Refactor threes with Roll

src/main/java/io/takima/Yatzy.java

@@ -20,31 +20,15 @@ public final class Yatzy {
     }
 
     public static int ones(Roll roll) {
-        return roll.toStream().filter(i -> i == 1).sum();
+        return roll.toStream().filter(dice -> dice == 1).sum();
     }
 
     public static int twos(Roll roll) {
-        return roll.toStream().filter(i -> i == 2).sum();
+        return roll.toStream().filter(dice -> dice == 2).sum();
     }
 
-    public static int threes(int d1, int d2, int d3, int d4, int d5) {
-        int s = 0;
-        if (d1 == 3) {
-            s += 3;
-        }
-        if (d2 == 3) {
-            s += 3;
-        }
-        if (d3 == 3) {
-            s += 3;
-        }
-        if (d4 == 3) {
-            s += 3;
-        }
-        if (d5 == 3) {
-            s += 3;
-        }
-        return s;
+    public static int threes(Roll roll) {
+        return roll.toStream().filter(dice -> dice == 3).sum();
     }
 
     public static int pair(int d1, int d2, int d3, int d4, int d5) {

src/test/java/io/takima/YatzyTest.java

@@ -49,8 +49,8 @@ class YatzyTest {
     @Test
     void threesShouldSumAllThreeDices() {
         assertAll(
-            () -> assertEquals(6, Yatzy.threes(1, 2, 3, 2, 3)),
-            () -> assertEquals(12, Yatzy.threes(2, 3, 3, 3, 3))
+            () -> assertEquals(6, Yatzy.threes(roll(1, 2, 3, 2, 3))),
+            () -> assertEquals(12, Yatzy.threes(roll(2, 3, 3, 3, 3)))
         );
     }