Java example source code file (AbstractServiceTest.java)

This example Java source code file (AbstractServiceTest.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

abstractservice, countdownlatch, exception, illegalstateexception, manualswitchedservice, noopservice, noopthreadedservice, override, recordinglistener, runtimeexception, startfailingservice, stopfailingservice, threadedservice, threading, threads, throwable, util

The AbstractServiceTest.java Java example source code

/*
 * Copyright (C) 2009 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.util.concurrent;

import static com.google.common.truth.Truth.assertThat;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static java.lang.Thread.currentThread;
import static java.util.concurrent.TimeUnit.SECONDS;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.Service.Listener;
import com.google.common.util.concurrent.Service.State;

import junit.framework.TestCase;

import java.lang.Thread.UncaughtExceptionHandler;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

import javax.annotation.concurrent.GuardedBy;

/**
 * Unit test for {@link AbstractService}.
 *
 * @author Jesse Wilson
 */
public class AbstractServiceTest extends TestCase {

  private static final long LONG_TIMEOUT_MILLIS = 2500;
  private Thread executionThread;
  private Throwable thrownByExecutionThread;

  public void testNoOpServiceStartStop() throws Exception {
    NoOpService service = new NoOpService();
    RecordingListener listener = RecordingListener.record(service);

    assertEquals(State.NEW, service.state());
    assertFalse(service.isRunning());
    assertFalse(service.running);

    service.startAsync();
    assertEquals(State.RUNNING, service.state());
    assertTrue(service.isRunning());
    assertTrue(service.running);

    service.stopAsync();
    assertEquals(State.TERMINATED, service.state());
    assertFalse(service.isRunning());
    assertFalse(service.running);
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.STOPPING,
            State.TERMINATED),
        listener.getStateHistory());
  }

  public void testNoOpServiceStartAndWaitStopAndWait() throws Exception {
    NoOpService service = new NoOpService();

    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());

    service.stopAsync().awaitTerminated();
    assertEquals(State.TERMINATED, service.state());
  }

  public void testNoOpServiceStartAsyncAndAwaitStopAsyncAndAwait() throws Exception {
    NoOpService service = new NoOpService();

    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());

    service.stopAsync().awaitTerminated();
    assertEquals(State.TERMINATED, service.state());
  }

  public void testNoOpServiceStopIdempotence() throws Exception {
    NoOpService service = new NoOpService();
    RecordingListener listener = RecordingListener.record(service);
    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());

    service.stopAsync();
    service.stopAsync();
    assertEquals(State.TERMINATED, service.state());
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.STOPPING,
            State.TERMINATED),
        listener.getStateHistory());
  }

  public void testNoOpServiceStopIdempotenceAfterWait() throws Exception {
    NoOpService service = new NoOpService();

    service.startAsync().awaitRunning();

    service.stopAsync().awaitTerminated();
    service.stopAsync();
    assertEquals(State.TERMINATED, service.state());
  }

  public void testNoOpServiceStopIdempotenceDoubleWait() throws Exception {
    NoOpService service = new NoOpService();

    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());

    service.stopAsync().awaitTerminated();
    service.stopAsync().awaitTerminated();
    assertEquals(State.TERMINATED, service.state());
  }

  public void testNoOpServiceStartStopAndWaitUninterruptible()
      throws Exception {
    NoOpService service = new NoOpService();

    currentThread().interrupt();
    try {
      service.startAsync().awaitRunning();
      assertEquals(State.RUNNING, service.state());

      service.stopAsync().awaitTerminated();
      assertEquals(State.TERMINATED, service.state());

      assertTrue(currentThread().isInterrupted());
    } finally {
      Thread.interrupted(); // clear interrupt for future tests
    }
  }

  private static class NoOpService extends AbstractService {
    boolean running = false;

    @Override protected void doStart() {
      assertFalse(running);
      running = true;
      notifyStarted();
    }

