}

  public void testUnregister() {
    StringSubscriber s1 = new StringSubscriber();
    StringSubscriber s2 = new StringSubscriber();

    registry.register(s1);
    registry.register(s2);

    registry.unregister(s1);
    assertEquals(1, registry.getSubscribersForTesting(String.class).size());

    registry.unregister(s2);
    assertTrue(registry.getSubscribersForTesting(String.class).isEmpty());
  }

/** Tests for {@link MoreObjects}. */
@GwtCompatible(emulated = true)
public class MoreObjectsTest extends TestCase {
  public void testFirstNonNull_withNonNull() {
    String s1 = "foo";
    String s2 = MoreObjects.firstNonNull(s1, "bar");
    assertSame(s1, s2);

    Long n1 = 42L;
    Long n2 = MoreObjects.firstNonNull(null, n1);
    assertSame(n1, n2);

    Boolean b1 = true;
    Boolean b2 = MoreObjects.firstNonNull(b1, null);

  }

  public void testUnregister() {
    StringSubscriber s1 = new StringSubscriber();
    StringSubscriber s2 = new StringSubscriber();

    registry.register(s1);
    registry.register(s2);

    registry.unregister(s1);
    assertEquals(1, registry.getSubscribersForTesting(String.class).size());

    registry.unregister(s2);
    assertTrue(registry.getSubscribersForTesting(String.class).isEmpty());
  }

/** Tests for {@link MoreObjects}. */
@GwtCompatible(emulated = true)
public class MoreObjectsTest extends TestCase {
  public void testFirstNonNull_withNonNull() {
    String s1 = "foo";
    String s2 = MoreObjects.firstNonNull(s1, "bar");
    assertSame(s1, s2);

    Long n1 = 42L;
    Long n2 = MoreObjects.firstNonNull(null, n1);
    assertSame(n1, n2);

    Boolean b1 = true;
    Boolean b2 = MoreObjects.firstNonNull(b1, null);

    assertTrue(Objects.equal(1, 1));
    assertTrue(Objects.equal(null, null));

    // test distinct string objects
    String s1 = "foobar";
    String s2 = new String(s1);
    assertTrue(Objects.equal(s1, s2));

    assertFalse(Objects.equal(s1, null));
    assertFalse(Objects.equal(null, s1));
    assertFalse(Objects.equal("foo", "bar"));
    assertFalse(Objects.equal("1", 1));
  }

            state.put(
                rowFunction.apply(input),
                columnFunction.apply(input),
                valueFunction.apply(input),
                mergeFunction),
        (s1, s2) -> s1.combine(s2, mergeFunction),
        state -> state.toTable());
  }

  static <
          T extends @Nullable Object,
          R extends @Nullable Object,
          C extends @Nullable Object,
          V,

    assertThat(s1).isInstanceOf(Subscriber.SynchronizedSubscriber.class);

    // a thread-safe method should not create a synchronized subscriber
    Subscriber s2 = Subscriber.create(bus, this, getTestSubscriberMethod("threadSafeMethod"));
    assertThat(s2).isNotInstanceOf(Subscriber.SynchronizedSubscriber.class);
  }

  public void testInvokeSubscriberMethod_basicMethodCall() throws Throwable {

    String s1 = new String("a");
    String s2 = new String("a");
    assertEquals(s1, s2); // Stating the obvious.
    assertTrue(s1 != s2); // Stating the obvious.

    multiset.add(s1);
    assertTrue(multiset.contains(s1));
    assertFalse(multiset.contains(s2));
    assertEquals(1, multiset.count(s1));
    assertEquals(0, multiset.count(s2));

    multiset.add(s1);
    multiset.add(s2, 3);

    assertThat(s1).isInstanceOf(Subscriber.SynchronizedSubscriber.class);

    // a thread-safe method should not create a synchronized subscriber
    Subscriber s2 = Subscriber.create(bus, this, getTestSubscriberMethod("threadSafeMethod"));
    assertThat(s2).isNotInstanceOf(Subscriber.SynchronizedSubscriber.class);
  }

  public void testInvokeSubscriberMethod_basicMethodCall() throws Throwable {

    String s1 = new String("a");
    String s2 = new String("a");
    assertEquals(s1, s2); // Stating the obvious.
    assertTrue(s1 != s2); // Stating the obvious.

    multiset.add(s1);
    assertTrue(multiset.contains(s1));
    assertFalse(multiset.contains(s2));
    assertEquals(1, multiset.count(s1));
    assertEquals(0, multiset.count(s2));

    multiset.add(s1);
    multiset.add(s2, 3);