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      1 /*
      2  * Copyright (C) 2007 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.eventbus;
     18 
     19 import com.google.common.collect.Lists;
     20 
     21 import junit.framework.TestCase;
     22 
     23 import java.util.List;
     24 import java.util.concurrent.Executor;
     25 
     26 /**
     27  * Test case for {@link AsyncEventBus}.
     28  *
     29  * @author Cliff Biffle
     30  */
     31 public class AsyncEventBusTest extends TestCase {
     32   private static final String EVENT = "Hello";
     33 
     34   /** The executor we use to fake asynchronicity. */
     35   private FakeExecutor executor;
     36   private AsyncEventBus bus;
     37 
     38   @Override protected void setUp() throws Exception {
     39     super.setUp();
     40     executor = new FakeExecutor();
     41     bus = new AsyncEventBus(executor);
     42   }
     43 
     44   public void testBasicDistribution() {
     45     StringCatcher catcher = new StringCatcher();
     46     bus.register(catcher);
     47 
     48     // We post the event, but our Executor will not deliver it until instructed.
     49     bus.post(EVENT);
     50 
     51     List<String> events = catcher.getEvents();
     52     assertTrue("No events should be delivered synchronously.",
     53         events.isEmpty());
     54 
     55     // Now we find the task in our Executor and explicitly activate it.
     56     List<Runnable> tasks = executor.getTasks();
     57     assertEquals("One event dispatch task should be queued.", 1, tasks.size());
     58 
     59     tasks.get(0).run();
     60 
     61     assertEquals("One event should be delivered.", 1, events.size());
     62     assertEquals("Correct string should be delivered.", EVENT, events.get(0));
     63   }
     64 
     65   /**
     66    * An {@link Executor} wanna-be that simply records the tasks it's given.
     67    * Arguably the Worst Executor Ever.
     68    *
     69    * @author cbiffle
     70    *
     71    */
     72   public static class FakeExecutor implements Executor {
     73     List<Runnable> tasks = Lists.newArrayList();
     74 
     75     @Override
     76     public void execute(Runnable task) {
     77       tasks.add(task);
     78     }
     79 
     80     public List<Runnable> getTasks() {
     81       return tasks;
     82     }
     83   }
     84 
     85 }
     86