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diff --git a/core/src/test/scala/org/apache/spark/util/ResetSystemProperties.scala b/core/src/test/scala/org/apache/spark/util/ResetSystemProperties.scala
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+++ b/core/src/test/scala/org/apache/spark/util/ResetSystemProperties.scala
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+/*
+ * 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.util
+
+import java.util.Properties
+
+import org.scalatest.{BeforeAndAfterEach, Suite}
+
+/**
+ * Mixin for automatically resetting system properties that are modified in ScalaTest tests.
+ * This resets the properties after each individual test.
+ *
+ * The order in which fixtures are mixed in affects the order in which they are invoked by tests.
+ * If we have a suite `MySuite extends FunSuite with Foo with Bar`, then
+ * Bar's `super` is Foo, so Bar's beforeEach() will and afterEach() methods will be invoked first
+ * by the rest runner.
+ *
+ * This means that ResetSystemProperties should appear as the last trait in test suites that it's
+ * mixed into in order to ensure that the system properties snapshot occurs as early as possible.
+ * ResetSystemProperties calls super.afterEach() before performing its own cleanup, ensuring that
+ * the old properties are restored as late as possible.
+ *
+ * See the "Composing fixtures by stacking traits" section at
+ * http://www.scalatest.org/user_guide/sharing_fixtures for more details about this pattern.
+ */
+private[spark] trait ResetSystemProperties extends BeforeAndAfterEach { this: Suite =>
+  var oldProperties: Properties = null
+
+  override def beforeEach(): Unit = {
+    oldProperties = new Properties(System.getProperties)
+    super.beforeEach()
+  }
+
+  override def afterEach(): Unit = {
+    try {
+      super.afterEach()
+    } finally {
+      System.setProperties(oldProperties)
+      oldProperties = null
+    }
+  }
+}