Merge pull request GH-2 from gh/bowling-game

bowling game

lib/bowling_game.dart

@@ -0,0 +1,58 @@
+class BowlingGame {
+  static const _totalFrames = 10;
+  static const _allPins = 10;
+  static const _rollsInNormalFrame = 2;
+  static const _rollsInStrike = 1;
+
+  final List<int> _rolls = [];
+
+  void roll(int pins) => _rolls.add(pins);
+
+  int score() {
+    int total = 0;
+    int rollIndex = 0;
+
+    for (int frame = 0; frame < _totalFrames; frame++) {
+      if (_isStrike(rollIndex)) {
+        total += _strikeScore(rollIndex);
+        rollIndex += _rollsInStrike;
+      } else if (_isSpare(rollIndex)) {
+        total += _spareScore(rollIndex);
+        rollIndex += _rollsInNormalFrame;
+      } else {
+        total += _normalScore(rollIndex);
+        rollIndex += _rollsInNormalFrame;
+      }
+    }
+
+    return total;
+  }
+
+  int _strikeScore(int rollIndex) {
+    return _allPins + _nextTwoRollsBonus(rollIndex);
+  }
+
+  int _spareScore(int rollIndex) {
+    return _allPins + _nextRollBonus(rollIndex);
+  }
+
+  int _normalScore(int rollIndex) {
+    return _rolls[rollIndex] + _rolls[rollIndex + 1];
+  }
+
+  int _nextTwoRollsBonus(int rollIndex) {
+    return _rolls[rollIndex + 1] + _rolls[rollIndex + 2];
+  }
+
+  int _nextRollBonus(int rollIndex) {
+    return _rolls[rollIndex + 2];
+  }
+
+  bool _isSpare(int rollIndex) {
+    return _rolls[rollIndex] + _rolls[rollIndex + 1] == _allPins;
+  }
+
+  bool _isStrike(int rollIndex) {
+    return _rolls[rollIndex] == _allPins;
+  }
+}

test/bowling_game_test.dart

@@ -0,0 +1,78 @@
+import 'package:tdd_katas/bowling_game.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('Bowling Game Scoring', () {
+    late BowlingGame game;
+
+    setUp(() {
+      game = BowlingGame();
+    });
+
+    void rollMany(int times, int pins) {
+      for (int i = 0; i < times; i++) {
+        game.roll(pins);
+      }
+    }
+
+    group('Basic Scoring', () {
+      test('gutter game - no pins knocked', () {
+        rollMany(20, 0);
+        expect(game.score(), 0);
+      });
+
+      test('all ones - simple addition', () {
+        rollMany(20, 1);
+        expect(game.score(), 20);
+      });
+    });
+
+    group('Spare Bonus (next 1 roll)', () {
+      test('one spare in first frame', () {
+        game.roll(5);
+        game.roll(5); // spare
+        game.roll(3); // bonus for spare
+        rollMany(17, 0);
+
+        expect(game.score(), 16); // 10 + 3 (bonus) + 3
+      });
+
+      test('all spares with 5 pins each', () {
+        rollMany(21, 5); // 10 frames of 5,5 + 1 bonus roll
+        expect(game.score(), 150);
+      });
+    });
+
+    group('Strike Bonus (next 2 rolls)', () {
+      test('one strike in first frame', () {
+        game.roll(10); // Strike!
+        game.roll(3);
+        game.roll(4); // Next 2 rolls are bonus
+        rollMany(16, 0);
+
+        expect(game.score(), 24); // 10 + 3 + 4 (bonus) + 7
+      });
+
+      test('perfect game - twelve consecutive strikes', () {
+        rollMany(12, 10);
+        expect(game.score(), 300);
+      });
+    });
+
+    group('Complex Scenarios', () {
+      test('combination of strikes, spares, and normal frames', () {
+        game.roll(10); // Frame 1: Strike
+        game.roll(5);
+        game.roll(5); // Frame 2: Spare
+        game.roll(7);
+        game.roll(2); // Frame 3: Normal
+        rollMany(15, 0);
+
+        // Frame 1: 10 + 5 + 5 = 20
+        // Frame 2: 10 + 7 = 17
+        // Frame 3: 7 + 2 = 9
+        expect(game.score(), 46);
+      });
+    });
+  });
+}