DummySmtpServer.java

/* vim: set ts=2 et sw=2 cindent fo=qroca: */

package com.globant.katari.tools;

import java.net.ServerSocket;
import java.util.Iterator;

import org.springframework.beans.DirectFieldAccessor;

import com.dumbster.smtp.SimpleSmtpServer;
import com.dumbster.smtp.SmtpMessage;

/** Dummy smtp server used for testing.
 *
 * This server is based on dumbster, but adds the possibility to start in an OS
 * selected port.
 */
public final class DummySmtpServer implements Iterable<SmtpMessage> {

  /** The created SimpleSmtpServer.
   *
   * This is never null.
   */
  private SimpleSmtpServer server;

  /** Private constructor.
   *
   * @param smtpServer The dumbster smtp server wrapped by this class. It is
   * never null.
   */
  private DummySmtpServer(final SimpleSmtpServer smtpServer) {
    server = smtpServer;
  }

  /** Creates a dummy smtp server and starts it.
   *
   * @param port the port number that the server will listen to.
   *
   * @return the created dummy server, never null.
   */
  public static DummySmtpServer start(final int port) {

    // This was copied from SimpleSmtpServer start operation, which has a race
    // condition: t.start calls notifyAll(), that is intended to wake this
    // thread that is waiting in server.
    //
    // The race happens because t.start may call notifyAll before this method
    // calls server.wait. We just moved t.start to the synchronized block. This
    // forces the new thread to wait until we this method calls server.wait().
    SimpleSmtpServer server = new SimpleSmtpServer(port);
    Thread t = new Thread(server);

    // Block until the server socket is created
    synchronized (server) {
      t.start();
      try {
        server.wait();
      } catch (InterruptedException e) {
        // Ignore don't care.
      }
    }
    return new DummySmtpServer(server);
  }

  /** Stops the server.
   *
   * Server is shutdown after processing of the current request is complete.
   */
  public synchronized void stop() {
    server.stop();
  }

  /** Obtains the port number where the server bound to.
   *
   * This operation is specially useful when the server is asked to start in
   * port 0, where the operating system selects the port number.
   *
   * @return an integer with the port number.
   */
  public synchronized int getPortNumber() {
    DirectFieldAccessor accesor = new DirectFieldAccessor(server);
    ServerSocket socket;
    socket = (ServerSocket) accesor.getPropertyValue("serverSocket");
    return socket.getLocalPort();
  }

  /** Get email received by this instance since start up.
   *
   * @return an iterator for all the received emails.
   */
  @SuppressWarnings("unchecked")
  public synchronized Iterator<SmtpMessage> iterator() {
    return (Iterator<SmtpMessage>) server.getReceivedEmail();
  }

  /** Gets the number of messages received.
   *
   * @return size of received email list.
   */
  public synchronized int getReceivedEmailSize() {
    return server.getReceivedEmailSize();
  }
}