address comments

core/src/test/scala/org/apache/spark/SerializerHelper.scala

@@ -0,0 +1,44 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark
+
+import java.io.{ByteArrayInputStream, ByteArrayOutputStream, ObjectInputStream, ObjectOutputStream}
+
+trait SerializerHelper {
+
+  protected def roundtripSerialize[T](obj: T): T = {
+    deserializeFromBytes(serializeToBytes(obj))
+  }
+
+  protected def serializeToBytes[T](o: T): Array[Byte] = {
+    val baos = new ByteArrayOutputStream
+    val oos = new ObjectOutputStream(baos)
+    try {
+      oos.writeObject(o)
+      baos.toByteArray
+    } finally {
+      oos.close()
+    }
+  }
+
+  protected def deserializeFromBytes[T](bytes: Array[Byte]): T = {
+    val bais = new ByteArrayInputStream(bytes)
+    val ois = new ObjectInputStream(bais)
+    ois.readObject().asInstanceOf[T]
+  }
+}

core/src/test/scala/org/apache/spark/SparkFunSuite.scala

@@ -17,7 +17,7 @@
 
 package org.apache.spark
 
-import java.io.{ByteArrayInputStream, ByteArrayOutputStream, File, ObjectInputStream, ObjectOutputStream}
+import java.io.File
 import java.nio.charset.StandardCharsets.UTF_8
 import java.nio.file.{Files, Path}
 import java.util.{Locale, TimeZone}
@@ -463,27 +463,6 @@ abstract class SparkFunSuite
       condition = "TABLE_OR_VIEW_ALREADY_EXISTS",
       parameters = Map("relationName" -> tableName))
 
-  protected def roundtripSerialize[T](obj: T): T = {
-    deserializeFromBytes(serializeToBytes(obj))
-  }
-
-  protected def serializeToBytes[T](o: T): Array[Byte] = {
-    val baos = new ByteArrayOutputStream
-    val oos = new ObjectOutputStream(baos)
-    try {
-      oos.writeObject(o)
-      baos.toByteArray
-    } finally {
-      oos.close()
-    }
-  }
-
-  protected def deserializeFromBytes[T](bytes: Array[Byte]): T = {
-    val bais = new ByteArrayInputStream(bytes)
-    val ois = new ObjectInputStream(bais)
-    ois.readObject().asInstanceOf[T]
-  }
-
   case class ExpectedContext(
       contextType: QueryContextType,
       objectType: String,

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

@@ -18,9 +18,9 @@ package org.apache.spark.util
 
 import java.io.NotSerializableException
 
-import org.apache.spark.SparkFunSuite
+import org.apache.spark.{SerializerHelper, SparkFunSuite}
 
-class BestEffortLazyValSuite extends SparkFunSuite {
+class BestEffortLazyValSuite extends SparkFunSuite with SerializerHelper {
 
   test("BestEffortLazy works") {
     var test: Option[Object] = None

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

@@ -16,9 +16,9 @@
  */
 package org.apache.spark.util
 
-import org.apache.spark.SparkFunSuite
+import org.apache.spark.{SerializerHelper, SparkFunSuite}
 
-class TransientBestEffortLazyValSuite extends SparkFunSuite {
+class TransientBestEffortLazyValSuite extends SparkFunSuite with SerializerHelper {
 
   test("TransientBestEffortLazyVal works") {
     var test: Option[Object] = None