Added sorting testing suite

core/src/test/scala/spark/SortingSuite.scala

+package spark
+
+import scala.collection.mutable.HashMap
+import org.scalatest.FunSuite
+import SparkContext._
+
+class SortingSuite extends FunSuite {
+  test("sortByKey") {
+      val sc = new SparkContext("local", "test")
+      val pairs = sc.parallelize(Array((1, 0), (2, 0), (0, 0), (3, 0)))
+      assert(pairs.sortByKey().collect() === Array((0,0), (1,0), (2,0), (3,0)))
+      sc.stop()
+  }
+
+  test("sortLargeArray") {
+      val sc = new SparkContext("local", "test")
+      val rand = new scala.util.Random()
+      val pairArr = Array.fill(1000) { (rand.nextInt(), rand.nextInt()) }
+      val pairs = sc.parallelize(pairArr)
+      assert(pairs.sortByKey().collect() === pairArr.sortBy(_._1))
+      sc.stop()
+  }
+
+  test("sortDescending") {
+      val sc = new SparkContext("local", "test")
+      val rand = new scala.util.Random()
+      val pairArr = Array.fill(1000) { (rand.nextInt(), rand.nextInt()) }
+      val pairs = sc.parallelize(pairArr)
+      assert(pairs.sortByKey(false).collect() === pairArr.sortWith((x, y) => x._1 > y._1))
+      sc.stop()
+  }
+
+  test("sortHighParallelism") {
+      val sc = new SparkContext("local", "test")
+      val rand = new scala.util.Random()
+      val pairArr = Array.fill(3000) { (rand.nextInt(), rand.nextInt()) }
+      val pairs = sc.parallelize(pairArr, 300)
+      assert(pairs.sortByKey().collect() === pairArr.sortBy(_._1))
+      sc.stop()
+  }
+}
+