Add test for tuple split

Author: Antoine Brunner

library/src/scala/runtime/DynamicTuple.scala

@@ -301,18 +301,21 @@ object DynamicTuple {
   }
 
   def dynamicSplitAt[This <: Tuple, N <: Int](self: This, n: N): Split[This, N] = {
+    if (n < 0) throw new IndexOutOfBoundsException(n.toString)
+    val size = self.size
+    val actualN = Math.min(n, size)
+
     type Result = Split[This, N]
     val (arr1, arr2) = (self: Any) match {
       case () => (Array.empty[Object], Array.empty[Object])
       case xxl: TupleXXL =>
-        xxl.elems.asInstanceOf[Array[Object]].splitAt(n)
+        xxl.elems.asInstanceOf[Array[Object]].splitAt(actualN)
       case _ =>
-        val size = self.asInstanceOf[Product].productArity
-        val arr1 = new Array[Object](n)
-        val arr2 = new Array[Object](size - n)
+        val arr1 = new Array[Object](actualN)
+        val arr2 = new Array[Object](size - actualN)
         val it = self.asInstanceOf[Product].productIterator
-        itToArray(it, n, arr1, 0)
-        itToArray(it, size - n, arr2, 0)
+        itToArray(it, actualN, arr1, 0)
+        itToArray(it, size - actualN, arr2, 0)
         (arr1, arr2)
     }
     (

tests/run/tuple-split.check

@@ -0,0 +1,15 @@
+((),())
+((),())
+((),())
+((),())
+((),(1,2,3,4,5))
+((1),(2,3,4,5))
+((1,2,3),(4,5))
+((1,2,3,4,5),())
+((1,2,3,4,5),())
+((),(11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35))
+((11),(12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35))
+((11,12,13,14,15,16,17,18,19,20),(21,22,23,24,25,26,27,28,29,30,31,32,33,34,35))
+((11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30),(31,32,33,34,35))
+((11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35),())
+((11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35),())

tests/run/tuple-split.scala

@@ -0,0 +1,24 @@
+
+object Test extends App {
+  val emptyTuple: Tuple = ()
+  val tuple: Tuple = ("1", "2", "3", "4", "5")
+  val tupleXXL: Tuple = ("11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35")
+
+  println(emptyTuple.splitAt(0))
+  println(emptyTuple.splitAt(0))
+  println(emptyTuple.splitAt(1))
+  println(emptyTuple.splitAt(10))
+
+  println(tuple.splitAt(0))
+  println(tuple.splitAt(1))
+  println(tuple.splitAt(3))
+  println(tuple.splitAt(5))
+  println(tuple.splitAt(10))
+
+  println(tupleXXL.splitAt(0))
+  println(tupleXXL.splitAt(1))
+  println(tupleXXL.splitAt(10))
+  println(tupleXXL.splitAt(20))
+  println(tupleXXL.splitAt(25))
+  println(tupleXXL.splitAt(30))
+}