    @Override protected void doStop() {
      assertTrue(running);
      running = false;
      notifyStopped();
    }
  }

  public void testManualServiceStartStop() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();
    RecordingListener listener = RecordingListener.record(service);

    service.startAsync();
    assertEquals(State.STARTING, service.state());
    assertFalse(service.isRunning());
    assertTrue(service.doStartCalled);

    service.notifyStarted(); // usually this would be invoked by another thread
    assertEquals(State.RUNNING, service.state());
    assertTrue(service.isRunning());

    service.stopAsync();
    assertEquals(State.STOPPING, service.state());
    assertFalse(service.isRunning());
    assertTrue(service.doStopCalled);

    service.notifyStopped(); // usually this would be invoked by another thread
    assertEquals(State.TERMINATED, service.state());
    assertFalse(service.isRunning());
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.STOPPING,
            State.TERMINATED),
            listener.getStateHistory());

  }

  public void testManualServiceNotifyStoppedWhileRunning() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();
    RecordingListener listener = RecordingListener.record(service);

    service.startAsync();
    service.notifyStarted();
    service.notifyStopped();
    assertEquals(State.TERMINATED, service.state());
    assertFalse(service.isRunning());
    assertFalse(service.doStopCalled);

    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.TERMINATED),
            listener.getStateHistory());
  }

  public void testManualServiceStopWhileStarting() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();
    RecordingListener listener = RecordingListener.record(service);

    service.startAsync();
    assertEquals(State.STARTING, service.state());
    assertFalse(service.isRunning());
    assertTrue(service.doStartCalled);

    service.stopAsync();
    assertEquals(State.STOPPING, service.state());
    assertFalse(service.isRunning());
    assertFalse(service.doStopCalled);

    service.notifyStarted();
    assertEquals(State.STOPPING, service.state());
    assertFalse(service.isRunning());
    assertTrue(service.doStopCalled);

    service.notifyStopped();
    assertEquals(State.TERMINATED, service.state());
    assertFalse(service.isRunning());
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.STOPPING,
            State.TERMINATED),
            listener.getStateHistory());
  }

  /**
   * This tests for a bug where if {@link Service#stopAsync()} was called while the service was
   * {@link State#STARTING} more than once, the {@link Listener#stopping(State)} callback would get
   * called multiple times.
   */
  public void testManualServiceStopMultipleTimesWhileStarting() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();
    final AtomicInteger stopppingCount = new AtomicInteger();
    service.addListener(new Listener() {
      @Override public void stopping(State from) {
        stopppingCount.incrementAndGet();
      }
    }, directExecutor());

    service.startAsync();
    service.stopAsync();
    assertEquals(1, stopppingCount.get());
    service.stopAsync();
    assertEquals(1, stopppingCount.get());
  }

  public void testManualServiceStopWhileNew() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();
    RecordingListener listener = RecordingListener.record(service);

    service.stopAsync();
    assertEquals(State.TERMINATED, service.state());
    assertFalse(service.isRunning());
    assertFalse(service.doStartCalled);
    assertFalse(service.doStopCalled);
    assertEquals(ImmutableList.of(State.TERMINATED), listener.getStateHistory());
  }

  public void testManualServiceFailWhileStarting() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();
    RecordingListener listener = RecordingListener.record(service);
    service.startAsync();
    service.notifyFailed(EXCEPTION);
    assertEquals(ImmutableList.of(State.STARTING, State.FAILED), listener.getStateHistory());
  }

  public void testManualServiceFailWhileRunning() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();
    RecordingListener listener = RecordingListener.record(service);
    service.startAsync();
    service.notifyStarted();
    service.notifyFailed(EXCEPTION);
    assertEquals(ImmutableList.of(State.STARTING, State.RUNNING, State.FAILED),
        listener.getStateHistory());
  }

  public void testManualServiceFailWhileStopping() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();
    RecordingListener listener = RecordingListener.record(service);
    service.startAsync();
    service.notifyStarted();
    service.stopAsync();
    service.notifyFailed(EXCEPTION);
    assertEquals(ImmutableList.of(State.STARTING, State.RUNNING, State.STOPPING, State.FAILED),
        listener.getStateHistory());
  }

  public void testManualServiceUnrequestedStop() {
    ManualSwitchedService service = new ManualSwitchedService();

    service.startAsync();

    service.notifyStarted();
    assertEquals(State.RUNNING, service.state());
    assertTrue(service.isRunning());
    assertFalse(service.doStopCalled);

    service.notifyStopped();
    assertEquals(State.TERMINATED, service.state());
    assertFalse(service.isRunning());
    assertFalse(service.doStopCalled);
  }

