt(), 1),
       generator: (_) {
         final spread = Vector2(
-          spreadTween.transform(rng.nextDouble()),
-          spreadTween.transform(rng.nextDouble()),
+          spreadTween.transform(random.nextDouble()),
+          spreadTween.transform(random.nextDouble()),
         );
         final finalDirection = Vector2(direction.x, -direction.y) + spread;
         final speed = finalDirection * (burstPower * 20);
@@ -88,26 +80,9 @@ class FireEffect extends BodyComponent {
           lifespan: 5 / burstPower,
           position: Vector2.zero(),
           speed: speed,
-          child: children[rng.nextInt(children.length)],
+          child: children[random.nextInt(children.length)],
         );
       },
     );
   }
-
-  @override
-  void update(double dt) {
-    super.update(dt);
-    _particle.update(dt);
-
-    if (_particle.shouldRemove) {
-      removeFromParent();
-    }
-  }
-
-  @override
-  void render(Canvas canvas) {
-    super.render(canvas);
-
-    _particle.render(canvas);
-  }
 }

packages/pinball_components/sandbox/lib/stories/effects/fire_effect.dart

@@ -34,7 +34,6 @@ class _EffectEmitter extends Component {
       add(
         FireEffect(
           burstPower: (_timer / _timerLimit) * _force,
-          position: Vector2.zero(),
           direction: _direction,
         ),
       );

packages/pinball_components/test/helpers/mocks.dart

@@ -1,12 +1,8 @@
-import 'dart:ui';
-
 import 'package:flame/components.dart';
 import 'package:flame_forge2d/flame_forge2d.dart';
 import 'package:mocktail/mocktail.dart';
 import 'package:pinball_components/pinball_components.dart';
 
-class MockCanvas extends Mock implements Canvas {}
-
 class MockFilter extends Mock implements Filter {}
 
 class MockFixture extends Mock implements Fixture {}

packages/pinball_components/test/src/components/fire_effect_test.dart

@@ -1,11 +1,8 @@
 // ignore_for_file: cascade_invocations
 
-import 'dart:ui';
-
 import 'package:flame/components.dart';
 import 'package:flame_test/flame_test.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mocktail/mocktail.dart';
 import 'package:pinball_components/pinball_components.dart';
 
 import '../../helpers/helpers.dart';
@@ -14,43 +11,16 @@ void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
   final flameTester = FlameTester(TestGame.new);
 
-  setUpAll(() {
-    registerFallbackValue(Offset.zero);
-    registerFallbackValue(Paint());
-  });
-
-  group('FireEffect', () {
-    flameTester.test('is removed once its particles are done', (game) async {
-      await game.ensureAdd(
-        FireEffect(
-          burstPower: 1,
-          position: Vector2.zero(),
-          direction: Vector2.all(2),
-        ),
-      );
-      await game.ready();
-      expect(game.children.whereType<FireEffect>().length, equals(1));
-      game.update(5);
-
-      await game.ready();
-      expect(game.children.whereType<FireEffect>().length, equals(0));
-    });
-
-    flameTester.test('render circles on the canvas', (game) async {
-      final effect = FireEffect(
+  flameTester.test(
+    'loads correctly',
+    (game) async {
+      final fireEffect = FireEffect(
         burstPower: 1,
-        position: Vector2.zero(),
-        direction: Vector2.all(2),
+        direction: Vector2.zero(),
       );
-      await game.ensureAdd(effect);
-      await game.ready();
-
-      final canvas = MockCanvas();
-      effect.render(canvas);
+      await game.ensureAdd(fireEffect);
 
-      verify(() => canvas.drawCircle(any(), any(), any())).called(
-        greaterThan(0),
-      );
-    });
-  });
+      expect(game.contains(fireEffect), isTrue);
+    },
+  );
 }