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.io.OutputStream;
  import java.io.PrintStream;
  import java.util.function.Consumer;
  import javax.annotation.concurrent.NotThreadSafe;
  
  /**
   * A rule for redirecting an output stream during a test suite. It sets
   * a print stream to the specified output stream during the lifetime
   * of this rule.
   */
  @NotThreadSafe
  public final class RedirectOutputRule extends AbstractResourceRule {
    private final OutputStream mOutputStream;
    private final Consumer<PrintStream> mRedirector;
    private PrintStream mInputStream;
    private PrintStream mNewOutput;
    private PrintStream mOldOutput;
  
    /**
     * @param inputStream the print stream to set as input
     * @param outputStream the output stream to set as output
     * @param redirector the stream redirection function (e.g. System::setOut)
     */
    public RedirectOutputRule(PrintStream inputStream, OutputStream outputStream,
                              Consumer<PrintStream> redirector) {
      mInputStream = inputStream;
      mOutputStream = outputStream;
      mRedirector = redirector;
    }
  
    @Override
    protected void before() throws Exception {
      mNewOutput = new PrintStream(mOutputStream);
      mOldOutput = mInputStream;
      mRedirector.accept(mNewOutput);
    }
  
    @Override
    protected void after() {
      mRedirector.accept(mOldOutput);
    }
  }
  