feat: removed friction from SlingShot

lib/game/components/sling_shot.dart

@@ -49,7 +49,8 @@ class SlingShot extends BodyComponent {
     }
 
     final triangle = PolygonShape()..set(triangleVertices);
-    fixtures.add(FixtureDef(triangle));
+    final triangleFixture = FixtureDef(triangle)..friction = 0;
+    fixtures.add(triangleFixture);
 
     final kicker = EdgeShape()
       ..set(
@@ -57,7 +58,9 @@ class SlingShot extends BodyComponent {
         triangleVertices.last,
       );
     // TODO(alestiago): Play with restitution value once game is bundled.
-    final kickerFixtureDef = FixtureDef(kicker)..restitution = 20.0;
+    final kickerFixtureDef = FixtureDef(kicker)
+      ..restitution = 20.0
+      ..friction = 0;
     fixtures.add(kickerFixtureDef);
 
     return fixtures;

test/game/components/sling_shot_test.dart

@@ -66,6 +66,17 @@ void main() {
           expect((fixture.shape as PolygonShape).vertices.length, equals(3));
         },
       );
+
+      flameTester.test(
+        'has no friction',
+        (game) async {
+          final slingShot = SlingShot(position: Vector2.zero());
+          await game.ensureAdd(slingShot);
+
+          final fixture = slingShot.body.fixtures[0];
+          expect(fixture.friction, equals(0));
+        },
+      );
     });
 
     group('second fixture', () {
@@ -100,6 +111,17 @@ void main() {
           expect(fixture.restitution, greaterThan(0));
         },
       );
+
+      flameTester.test(
+        'has no friction',
+        (game) async {
+          final slingShot = SlingShot(position: Vector2.zero());
+          await game.ensureAdd(slingShot);
+
+          final fixture = slingShot.body.fixtures[1];
+          expect(fixture.friction, equals(0));
+        },
+      );
     });
   });
 }