001/*
002 * Copyright (C) 2008 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
005 * use this file except in compliance with the License.  You may obtain a copy
006 * of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
012 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
013 * License for the specific language governing permissions and limitations under
014 * the License.
015 */
016
017package com.google.common.util.concurrent.testing;
018
019import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
020
021import com.google.common.annotations.Beta;
022import com.google.common.annotations.GwtIncompatible;
023import com.google.common.util.concurrent.ListenableFuture;
024import java.util.concurrent.CountDownLatch;
025import java.util.concurrent.ExecutionException;
026import java.util.concurrent.TimeUnit;
027import junit.framework.Assert;
028
029/**
030 * A simple mock implementation of {@code Runnable} that can be used for testing ListenableFutures.
031 *
032 * @author Nishant Thakkar
033 * @since 10.0
034 */
035@Beta
036@GwtIncompatible
037public class MockFutureListener implements Runnable {
038  private final CountDownLatch countDownLatch;
039  private final ListenableFuture<?> future;
040
041  public MockFutureListener(ListenableFuture<?> future) {
042    this.countDownLatch = new CountDownLatch(1);
043    this.future = future;
044
045    future.addListener(this, directExecutor());
046  }
047
048  @Override
049  public void run() {
050    countDownLatch.countDown();
051  }
052
053  /**
054   * Verify that the listener completes in a reasonable amount of time, and Asserts that the future
055   * returns the expected data.
056   *
057   * @throws Throwable if the listener isn't called or if it resulted in a throwable or if the
058   *     result doesn't match the expected value.
059   */
060  public void assertSuccess(Object expectedData) throws Throwable {
061    // Verify that the listener executed in a reasonable amount of time.
062    Assert.assertTrue(countDownLatch.await(1L, TimeUnit.SECONDS));
063
064    try {
065      Assert.assertEquals(expectedData, future.get());
066    } catch (ExecutionException e) {
067      throw e.getCause();
068    }
069  }
070
071  /**
072   * Verify that the listener completes in a reasonable amount of time, and Asserts that the future
073   * throws an {@code ExecutableException} and that the cause of the {@code ExecutableException} is
074   * {@code expectedCause}.
075   */
076  public void assertException(Throwable expectedCause) throws Exception {
077    // Verify that the listener executed in a reasonable amount of time.
078    Assert.assertTrue(countDownLatch.await(1L, TimeUnit.SECONDS));
079
080    try {
081      future.get();
082      Assert.fail("This call was supposed to throw an ExecutionException");
083    } catch (ExecutionException expected) {
084      Assert.assertSame(expectedCause, expected.getCause());
085    }
086  }
087
088  public void assertTimeout() throws Exception {
089    // Verify that the listener does not get called in a reasonable amount of
090    // time.
091    Assert.assertFalse(countDownLatch.await(1L, TimeUnit.SECONDS));
092  }
093}