content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio;
  
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * A rule for setting a system property to a value and then restoring the property to its old value.
   */
  public final class SystemPropertyRule extends AbstractResourceRule {
    private final Map<String, String> mProperties;
    private final Map<String, String> mOriginalProperties = new HashMap<>();
    private final Set<String> mOriginalNullProperties = new HashSet<>();
  
    /**
     * @param keyValuePairs map from system property keys to the values to set them to
     */
    public SystemPropertyRule(Map<String, String> keyValuePairs) {
      mProperties = keyValuePairs;
    }
  
    /**
     * @param propertyName the name of the property to set
     * @param value the value to set it to, if null un-setting the propertyName
     */
    public SystemPropertyRule(String propertyName, String value) {
      mProperties = new HashMap<>();
      mProperties.put(propertyName, value);
    }
  
    @Override
    public void before() {
      for (Map.Entry<String, String> entry : mProperties.entrySet()) {
        String key = entry.getKey();
        String value = entry.getValue();
        String prevValue = System.getProperty(key);
        if (prevValue == null) {
          mOriginalNullProperties.add(key);
        } else {
          mOriginalProperties.put(key, prevValue);
        }
        if (value == null) {
          System.clearProperty(key);
        } else {
          System.setProperty(key, value);
        }
      }
    }
  
    @Override
    public void after() {
      for (Map.Entry<String, String> entry : mOriginalProperties.entrySet()) {
        System.setProperty(entry.getKey(), entry.getValue());
      }
      for (String key : mOriginalNullProperties) {
        System.clearProperty(key);
      }
    }
  }
  