Java example source code file (AsyncEventBusTest.java)

This example Java source code file (AsyncEventBusTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

asynceventbus, asynceventbustest, correct, event, exception, fakeexecutor, hello, list, one, override, stringcatcher, testcase, threading, threads, util

The AsyncEventBusTest.java Java example source code

/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.eventbus;

import com.google.common.collect.Lists;

import junit.framework.TestCase;

import java.util.List;
import java.util.concurrent.Executor;

/**
 * Test case for {@link AsyncEventBus}.
 *
 * @author Cliff Biffle
 */
public class AsyncEventBusTest extends TestCase {
  private static final String EVENT = "Hello";

  /** The executor we use to fake asynchronicity. */
  private FakeExecutor executor;
  private AsyncEventBus bus;

  @Override protected void setUp() throws Exception {
    super.setUp();
    executor = new FakeExecutor();
    bus = new AsyncEventBus(executor);
  }

  public void testBasicDistribution() {
    StringCatcher catcher = new StringCatcher();
    bus.register(catcher);

    // We post the event, but our Executor will not deliver it until instructed.
    bus.post(EVENT);

    List<String> events = catcher.getEvents();
    assertTrue("No events should be delivered synchronously.",
        events.isEmpty());

    // Now we find the task in our Executor and explicitly activate it.
    List<Runnable> tasks = executor.getTasks();
    assertEquals("One event dispatch task should be queued.", 1, tasks.size());

    tasks.get(0).run();

    assertEquals("One event should be delivered.", 1, events.size());
    assertEquals("Correct string should be delivered.", EVENT, events.get(0));
  }

  /**
   * An {@link Executor} wanna-be that simply records the tasks it's given.
   * Arguably the Worst Executor Ever.
   *
   * @author cbiffle
   *
   */
  public static class FakeExecutor implements Executor {
    List<Runnable> tasks = Lists.newArrayList();

    @Override
    public void execute(Runnable task) {
      tasks.add(task);
    }

    public List<Runnable> getTasks() {
      return tasks;
    }
  }

}