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diff --git a/core/src/test/scala/org/apache/spark/util/NextIteratorSuite.scala b/core/src/test/scala/org/apache/spark/util/NextIteratorSuite.scala
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+++ b/core/src/test/scala/org/apache/spark/util/NextIteratorSuite.scala
@@ -0,0 +1,85 @@
+/*
+ * 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.util
+
+import org.scalatest.FunSuite
+import org.scalatest.matchers.ShouldMatchers
+import scala.collection.mutable.Buffer
+import java.util.NoSuchElementException
+
+class NextIteratorSuite extends FunSuite with ShouldMatchers {
+  test("one iteration") {
+    val i = new StubIterator(Buffer(1))
+    i.hasNext should be === true
+    i.next should be === 1
+    i.hasNext should be === false
+    intercept[NoSuchElementException] { i.next() }
+  }
+  
+  test("two iterations") {
+    val i = new StubIterator(Buffer(1, 2))
+    i.hasNext should be === true
+    i.next should be === 1
+    i.hasNext should be === true
+    i.next should be === 2
+    i.hasNext should be === false
+    intercept[NoSuchElementException] { i.next() }
+  }
+
+  test("empty iteration") {
+    val i = new StubIterator(Buffer())
+    i.hasNext should be === false
+    intercept[NoSuchElementException] { i.next() }
+  }
+
+  test("close is called once for empty iterations") {
+    val i = new StubIterator(Buffer())
+    i.hasNext should be === false
+    i.hasNext should be === false
+    i.closeCalled should be === 1
+  }
+
+  test("close is called once for non-empty iterations") {
+    val i = new StubIterator(Buffer(1, 2))
+    i.next should be === 1
+    i.next should be === 2
+    // close isn't called until we check for the next element
+    i.closeCalled should be === 0
+    i.hasNext should be === false
+    i.closeCalled should be === 1
+    i.hasNext should be === false
+    i.closeCalled should be === 1
+  }
+
+  class StubIterator(ints: Buffer[Int])  extends NextIterator[Int] {
+    var closeCalled = 0
+    
+    override def getNext() = {
+      if (ints.size == 0) {
+        finished = true
+        0
+      } else {
+        ints.remove(0)
+      }
+    }
+
+    override def close() {
+      closeCalled += 1
+    }
+  }
+}