feat: tested and improved GameEvent

lib/game/bloc/game_event.dart

@@ -5,12 +5,16 @@ abstract class GameEvent {
   const GameEvent();
 }
 
+/// Event added when a user drops a ball off the screen.
 class BallLost extends GameEvent {
   const BallLost();
 }
 
+/// Event added when a user increases it's score.
 class Scored extends GameEvent {
-  const Scored(this.points);
+  const Scored({
+    required this.points,
+  }) : assert(points > 0, 'Points must be greater than 0');
 
   final int points;
 }

test/game/bloc/game_event_test.dart

@@ -0,0 +1,24 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pinball/game/game.dart';
+
+void main() {
+  group('GameEvent', () {
+    group('BallLost', () {
+      test('BallLost can be instantiated', () {
+        expect(const BallLost(), isNotNull);
+      });
+    });
+
+    group('Scored', () {
+      test('Scored can be instantiated', () {
+        expect(const Scored(points: 1), isNotNull);
+      });
+
+      test(
+          'throws AssertionError '
+          'when score is smaller than 1', () {
+        expect(() => Scored(points: 0), throwsAssertionError);
+      });
+    });
+  });
+}