Adding unit test for straight to disk iterator methods.

core/src/test/scala/org/apache/spark/storage/LargeIteratorSuite.scala

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.storage
+
+import org.scalatest.FunSuite
+import org.apache.spark.{LocalSparkContext, SparkContext}
+
+class Expander(base:String, count:Int) extends Iterator[String] {
+  var i = 0;
+  def next() : String = {
+    i += 1;
+    return base + i.toString;
+  }
+  def hasNext() : Boolean = i < count;
+}
+
+object Expander {
+  def expand(s:String, i:Int) : Iterator[String] = {
+    return new Expander(s,i)
+  }
+}
+
+class LargeIteratorSuite extends FunSuite with LocalSparkContext {
+
+  val clusterUrl = "local-cluster[1,1,512]"
+  test("Flatmap iterator") {
+    sc = new SparkContext(clusterUrl, "mem_test");
+    val seeds = sc.parallelize( Array(
+      "This is the first sentence that we will test:",
+      "This is the second sentence that we will test:",
+      "This is the third sentence that we will test:"
+    ) );
+    val out = seeds.flatMap(Expander.expand(_,10000000));
+    out.map(_ + "...").persist(StorageLevel.DISK_ONLY).saveAsTextFile("./test.out")
+  }
+}