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      1 /*
      2  * Copyright (C) 2009 The Guava Authors
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.common.util.concurrent;
     18 
     19 import static com.google.common.base.Preconditions.checkNotNull;
     20 import static junit.framework.Assert.assertEquals;
     21 import static junit.framework.Assert.assertFalse;
     22 import static junit.framework.Assert.assertTrue;
     23 import static junit.framework.Assert.fail;
     24 
     25 import java.util.concurrent.CancellationException;
     26 import java.util.concurrent.CountDownLatch;
     27 import java.util.concurrent.ExecutionException;
     28 import java.util.concurrent.ExecutorService;
     29 import java.util.concurrent.Executors;
     30 import java.util.concurrent.TimeUnit;
     31 
     32 import javax.annotation.Nullable;
     33 
     34 /**
     35  * Used to test listenable future implementations.
     36  *
     37  * @author Sven Mawson
     38  */
     39 public class ListenableFutureTester {
     40 
     41   private final ExecutorService exec;
     42   private final ListenableFuture<?> future;
     43   private final CountDownLatch latch;
     44 
     45   public ListenableFutureTester(ListenableFuture<?> future) {
     46     this.exec = Executors.newCachedThreadPool();
     47     this.future = checkNotNull(future);
     48     this.latch = new CountDownLatch(1);
     49   }
     50 
     51   public void setUp() {
     52     future.addListener(new Runnable() {
     53       @Override public void run() {
     54         latch.countDown();
     55       }
     56     }, exec);
     57 
     58     assertEquals(1, latch.getCount());
     59     assertFalse(future.isDone());
     60     assertFalse(future.isCancelled());
     61   }
     62 
     63   public void tearDown() {
     64     exec.shutdown();
     65   }
     66 
     67   public void testCompletedFuture(@Nullable Object expectedValue)
     68       throws InterruptedException, ExecutionException {
     69     assertTrue(future.isDone());
     70     assertFalse(future.isCancelled());
     71 
     72     assertTrue(latch.await(5, TimeUnit.SECONDS));
     73     assertTrue(future.isDone());
     74     assertFalse(future.isCancelled());
     75 
     76     assertEquals(expectedValue, future.get());
     77   }
     78 
     79   public void testCancelledFuture()
     80       throws InterruptedException, ExecutionException {
     81     assertTrue(future.isDone());
     82     assertTrue(future.isCancelled());
     83 
     84     assertTrue(latch.await(5, TimeUnit.SECONDS));
     85     assertTrue(future.isDone());
     86     assertTrue(future.isCancelled());
     87 
     88     try {
     89       future.get();
     90       fail("Future should throw CancellationException on cancel.");
     91     } catch (CancellationException expected) {}
     92   }
     93 
     94   public void testFailedFuture(@Nullable String message)
     95       throws InterruptedException {
     96     assertTrue(future.isDone());
     97     assertFalse(future.isCancelled());
     98 
     99     assertTrue(latch.await(5, TimeUnit.SECONDS));
    100     assertTrue(future.isDone());
    101     assertFalse(future.isCancelled());
    102 
    103     try {
    104       future.get();
    105       fail("Future should rethrow the exception.");
    106     } catch (ExecutionException e) {
    107       assertEquals(message, e.getCause().getMessage());
    108     }
    109   }
    110 }
    111