implement spare and strike

src/main/java/de/tealfire/Bowling.java

@@ -1,15 +1,53 @@
 package de.tealfire;
 
 public class Bowling {
-    int score = 0;
-    int roll = 0;
+    int[] rolls = new int[21];
+
+    int currentRoll = 0;
 
     public void roll(int i) {
-        score += i;
-        roll++;
+        rolls[currentRoll] = i;
+        currentRoll++;
     }
 
     public int score() {
+        int score = 0;
+        int frameIndex = 0;
+        for (int frame = 0; frame < 10; frame++) {
+            if (isStrike(frameIndex)) {
+                score += 10 + strikeBonus(frameIndex);
+                frameIndex++;
+            } else if (isSpare(frameIndex)) {
+                score += 10 + spareBonus(frameIndex);
+                frameIndex += 2;
+            } else {
+                score += sumOfBallsInFrame(frameIndex);
+                frameIndex += 2;
+            }
+        }
         return score;
     }
+
+    private boolean isStrike(int frameIndex) {
+        return rolls[frameIndex] == 10;
+    }
+
+    private int strikeBonus(int frameIndex) {
+        return rolls[frameIndex + 1] + rolls[frameIndex + 2];
+    }
+
+    private boolean isSpare(int frameIndex) {
+        return rolls[frameIndex] + rolls[frameIndex + 1] == 10;
+    }
+
+    private int spareBonus(int frameIndex) {
+        return rolls[frameIndex + 2];
+    }
+
+    private int sumOfBallsInFrame(int frameIndex) {
+        return rolls[frameIndex] + rolls[frameIndex + 1];
+    }
+    public void reset() {
+        currentRoll = 0;
+    }
 }

src/test/java/de/tealfire/BowlingTest.java

@@ -12,17 +12,29 @@ public class BowlingTest {
 
     @Test
     public void testScoreGutterGame() {
-        for (int i = 0; i < 20; i++) {
-            bowling.roll(0);
-        }
+        roll(20, 0);
         assert bowling.score() == 0;
     }
 
     @Test
     public void testScoreGameOfOnes() {
-        for (int i = 0; i < 20; i++) {
-            bowling.roll(1);
-        }
+        roll(20, 1);
         assert bowling.score() == 20;
     }
+
+    private void roll(int n, int pins) {
+        for (int i = 0; i < n; i++) {
+            bowling.roll(pins);
+        }
+    }
+
+    @Test
+    public void testScoreSpare() {
+        bowling.roll(5);
+        bowling.roll(5);
+        bowling.roll(3);
+        roll(17, 0);
+        assert bowling.score() == 16;
+    }
+
 }