Cleanup SPARK_YARN_MODE in tests.

Author: Marcelo Vanzin

resource-managers/yarn/src/test/scala/org/apache/spark/deploy/yarn/BaseYarnClusterSuite.scala

@@ -62,18 +62,14 @@ abstract class BaseYarnClusterSuite
   protected var hadoopConfDir: File = _
   private var logConfDir: File = _
 
-  var oldSystemProperties: Properties = null
-
   def newYarnConfig(): YarnConfiguration
 
   override def beforeAll() {
     super.beforeAll()
-    oldSystemProperties = SerializationUtils.clone(System.getProperties)
 
     tempDir = Utils.createTempDir()
     logConfDir = new File(tempDir, "log4j")
     logConfDir.mkdir()
-    System.setProperty("SPARK_YARN_MODE", "true")
 
     val logConfFile = new File(logConfDir, "log4j.properties")
     Files.write(LOG4J_CONF, logConfFile, StandardCharsets.UTF_8)
@@ -124,7 +120,6 @@ abstract class BaseYarnClusterSuite
     try {
       yarnCluster.stop()
     } finally {
-      System.setProperties(oldSystemProperties)
       super.afterAll()
     }
   }

resource-managers/yarn/src/test/scala/org/apache/spark/deploy/yarn/ClientSuite.scala

@@ -24,7 +24,6 @@ import java.util.Properties
 import scala.collection.JavaConverters._
 import scala.collection.mutable.{HashMap => MutableHashMap}
 
-import org.apache.commons.lang3.SerializationUtils
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.fs.Path
 import org.apache.hadoop.mapreduce.MRJobConfig
@@ -36,34 +35,18 @@ import org.apache.hadoop.yarn.conf.YarnConfiguration
 import org.apache.hadoop.yarn.util.Records
 import org.mockito.Matchers.{eq => meq, _}
 import org.mockito.Mockito._
-import org.scalatest.{BeforeAndAfterAll, Matchers}
+import org.scalatest.Matchers
 
 import org.apache.spark.{SparkConf, SparkFunSuite, TestUtils}
 import org.apache.spark.deploy.yarn.config._
-import org.apache.spark.util.{ResetSystemProperties, SparkConfWithEnv, Utils}
+import org.apache.spark.util.{SparkConfWithEnv, Utils}
 
-class ClientSuite extends SparkFunSuite with Matchers with BeforeAndAfterAll
-  with ResetSystemProperties {
+class ClientSuite extends SparkFunSuite with Matchers {
 
   import Client._
 
   var oldSystemProperties: Properties = null
 
-  override def beforeAll(): Unit = {
-    super.beforeAll()
-    oldSystemProperties = SerializationUtils.clone(System.getProperties)
-    System.setProperty("SPARK_YARN_MODE", "true")
-  }
-
-  override def afterAll(): Unit = {
-    try {
-      System.setProperties(oldSystemProperties)
-      oldSystemProperties = null
-    } finally {
-      super.afterAll()
-    }
-  }
-
   test("default Yarn application classpath") {
     getDefaultYarnApplicationClasspath should be(Fixtures.knownDefYarnAppCP)
   }

resource-managers/yarn/src/test/scala/org/apache/spark/deploy/yarn/security/YARNHadoopDelegationTokenManagerSuite.scala

@@ -31,19 +31,10 @@ class YARNHadoopDelegationTokenManagerSuite extends SparkFunSuite with Matchers
 
   override def beforeAll(): Unit = {
     super.beforeAll()
-
-    System.setProperty("SPARK_YARN_MODE", "true")
-
     sparkConf = new SparkConf()
     hadoopConf = new Configuration()
   }
 
-  override def afterAll(): Unit = {
-    super.afterAll()
-
-    System.clearProperty("SPARK_YARN_MODE")
-  }
-
   test("Correctly loads credential providers") {
     credentialManager = new YARNHadoopDelegationTokenManager(
       sparkConf,