add a small wait to one task to make sure some task runtime really is non-zero

core/src/test/scala/spark/scheduler/SparkListenerSuite.scala

@@ -17,16 +17,22 @@ class SparkListenerSuite extends FunSuite with LocalSparkContext with ShouldMatc
     val listener = new SaveStageInfo
     sc.addSparkListener(listener)
     sc.addSparkListener(new StatsReportListener)
+    //just to make sure some of the tasks take a noticeable amount of time
+    val w = {i:Int =>
+      if (i == 0)
+        Thread.sleep(25)
+      i
+    }
 
-    val d = sc.parallelize(1 to 1e4.toInt, 64)
+    val d = sc.parallelize(1 to 1e4.toInt, 64).map{i => w(i)}
     d.count
     listener.stageInfos.size should be (1)
 
-    val d2 = d.map{i => i -> i * 2}.setName("shuffle input 1")
+    val d2 = d.map{i => w(i) -> i * 2}.setName("shuffle input 1")
 
-    val d3 = d.map{i => i -> (0 to (i % 5))}.setName("shuffle input 2")
+    val d3 = d.map{i => w(i) -> (0 to (i % 5))}.setName("shuffle input 2")
 
-    val d4 = d2.cogroup(d3, 64).map{case(k,(v1,v2)) => k -> (v1.size, v2.size)}
+    val d4 = d2.cogroup(d3, 64).map{case(k,(v1,v2)) => w(k) -> (v1.size, v2.size)}
     d4.setName("A Cogroup")
 
     d4.collectAsMap