feat: tested and improved GameState

lib/game/bloc/game_state.dart

@@ -26,6 +26,11 @@ class GameState extends Equatable {
     int? score,
     int? balls,
   }) {
+    assert(
+      score == null || score >= this.score,
+      "Score can't be decreased",
+    );
+
     return GameState(
       score: score ?? this.score,
       balls: balls ?? this.balls,

test/game/bloc/game_state_test.dart

@@ -37,27 +37,83 @@ void main() {
         );
       },
     );
-  });
 
-  group('isGameOver', () {
+    group('isGameOver', () {
-    test(
+      test(
-        'is true '
+          'is true '
-        'when no balls are left', () {
+          'when no balls are left', () {
-      const gameState = GameState(
+        const gameState = GameState(
-        balls: 0,
+          balls: 0,
-        score: 0,
+          score: 0,
-      );
+        );
-      expect(gameState.isGameOver, isTrue);
+        expect(gameState.isGameOver, isTrue);
+      });
+
+      test(
+          'is false '
+          'when one 1 ball left', () {
+        const gameState = GameState(
+          balls: 1,
+          score: 0,
+        );
+        expect(gameState.isGameOver, isFalse);
+      });
     });
 
-    test(
+    group('copyWith', () {
-        'is false '
+      test(
-        'when one 1 ball left', () {
+        'throws AssertionError '
-      const gameState = GameState(
+        'when scored is decreased',
-        balls: 1,
+        () {
-        score: 0,
+          const gameState = GameState(
+            balls: 0,
+            score: 2,
+          );
+          expect(
+            () => gameState.copyWith(score: gameState.score - 1),
+            throwsAssertionError,
+          );
+        },
+      );
+
+      test(
+        'copies correctly '
+        'when no arguement specified',
+        () {
+          const gameState = GameState(
+            balls: 0,
+            score: 2,
+          );
+          expect(
+            gameState.copyWith(),
+            equals(gameState),
+          );
+        },
+      );
+
+      test(
+        'copies correctly '
+        'when all arguements specified',
+        () {
+          const gameState = GameState(
+            score: 2,
+            balls: 0,
+          );
+          final otherGameState = GameState(
+            score: gameState.score + 1,
+            balls: gameState.balls + 1,
+          );
+          expect(gameState, isNot(otherGameState));
+
+          expect(
+            gameState.copyWith(
+              score: otherGameState.score,
+              balls: otherGameState.balls,
+            ),
+            equals(otherGameState),
+          );
+        },
       );
-      expect(gameState.isGameOver, isFalse);
     });
   });
 }