content: /*
   * 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.beam.sdk.testing;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import org.junit.rules.ExternalResource;
  import org.junit.rules.TestRule;
  
  /** Saves and restores the current system properties for tests. */
  public class RestoreSystemProperties extends ExternalResource implements TestRule {
    private byte[] originalProperties;
  
    @Override
    protected void before() throws Throwable {
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      System.getProperties().store(baos, "");
      baos.close();
      originalProperties = baos.toByteArray();
    }
  
    @Override
    protected void after() {
      try (ByteArrayInputStream bais = new ByteArrayInputStream(originalProperties)) {
        System.getProperties().clear();
        System.getProperties().load(bais);
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }
  