Beefed up unit test.

Author: rxin

core/src/main/scala/org/apache/spark/util/JsonProtocol.scala

@@ -471,7 +471,6 @@ private[spark] object JsonProtocol {
 
   def stageInfoFromJson(json: JValue): StageInfo = {
     val stageId = (json \ "Stage ID").extract[Int]
-    val stageAttempt = (json \ "Attempt").extractOpt[Int].getOrElse(1)
     val stageName = (json \ "Stage Name").extract[String]
     val numTasks = (json \ "Number of Tasks").extract[Int]
     val rddInfos = (json \ "RDD Info").extract[List[JValue]].map(rddInfoFromJson)

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

@@ -270,10 +270,12 @@ class JsonProtocolSuite extends FunSuite {
   private def assertEquals(info1: TaskInfo, info2: TaskInfo) {
     assert(info1.taskId === info2.taskId)
     assert(info1.index === info2.index)
+    assert(info1.attempt === info2.attempt)
     assert(info1.launchTime === info2.launchTime)
     assert(info1.executorId === info2.executorId)
     assert(info1.host === info2.host)
     assert(info1.taskLocality === info2.taskLocality)
+    assert(info1.speculative === info2.speculative)
     assert(info1.gettingResultTime === info2.gettingResultTime)
     assert(info1.finishTime === info2.finishTime)
     assert(info1.failed === info2.failed)