  /**
   * The user of this service should call {@link #notifyStarted} and {@link
   * #notifyStopped} after calling {@link #startAsync} and {@link #stopAsync}.
   */
  private static class ManualSwitchedService extends AbstractService {
    boolean doStartCalled = false;
    boolean doStopCalled = false;

    @Override protected void doStart() {
      assertFalse(doStartCalled);
      doStartCalled = true;
    }

    @Override protected void doStop() {
      assertFalse(doStopCalled);
      doStopCalled = true;
    }
  }

  public void testAwaitTerminated() throws Exception {
    final NoOpService service = new NoOpService();
    Thread waiter = new Thread() {
      @Override public void run() {
        service.awaitTerminated();
      }
    };
    waiter.start();
    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());
    service.stopAsync();
    waiter.join(LONG_TIMEOUT_MILLIS);  // ensure that the await in the other thread is triggered
    assertFalse(waiter.isAlive());
  }

  public void testAwaitTerminated_FailedService() throws Exception {
    final ManualSwitchedService service = new ManualSwitchedService();
    final AtomicReference<Throwable> exception = Atomics.newReference();
    Thread waiter = new Thread() {
      @Override public void run() {
        try {
          service.awaitTerminated();
          fail("Expected an IllegalStateException");
        } catch (Throwable t) {
          exception.set(t);
        }
      }
    };
    waiter.start();
    service.startAsync();
    service.notifyStarted();
    assertEquals(State.RUNNING, service.state());
    service.notifyFailed(EXCEPTION);
    assertEquals(State.FAILED, service.state());
    waiter.join(LONG_TIMEOUT_MILLIS);
    assertFalse(waiter.isAlive());
    assertThat(exception.get()).isInstanceOf(IllegalStateException.class);
    assertEquals(EXCEPTION, exception.get().getCause());
  }

  public void testThreadedServiceStartAndWaitStopAndWait() throws Throwable {
    ThreadedService service = new ThreadedService();
    RecordingListener listener = RecordingListener.record(service);
    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());

    service.awaitRunChecks();

    service.stopAsync().awaitTerminated();
    assertEquals(State.TERMINATED, service.state());

    throwIfSet(thrownByExecutionThread);
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.STOPPING,
            State.TERMINATED),
            listener.getStateHistory());
  }

  public void testThreadedServiceStopIdempotence() throws Throwable {
    ThreadedService service = new ThreadedService();

    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());

    service.awaitRunChecks();

    service.stopAsync();
    service.stopAsync().awaitTerminated();
    assertEquals(State.TERMINATED, service.state());

    throwIfSet(thrownByExecutionThread);
  }

  public void testThreadedServiceStopIdempotenceAfterWait()
      throws Throwable {
    ThreadedService service = new ThreadedService();

    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());

    service.awaitRunChecks();

    service.stopAsync().awaitTerminated();
    service.stopAsync();
    assertEquals(State.TERMINATED, service.state());

    executionThread.join();

    throwIfSet(thrownByExecutionThread);
  }

  public void testThreadedServiceStopIdempotenceDoubleWait()
      throws Throwable {
    ThreadedService service = new ThreadedService();

    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());

    service.awaitRunChecks();

    service.stopAsync().awaitTerminated();
    service.stopAsync().awaitTerminated();
    assertEquals(State.TERMINATED, service.state());

    throwIfSet(thrownByExecutionThread);
  }

  public void testManualServiceFailureIdempotence() {
    ManualSwitchedService service = new ManualSwitchedService();
    /*
     * Set up a RecordingListener to perform its built-in assertions, even though we won't look at
     * its state history.
     */
    RecordingListener unused = RecordingListener.record(service);
    service.startAsync();
    service.notifyFailed(new Exception("1"));
    service.notifyFailed(new Exception("2"));
    assertThat(service.failureCause()).hasMessage("1");
    try {
      service.awaitRunning();
      fail();
    } catch (IllegalStateException e) {
      assertThat(e.getCause()).hasMessage("1");
    }
  }

  private class ThreadedService extends AbstractService {
    final CountDownLatch hasConfirmedIsRunning = new CountDownLatch(1);

