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 com.google.common.base.Throwables;
  import org.junit.rules.ExternalResource;
  
  import java.io.Closeable;
  import javax.annotation.concurrent.NotThreadSafe;
  
  /**
   * A rule for test rule to set and restore an external resource for each test case.
   */
  @NotThreadSafe
  public abstract class AbstractResourceRule extends ExternalResource {
  
    /**
     * @return a Closeable resource that makes the modification of the resource on construction and
     *         restore the rule to the previous value on close.
     */
    public Closeable toResource() {
      return new Closeable() {
        {
          try {
            before();
          } catch (Throwable t) {
            Throwables.propagateIfPossible(t);
            throw new RuntimeException(t);
          }
        }
  
        @Override
        public void close() {
          after();
        }
      };
    }
  }
  