diff --git a/sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala b/sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala
index 9a10a23937fbb..b3fb097fb02cf 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala
@@ -550,6 +550,10 @@ private[sql] class SQLConf extends Serializable with CatalystConf {
     props.foreach { case (k, v) => setConfString(k, v) }
   }
 
+  def setConf(props: Map[String, String]): Unit = settings.synchronized {
+    props.foreach { case (k, v) => setConfString(k, v) }
+  }
+
   /** Set the given Spark SQL configuration property using a `string` value. */
   def setConfString(key: String, value: String): Unit = {
     require(key != null, "key cannot be null")
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/GeneratedAggregate.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/GeneratedAggregate.scala
index 8be63c677845a..9b4ddc3ac2d94 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/GeneratedAggregate.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/GeneratedAggregate.scala
@@ -270,8 +270,10 @@ case class GeneratedAggregate(
 
       val joinedRow = new JoinedRow3
 
-      if (groupingExpressions.isEmpty) {
-        // even with the empty input, value of empty buffer should be forwarded
+      if (!iter.hasNext && (partial || groupingExpressions.nonEmpty)) {
+        // even with empty input, final-global groupby should forward value of empty buffer
+        Iterator[InternalRow]()
+      } else if (groupingExpressions.isEmpty) {
         // TODO: Codegening anything other than the updateProjection is probably over kill.
         val buffer = newAggregationBuffer(EmptyRow).asInstanceOf[MutableRow]
         var currentRow: InternalRow = null
@@ -284,8 +286,6 @@ case class GeneratedAggregate(
 
         val resultProjection = resultProjectionBuilder()
         Iterator(resultProjection(buffer))
-      } else if (!iter.hasNext) {
-        Iterator[InternalRow]()
       } else if (unsafeEnabled && schemaSupportsUnsafe) {
         // unsafe aggregation buffer is not released if input is empty (see SPARK-8357)
         assert(iter.hasNext, "There should be at least one row for this path")
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/test/TestSQLContext.scala b/sql/core/src/main/scala/org/apache/spark/sql/test/TestSQLContext.scala
index 9fa394525d65c..1e8ec9ab81b60 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/test/TestSQLContext.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/test/TestSQLContext.scala
@@ -17,6 +17,7 @@
 
 package org.apache.spark.sql.test
 
+import scala.collection.immutable
 import scala.language.implicitConversions
 
 import org.apache.spark.{SparkConf, SparkContext}
@@ -36,9 +37,18 @@ class LocalSQLContext
   }
 
   protected[sql] class SQLSession extends super.SQLSession {
+    var backup: immutable.Map[String, String] = null
     protected[sql] override lazy val conf: SQLConf = new SQLConf {
       /** Fewer partitions to speed up testing. */
       override def numShufflePartitions: Int = this.getConf(SQLConf.SHUFFLE_PARTITIONS, 5)
+      backup = getAllConfs
+    }
+
+    protected[sql] def reset() = {
+      if (backup != null) {
+        conf.clear()
+        conf.setConf(backup)
+      }
     }
   }
 
@@ -50,6 +60,11 @@ class LocalSQLContext
     DataFrame(this, plan)
   }
 
+  /**
+   * Reset session conf to initial state
+   */
+  protected[sql] def resetConf(): Unit = currentSession().asInstanceOf[SQLSession].reset
+
 }
 
 object TestSQLContext extends LocalSQLContext
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/AggregateSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/AggregateSuite.scala
index 88620baddb520..fb088028f9a3b 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/AggregateSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/AggregateSuite.scala
@@ -17,7 +17,6 @@
 
 package org.apache.spark.sql.execution
 
-import org.apache.spark.SparkEnv
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.test.TestSQLContext
 import org.apache.spark.sql.types.DataTypes._
@@ -31,8 +30,8 @@ class AggregateSuite extends SparkPlanTest {
     val groupExpr = df.col("b").expr
     val aggrExpr = Alias(Count(Cast(groupExpr, LongType)), "Count")()
 
-    SparkEnv.get.conf.set("spark.unsafe.exceptionOnMemoryLeak", "true")
-    for (codegen <- Seq(false, true); partial <- Seq(false, true); unsafe <- Seq(false, true)) {
+    for ((codegen, unsafe) <- Seq((false, false), (true, false), (true, true));
+         partial <- Seq(false, true)) {
       TestSQLContext.conf.setConfString("spark.sql.codegen", String.valueOf(codegen))
       checkAnswer(
         df,
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala
index 13f3be8ca28d6..d454ca24dcd0a 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala
@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql.execution
 
+import org.scalatest.Tag
+
 import scala.language.implicitConversions
 import scala.reflect.runtime.universe.TypeTag
 import scala.util.control.NonFatal
@@ -43,6 +45,14 @@ class SparkPlanTest extends SparkFunSuite {
     TestSQLContext.implicits.localSeqToDataFrameHolder(data)
   }
 
+  protected override def test(testName: String, testTags: Tag*)(testFun: => Unit): Unit = {
+    try {
+      super.test(testName, testTags: _*)(testFun)
+    } finally {
+      TestSQLContext.resetConf()
+    }
+  }
+
   /**
    * Runs the plan and makes sure the answer matches the expected result.
    * @param input the input data to be used.