feat: writing tests

test/game/pinball_game_test.dart

@@ -1,6 +1,7 @@
 // ignore_for_file: cascade_invocations
 
 import 'package:flame/components.dart';
+import 'package:flame/game.dart';
 import 'package:flame_test/flame_test.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:mocktail/mocktail.dart';
@@ -60,6 +61,13 @@ void main() {
           equals(1),
         );
       });
+
+      group('controller', () {
+        // TODO(alestiago): Write test to be controller agnostic.
+        group('listenWhen', () {
+          flameTester.test('when a ball is lost', (game) async {});
+        });
+      });
     });
 
     debugModeFlameTester.test('adds a ball on tap up', (game) async {