@CollectionSize.Require(absent = ZERO)
  public void testRemove_present() {
    int initialSize = getMap().size();
    assertEquals("remove(present) should return the associated value", v0(), getMap().remove(k0()));
    assertEquals(
        "remove(present) should decrease a map's size by one.", initialSize - 1, getMap().size());
    expectMissing(e0());
  }

  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplaceEntry_supportedPresent() {
    assertTrue(getMap().replace(k0(), v0(), v3()));
    expectReplacement(entry(k0(), v3()));
  }

    extends AbstractContainerTester<Map<K, V>, Entry<K, V>> {
  protected Map<K, V> getMap() {
    return container;
  }

  @Override
  protected Collection<Entry<K, V>> actualContents() {
    return getMap().entrySet();
  }

  /** @see AbstractContainerTester#resetContainer() */
  protected final void resetMap() {
    resetContainer();
  }

  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplaceEntry_supportedPresent() {
    assertTrue(getMap().replace(k0(), v0(), v3()));
    expectReplacement(entry(k0(), v3()));
  }

public class ConcurrentMapRemoveTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemove_supportedPresent() {
    assertTrue(getMap().remove(k0(), v0()));
    expectMissing(e0());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)

public class ConcurrentMapRemoveTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemove_supportedPresent() {
    assertTrue(getMap().remove(k0(), v0()));
    expectMissing(e0());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)

  public void testKeySetIteratorRemove() {
    int initialSize = getNumElements();
    Iterator<K> iterator = getMap().keySet().iterator();
    iterator.next();
    iterator.remove();
    assertEquals(initialSize - 1, getMap().size());
    assertEquals(initialSize - 1, getMap().inverse().size());
  }

@ElementTypesAreNonnullByDefault
public abstract class AbstractBiMapTester<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapTester<K, V> {

  @Override
  protected BiMap<K, V> getMap() {
    return (BiMap<K, V>) super.getMap();
  }

  static <K extends @Nullable Object, V extends @Nullable Object> Entry<V, K> reverseEntry(
      Entry<K, V> entry) {
    return Helpers.mapEntry(entry.getValue(), entry.getKey());
  }

    extends AbstractContainerTester<Map<K, V>, Entry<K, V>> {
  protected Map<K, V> getMap() {
    return container;
  }

  @Override
  protected Collection<Entry<K, V>> actualContents() {
    return getMap().entrySet();
  }

  /** @see AbstractContainerTester#resetContainer() */
  protected final void resetMap() {
    resetContainer();
  }

@ElementTypesAreNonnullByDefault
public class ConcurrentMapPutIfAbsentTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutIfAbsent_supportedAbsent() {
    assertNull("putIfAbsent(notPresent, value) should return null", putIfAbsent(e3()));