added test case for #2417. no review

git-svn-id: http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk@21200 5e8d7ff9-d8ef-0310-90f0-a4852d11357a

test/files/run/t2417.check

@@ -0,0 +1,12 @@
+testing small Map that doesn't promote to HashMap...
+
+testing single-threaded HashMap use...
+
+testing HashMap.size from multiple threads...
+
+testing small Set that doesn't promote to HashSet...
+
+testing single-threaded HashSet use...
+
+testing HashSet.size from multiple threads...
+

test/files/run/t2417.scala

@@ -0,0 +1,77 @@
+// #2417
+object Test {
+  
+  def parallel(numThreads: Int)(block: => Unit) {
+    var failure: Throwable = null
+    val threads = Array.fromFunction(i => new Thread {
+      override def run {
+        try {
+          block
+          } catch {
+            case x => failure = x
+          }
+        }
+      })(numThreads)
+      for (t <- threads) t.start
+      for (t <- threads) t.join
+      if (failure != null) println("FAILURE: " + failure)
+    }
+  
+    def testSet(initialSize: Int, numThreads: Int, passes: Int) {
+      val orig = Set.empty ++ (1 to initialSize)
+      parallel(numThreads) {
+        for (pass <- 0 until passes) {
+          var s = orig
+          for (e <- (initialSize to 1 by -1)) {
+            s -= e
+            val obs = s.size
+            if (obs != e - 1) {
+              throw new Exception("removed e=" + e + ", size was " + obs + ", s=" + s)
+            }
+          }
+        }
+      }
+    }
+  
+    def testMap(initialSize: Int, numThreads: Int, passes: Int) {
+      val orig = Map.empty ++ ((1 to initialSize) map ((_,"v")))
+      parallel(numThreads) {
+        for (pass <- 0 until passes) {
+          var m = orig
+          for (e <- (initialSize to 1 by -1)) {
+            m -= e
+            val obs = m.size
+            if (obs != e - 1) {
+              throw new Exception("removed e=" + e + ", size was " + obs + ", m=" + m)
+            }
+          }
+        }
+      }
+    }
+  
+    def main(args: Array[String]) {
+      println("testing small Map that doesn't promote to HashMap...")
+      testMap(4, 2, 1000000)
+      println()
+  
+      println("testing single-threaded HashMap use...")
+      testMap(5, 1, 1000000)
+      println()
+  
+      println("testing HashMap.size from multiple threads...")
+      testMap(5, 2, 1000000)
+      println()
+  
+      println("testing small Set that doesn't promote to HashSet...")
+      testSet(4, 2, 1000000)
+      println()
+  
+      println("testing single-threaded HashSet use...")
+      testSet(5, 1, 1000000)
+      println()
+  
+      println("testing HashSet.size from multiple threads...")
+      testSet(5, 2, 1000000)
+      println()
+    }
+}