    /*
     * The main test thread tries to stop() the service shortly after
     * confirming that it is running. Meanwhile, the service itself is trying
     * to confirm that it is running. If the main thread's stop() call happens
     * before it has the chance, the test will fail. To avoid this, the main
     * thread calls this method, which waits until the service has performed
     * its own "running" check.
     */
    void awaitRunChecks() throws InterruptedException {
      assertTrue("Service thread hasn't finished its checks. "
          + "Exception status (possibly stale): " + thrownByExecutionThread,
          hasConfirmedIsRunning.await(10, SECONDS));
    }

    @Override protected void doStart() {
      assertEquals(State.STARTING, state());
      invokeOnExecutionThreadForTest(new Runnable() {
        @Override public void run() {
          assertEquals(State.STARTING, state());
          notifyStarted();
          assertEquals(State.RUNNING, state());
          hasConfirmedIsRunning.countDown();
        }
      });
    }

    @Override protected void doStop() {
      assertEquals(State.STOPPING, state());
      invokeOnExecutionThreadForTest(new Runnable() {
        @Override public void run() {
          assertEquals(State.STOPPING, state());
          notifyStopped();
          assertEquals(State.TERMINATED, state());
        }
      });
    }
  }

  private void invokeOnExecutionThreadForTest(Runnable runnable) {
    executionThread = new Thread(runnable);
    executionThread.setUncaughtExceptionHandler(new UncaughtExceptionHandler() {
      @Override
      public void uncaughtException(Thread thread, Throwable e) {
        thrownByExecutionThread = e;
      }
    });
    executionThread.start();
  }

  private static void throwIfSet(Throwable t) throws Throwable {
    if (t != null) {
      throw t;
    }
  }

  public void testStopUnstartedService() throws Exception {
    NoOpService service = new NoOpService();
    RecordingListener listener = RecordingListener.record(service);

    service.stopAsync();
    assertEquals(State.TERMINATED, service.state());

    try {
      service.startAsync();
      fail();
    } catch (IllegalStateException expected) {}
    assertEquals(State.TERMINATED, Iterables.getOnlyElement(listener.getStateHistory()));
  }

  public void testFailingServiceStartAndWait() throws Exception {
    StartFailingService service = new StartFailingService();
    RecordingListener listener = RecordingListener.record(service);

    try {
      service.startAsync().awaitRunning();
      fail();
    } catch (IllegalStateException e) {
      assertEquals(EXCEPTION, service.failureCause());
      assertEquals(EXCEPTION, e.getCause());
    }
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.FAILED),
        listener.getStateHistory());
  }

  public void testFailingServiceStopAndWait_stopFailing() throws Exception {
    StopFailingService service = new StopFailingService();
    RecordingListener listener = RecordingListener.record(service);

    service.startAsync().awaitRunning();
    try {
      service.stopAsync().awaitTerminated();
      fail();
    } catch (IllegalStateException e) {
      assertEquals(EXCEPTION, service.failureCause());
      assertEquals(EXCEPTION, e.getCause());
    }
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.STOPPING,
            State.FAILED),
        listener.getStateHistory());
  }

  public void testFailingServiceStopAndWait_runFailing() throws Exception {
    RunFailingService service = new RunFailingService();
    RecordingListener listener = RecordingListener.record(service);

    service.startAsync();
    try {
      service.awaitRunning();
      fail();
    } catch (IllegalStateException e) {
      assertEquals(EXCEPTION, service.failureCause());
      assertEquals(EXCEPTION, e.getCause());
    }
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.FAILED),
        listener.getStateHistory());
  }

  public void testThrowingServiceStartAndWait() throws Exception {
    StartThrowingService service = new StartThrowingService();
    RecordingListener listener = RecordingListener.record(service);

    try {
      service.startAsync().awaitRunning();
      fail();
    } catch (IllegalStateException e) {
      assertEquals(service.exception, service.failureCause());
      assertEquals(service.exception, e.getCause());
    }
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.FAILED),
        listener.getStateHistory());
  }

  public void testThrowingServiceStopAndWait_stopThrowing() throws Exception {
    StopThrowingService service = new StopThrowingService();
    RecordingListener listener = RecordingListener.record(service);

