Added test to ensure that ListMap.tail is O(1)

1 files changed, 7 insertions, 0 deletions

diff --git a/test/files/run/t6261.scala b/test/files/run/t6261.scala
index bf6d640de3..b4463256c9 100644
--- a/test/files/run/t6261.scala
+++ b/test/files/run/t6261.scala
@@ -2,6 +2,12 @@ import scala.collection.immutable._
 
 object Test extends App {
 
+  def test0() {
+    val m=ListMap(1->2,3->4)
+    if(m.tail ne m.tail)
+      println("ListMap.tail uses a builder, so it is not O(1)")
+  }
+
   def test1() {
     // test that a HashTrieMap with one leaf element is not created!
     val x = HashMap.empty + (1->1) + (2->2)
@@ -86,6 +92,7 @@ object Test extends App {
     // StructureTests.printStructure(z)
     require(z.size == 2 && z.contains(a._1) && z.contains(c._1))
   }
+  test0()
   test1()
   test2()
   test3()