fix(flame_behaviors): make PropagatingCollisionBehavior more open (#42

)
VeryGoodOpenSource · May 11, 2023 · 4ae0553 · 4ae0553
1 parent 8ea3554
commit 4ae0553
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Showing 2 changed files with 47 additions and 9 deletions.
diff --git a/packages/flame_behaviors/lib/src/behaviors/propagating_collision_behavior.dart b/packages/flame_behaviors/lib/src/behaviors/propagating_collision_behavior.dart
@@ -9,7 +9,7 @@ import 'package:flutter/material.dart';
 /// the entity that is colliding with the [Parent] is an instance of [Collider].
 /// {@endtemplate}
 abstract class CollisionBehavior<Collider extends Component,
-    Parent extends PositionedEntity> extends Behavior<Parent> {
+    Parent extends EntityMixin> extends Behavior<Parent> {
   /// Check if the given component is an instance of [Collider].
   bool isValid(Component c) => c is Collider;
 
@@ -56,14 +56,26 @@ abstract class CollisionBehavior<Collider extends Component,
 /// **Note**: This behavior can also be used for collisions between entities
 /// and non-entity components, by passing the component's type as the
 /// `Collider` to the [CollisionBehavior].
+///
+/// The parent to which this behavior is added should be a [PositionComponent]
+/// that uses the [EntityMixin]. Flame behaviors comes with the
+/// [PositionedEntity] which does exactly that but any kind of position
+/// component will work.
 /// {@endtemplate}
-class PropagatingCollisionBehavior<Parent extends PositionedEntity>
+class PropagatingCollisionBehavior<Parent extends EntityMixin>
     extends Behavior<Parent> with CollisionCallbacks {
   /// {@macro propagating_collision_behavior}
   PropagatingCollisionBehavior(this._hitbox) : super(children: [_hitbox]);
 
   final ShapeHitbox _hitbox;
 
+  @override
+  @mustCallSuper
+  void onMount() {
+    assert(parent is PositionComponent, 'parent must be a PositionComponent');
+    super.onMount();
+  }
+
   @override
   Future<void> onLoad() async {
     _hitbox

diff --git a/packages/flame_behaviors/test/src/behaviors/propagating_collision_behavior_test.dart b/packages/flame_behaviors/test/src/behaviors/propagating_collision_behavior_test.dart
@@ -24,6 +24,10 @@ class _EntityC extends PositionedEntity {
   _EntityC() : super(size: Vector2.all(16));
 }
 
+class _EntityD extends Entity {
+  _EntityD();
+}
+
 abstract class _CollisionBehavior<A extends Component,
     B extends PositionedEntity> extends CollisionBehavior<A, B> {
   bool onCollisionStartCalled = false;
@@ -59,7 +63,7 @@ class _CollisionBehaviorAtoComponent
 void main() {
   final flameTester = FlameTester(TestGame.new);
 
-  group('CollisionBehavior', () {
+  group('$CollisionBehavior', () {
     flameTester.testGameWidget(
       'isColliding returns true if it is current colliding with the Collider',
       setUp: (game, tester) async {
@@ -119,35 +123,57 @@ void main() {
     );
   });
 
-  group('PropagatingCollisionBehavior', () {
+  group('$PropagatingCollisionBehavior', () {
     flameTester.testGameWidget(
       'can be added to an Entity',
       setUp: (game, tester) async {
-        final passableCollisionBehavior = PropagatingCollisionBehavior(
+        final propagatingCollisionBehavior = PropagatingCollisionBehavior(
           RectangleHitbox(),
         );
-        final entityA = _EntityA(behaviors: [passableCollisionBehavior]);
+        final entityA = _EntityA(behaviors: [propagatingCollisionBehavior]);
 
         await game.ensureAdd(entityA);
       },
       verify: (game, tester) async {
         final entityA = game.firstChild<_EntityA>()!;
-        final passableCollisionBehavior =
+        final propagatingCollisionBehavior =
             entityA.firstChild<PropagatingCollisionBehavior>()!;
 
         expect(
           entityA.findBehavior<PropagatingCollisionBehavior>(),
-          equals(passableCollisionBehavior),
+          equals(propagatingCollisionBehavior),
         );
         expect(
-          passableCollisionBehavior.children
+          propagatingCollisionBehavior.children
               .whereType<RectangleHitbox>()
               .length,
           equals(1),
         );
       },
     );
 
+    flameTester.testGameWidget(
+      'throws assertion exception if parent is not a positioned component',
+      setUp: (game, tester) async {
+        await game.ensureAdd(_EntityD());
+        return game.pauseEngine(); // Pausing engine to trigger it manually
+      },
+      verify: (game, tester) async {
+        final entity = game.firstChild<_EntityD>()!;
+        final propagatingCollisionBehavior = PropagatingCollisionBehavior(
+          RectangleHitbox(),
+        );
+
+        await expectLater(
+          () async {
+            await entity.add(propagatingCollisionBehavior);
+            game.update(0);
+          },
+          failsAssert('parent must be a PositionComponent'),
+        );
+      },
+    );
+
     group('propagates collision', () {
       flameTester.testGameWidget(
         'on start to the correct collision behavior',