    service.startAsync().awaitRunning();
    try {
      service.stopAsync().awaitTerminated();
      fail();
    } catch (IllegalStateException e) {
      assertEquals(service.exception, service.failureCause());
      assertEquals(service.exception, e.getCause());
    }
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.STOPPING,
            State.FAILED),
        listener.getStateHistory());
  }

  public void testThrowingServiceStopAndWait_runThrowing() throws Exception {
    RunThrowingService service = new RunThrowingService();
    RecordingListener listener = RecordingListener.record(service);

    service.startAsync();
    try {
      service.awaitTerminated();
      fail();
    } catch (IllegalStateException e) {
      assertEquals(service.exception, service.failureCause());
      assertEquals(service.exception, e.getCause());
    }
    assertEquals(
        ImmutableList.of(
            State.STARTING,
            State.RUNNING,
            State.FAILED),
        listener.getStateHistory());
  }

  public void testFailureCause_throwsIfNotFailed() {
    StopFailingService service = new StopFailingService();
    try {
      service.failureCause();
      fail();
    } catch (IllegalStateException e) {
      // expected
    }
    service.startAsync().awaitRunning();
    try {
      service.failureCause();
      fail();
    } catch (IllegalStateException e) {
      // expected
    }
    try {
      service.stopAsync().awaitTerminated();
      fail();
    } catch (IllegalStateException e) {
      assertEquals(EXCEPTION, service.failureCause());
      assertEquals(EXCEPTION, e.getCause());
    }
  }

  public void testAddListenerAfterFailureDoesntCauseDeadlock() throws InterruptedException {
    final StartFailingService service = new StartFailingService();
    service.startAsync();
    assertEquals(State.FAILED, service.state());
    service.addListener(new RecordingListener(service), directExecutor());
    Thread thread = new Thread() {
      @Override public void run() {
        // Internally stopAsync() grabs a lock, this could be any such method on AbstractService.
        service.stopAsync();
      }
    };
    thread.start();
    thread.join(LONG_TIMEOUT_MILLIS);
    assertFalse(thread + " is deadlocked", thread.isAlive());
  }

  public void testListenerDoesntDeadlockOnStartAndWaitFromRunning() throws Exception {
    final NoOpThreadedService service = new NoOpThreadedService();
    service.addListener(new Listener() {
      @Override public void running() {
        service.awaitRunning();
      }
    }, directExecutor());
    service.startAsync().awaitRunning(LONG_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS);
    service.stopAsync();
  }

  public void testListenerDoesntDeadlockOnStopAndWaitFromTerminated() throws Exception {
    final NoOpThreadedService service = new NoOpThreadedService();
    service.addListener(new Listener() {
      @Override public void terminated(State from) {
        service.stopAsync().awaitTerminated();
      }
    }, directExecutor());
    service.startAsync().awaitRunning();

    Thread thread = new Thread() {
      @Override public void run() {
        service.stopAsync().awaitTerminated();
      }
    };
    thread.start();
    thread.join(LONG_TIMEOUT_MILLIS);
    assertFalse(thread + " is deadlocked", thread.isAlive());
  }

  private static class NoOpThreadedService extends AbstractExecutionThreadService {
    final CountDownLatch latch = new CountDownLatch(1);
    @Override protected void run() throws Exception {
      latch.await();
    }
    @Override protected void triggerShutdown() {
      latch.countDown();
    }
  }

  private static class StartFailingService extends AbstractService {
    @Override protected void doStart() {
      notifyFailed(EXCEPTION);
    }

    @Override protected void doStop() {
      fail();
    }
  }

  private static class RunFailingService extends AbstractService {
    @Override protected void doStart() {
      notifyStarted();
      notifyFailed(EXCEPTION);
    }

    @Override protected void doStop() {
      fail();
    }
  }

  private static class StopFailingService extends AbstractService {
    @Override protected void doStart() {
      notifyStarted();
    }

    @Override protected void doStop() {
      notifyFailed(EXCEPTION);
    }
  }

  private static class StartThrowingService extends AbstractService {

    final RuntimeException exception = new RuntimeException("deliberate");

    @Override protected void doStart() {
      throw exception;
    }

    @Override protected void doStop() {
      fail();
    }
  }

  private static class RunThrowingService extends AbstractService {

    final RuntimeException exception = new RuntimeException("deliberate");

