Add test for mapWith()

Author: tedyu

core/src/test/scala/org/apache/spark/util/ClosureCleanerSuite.scala

@@ -93,6 +93,7 @@ class ClosureCleanerSuite extends FunSuite {
       expectCorrectException { TestUserClosuresActuallyCleaned.testMapPartitions(rdd) }
       expectCorrectException { TestUserClosuresActuallyCleaned.testMapPartitionsWithIndex(rdd) }
       expectCorrectException { TestUserClosuresActuallyCleaned.testFlatMapWith(rdd) }
+      expectCorrectException { TestUserClosuresActuallyCleaned.testMapWith(rdd) }
       expectCorrectException { TestUserClosuresActuallyCleaned.testZipPartitions2(rdd) }
       expectCorrectException { TestUserClosuresActuallyCleaned.testZipPartitions3(rdd) }
       expectCorrectException { TestUserClosuresActuallyCleaned.testZipPartitions4(rdd) }
@@ -269,7 +270,12 @@ private object TestUserClosuresActuallyCleaned {
         val random = prng.nextDouble()
         Seq(random * t, random * t * 10)}.
       count()
-    rdd.mapPartitionsWithIndex { (_, it) => return; it }.count()
+  }
+  def testMapWith(rdd: RDD[Int]): Unit = {
+    import java.util.Random
+    val randoms = rdd.mapWith(
+      (index: Int) => new Random(index + 42))
+      {(t: Int, prng: Random) => prng.nextDouble * t}.count()
   }
   def testZipPartitions2(rdd: RDD[Int]): Unit = {
     rdd.zipPartitions(rdd) { case (it1, it2) => return; it1 }.count()