fix tests

Author: squito

core/src/test/scala/org/apache/spark/executor/ExecutorSuite.scala

@@ -42,7 +42,7 @@ import org.apache.spark.metrics.MetricsSystem
 import org.apache.spark.rdd.RDD
 import org.apache.spark.rpc.RpcEnv
 import org.apache.spark.scheduler.{FakeTask, ResultTask, TaskDescription}
-import org.apache.spark.serializer.JavaSerializer
+import org.apache.spark.serializer.{JavaSerializer, SerializerManager}
 import org.apache.spark.shuffle.FetchFailedException
 import org.apache.spark.storage.BlockManagerId
 import org.apache.spark.util.UninterruptibleThread
@@ -234,6 +234,7 @@ class ExecutorSuite extends SparkFunSuite with LocalSparkContext with MockitoSug
     val mockMemoryManager = mock[MemoryManager]
     when(mockEnv.conf).thenReturn(conf)
     when(mockEnv.serializer).thenReturn(serializer)
+    when(mockEnv.serializerManager).thenReturn(mock[SerializerManager])
     when(mockEnv.rpcEnv).thenReturn(mockRpcEnv)
     when(mockEnv.metricsSystem).thenReturn(mockMetricsSystem)
     when(mockEnv.memoryManager).thenReturn(mockMemoryManager)