    @Override protected void doStart() {
      notifyStarted();
      throw exception;
    }

    @Override protected void doStop() {
      fail();
    }
  }

  private static class StopThrowingService extends AbstractService {

    final RuntimeException exception = new RuntimeException("deliberate");

    @Override protected void doStart() {
      notifyStarted();
    }

    @Override protected void doStop() {
      throw exception;
    }
  }

  private static class RecordingListener extends Listener {
    static RecordingListener record(Service service) {
      RecordingListener listener = new RecordingListener(service);
      service.addListener(listener, directExecutor());
      return listener;
    }

    final Service service;

    RecordingListener(Service service) {
      this.service = service;
    }

    @GuardedBy("this")
    final List<State> stateHistory = Lists.newArrayList();
    final CountDownLatch completionLatch = new CountDownLatch(1);

    ImmutableList<State> getStateHistory() throws Exception {
      completionLatch.await();
      synchronized (this) {
        return ImmutableList.copyOf(stateHistory);
      }
    }

    @Override public synchronized void starting() {
      assertTrue(stateHistory.isEmpty());
      assertNotSame(State.NEW, service.state());
      stateHistory.add(State.STARTING);
    }

    @Override public synchronized void running() {
      assertEquals(State.STARTING, Iterables.getOnlyElement(stateHistory));
      stateHistory.add(State.RUNNING);
      service.awaitRunning();
      assertNotSame(State.STARTING, service.state());
    }

    @Override public synchronized void stopping(State from) {
      assertEquals(from, Iterables.getLast(stateHistory));
      stateHistory.add(State.STOPPING);
      if (from == State.STARTING) {
        try {
          service.awaitRunning();
          fail();
        } catch (IllegalStateException expected) {
          assertNull(expected.getCause());
          assertTrue(expected.getMessage().equals(
              "Expected the service " + service + " to be RUNNING, but was STOPPING"));
        }
      }
      assertNotSame(from, service.state());
    }

    @Override public synchronized void terminated(State from) {
      assertEquals(from, Iterables.getLast(stateHistory, State.NEW));
      stateHistory.add(State.TERMINATED);
      assertEquals(State.TERMINATED, service.state());
      if (from == State.NEW) {
        try {
          service.awaitRunning();
          fail();
        } catch (IllegalStateException expected) {
          assertNull(expected.getCause());
          assertTrue(expected.getMessage().equals(
              "Expected the service " + service + " to be RUNNING, but was TERMINATED"));
        }
      }
      completionLatch.countDown();
    }

    @Override public synchronized void failed(State from, Throwable failure) {
      assertEquals(from, Iterables.getLast(stateHistory));
      stateHistory.add(State.FAILED);
      assertEquals(State.FAILED, service.state());
      assertEquals(failure, service.failureCause());
      if (from == State.STARTING) {
        try {
          service.awaitRunning();
          fail();
        } catch (IllegalStateException e) {
          assertEquals(failure, e.getCause());
        }
      }
      try {
        service.awaitTerminated();
        fail();
      } catch (IllegalStateException e) {
        assertEquals(failure, e.getCause());
      }
      completionLatch.countDown();
    }
  }

  public void testNotifyStartedWhenNotStarting() {
    AbstractService service = new DefaultService();
    try {
      service.notifyStarted();
      fail();
    } catch (IllegalStateException expected) {}
  }

  public void testNotifyStoppedWhenNotRunning() {
    AbstractService service = new DefaultService();
    try {
      service.notifyStopped();
      fail();
    } catch (IllegalStateException expected) {}
  }

  public void testNotifyFailedWhenNotStarted() {
    AbstractService service = new DefaultService();
    try {
      service.notifyFailed(new Exception());
      fail();
    } catch (IllegalStateException expected) {}
  }

  public void testNotifyFailedWhenTerminated() {
    NoOpService service = new NoOpService();
    service.startAsync().awaitRunning();
    service.stopAsync().awaitTerminated();
    try {
      service.notifyFailed(new Exception());
      fail();
    } catch (IllegalStateException expected) {}
  }

  private static class DefaultService extends AbstractService {
    @Override protected void doStart() {}
    @Override protected void doStop() {}
  }

  private static final Exception EXCEPTION = new Exception();
}