Change leap to stateless (issue #353)

Author: zombiefungus

exercises/leap/example.scala

@@ -1,5 +1,6 @@
-case class Year(year: Int) {
-  lazy val isLeap: Boolean = divisibleBy(4) && (divisibleBy(400) || !divisibleBy(100))
+object Year {
+  def isLeap(year: Int): Boolean =
+    divisibleBy(year, 4) && (divisibleBy(year, 400) || !divisibleBy(year, 100))
 
-  private def divisibleBy(i: Int) = year % i == 0
+  private def divisibleBy(year: Int, i: Int) = year % i == 0
 }

exercises/leap/src/main/scala/Leap.scala

@@ -0,0 +1,3 @@
+object Year {
+  def isLeap(year: Int): Boolean = ???
+}

exercises/leap/src/test/scala/LeapTest.scala

@@ -2,31 +2,31 @@ import org.scalatest._
 
 class LeapTest extends FunSuite {
   test ("vanilla leap year") {
-    assert(Year(1996).isLeap)
+    assert(Year.isLeap(1996))
   }
 
   test ("any old year") {
     pending
-    assert(!Year(1997).isLeap)
+    assert(!Year.isLeap(1997))
   }
 
   test("an even year") {
     pending
-    assert(!Year(1986).isLeap)
+    assert(!Year.isLeap(1986))
   }
 
   test ("century") {
     pending
-    assert(!Year(1900).isLeap)
+    assert(!Year.isLeap(1900))
   }
 
   test ("exceptional century") {
     pending
-    assert(Year(2000).isLeap)
+    assert(Year.isLeap(2000))
   }
 
   test("exceptional century that is no millenium") {
     pending
-    assert(Year(1600).isLeap)
+    assert(Year.isLeap(1600))
   }
 }