added more test cases for class BitSet

2 files changed, 11 insertions, 5 deletions

diff --git a/src/library/scala/collection/BitSet.scala b/src/library/scala/collection/BitSet.scala
index 62d970c4b7..0952e01432 100644
--- a/src/library/scala/collection/BitSet.scala
+++ b/src/library/scala/collection/BitSet.scala
@@ -1,7 +1,7 @@
 /*                     __                                               *\
 **     ________ ___   / /  ___     Scala API                            **
 **    / __/ __// _ | / /  / _ |    (c) 2003-2007, LAMP/EPFL             **
-**  __\ \/ /__/ __ |/ /__/ __ |                                         **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
 ** /____/\___/_/ |_/____/_/ | |                                         **
 **                          |/                                          **
 \*                                                                      */
@@ -35,8 +35,13 @@ abstract class BitSet extends Set[Int] {
    *  @param i ...
    *  @return <code>true</code> if bit <code>i</code> is set.
    */
-  def contains(i: Int): Boolean =
-    (i < capacity) && ((arr(offset(i)) & mask(i)) != 0)
+  def contains(i: Int): Boolean = {
+    (i < capacity) && {
+      val j = offset(i)
+      (0 <= j) && (j < arr.length) &&
+      ((arr(j) & mask(i)) != 0)
+    }
+  }
 
   def capacity: Int
 
@@ -61,7 +66,8 @@ abstract class BitSet extends Set[Int] {
   def toArray: Array[Int] = {
     val length = memsize(capacity)
     val newarr = new Array[Int](length)
-    arraycopy(this.arr, 0, newarr, 0, length)
+    if (arr.length > 0)
+      arraycopy(this.arr, 0, newarr, 0, length)
     newarr
   }
 
diff --git a/src/library/scala/collection/immutable/BitSet.scala b/src/library/scala/collection/immutable/BitSet.scala
index 9dad0ba39e..946b75a406 100644
--- a/src/library/scala/collection/immutable/BitSet.scala
+++ b/src/library/scala/collection/immutable/BitSet.scala
@@ -40,7 +40,7 @@ class BitSet(val size: Int, val capacity: Int, ba: Array[Int], copy: Boolean)
   import compat.Platform.arraycopy
 
   protected val arr: Array[Int] = {
-    val ba1 = if (ba != null && ba.length > 0) ba else Array(0)
+    val ba1 = if (ba != null) ba else new Array[Int](0)
     if (copy) {
       val arr = new Array[Int](ba1.length)
       arraycopy(ba1, 0, arr, 0, ba1.length)