tests: Fix race condition in ComputeSchedulerSuite

core/src/test/scala/org/apache/spark/monotasks/compute/ComputeSchedulerSuite.scala

@@ -18,9 +18,14 @@ package org.apache.spark.monotasks.compute
 
 import java.nio.ByteBuffer
 
+import scala.concurrent.duration._
+import scala.language.postfixOps
+
 import org.mockito.Mockito.{mock, never, timeout, verify, when}
 
 import org.scalatest.FunSuite
+import org.scalatest.concurrent.Eventually.{eventually, interval => scalatestInterval,
+  timeout => scalatestTimeout}
 
 import org.apache.spark.TaskContextImpl
 import org.apache.spark.storage.{BlockManager, MemoryStore, TestBlockId}
@@ -96,8 +101,11 @@ class ComputeSchedulerSuite extends FunSuite {
     computeScheduler.submitTask(computeMonotask2)
     computeScheduler.submitTask(computeMonotask3)
 
-    assert(computeMonotask1.isStarted)
-    assert(computeMonotask2.isStarted)
+    // Wrap this in an eventually loop, since the compute threads pull tasks asynchronously.
+    eventually(scalatestTimeout(3 seconds), scalatestInterval(10 milliseconds)) {
+      assert(computeMonotask1.isStarted)
+      assert(computeMonotask2.isStarted)
+    }
     assert(!computeMonotask3.isStarted)
 
     // Now submit a prepare monotask, and finish one of the other compute monotasks. The prepare