public void testConcat() {
    assertThat(Shorts.concat()).isEqualTo(EMPTY);
    assertThat(Shorts.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Shorts.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Shorts.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Shorts.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Shorts.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Shorts.concat(ARRAY1, ARRAY1, ARRAY1))

    assertEquals(EMPTY_STATS, cache.stats());

    cache.getUnchecked(one);
    assertEquals(EMPTY_STATS, cache.stats());

    Object two = new Object();
    cache.getUnchecked(two);
    assertEquals(EMPTY_STATS, cache.stats());

    Object three = new Object();
    cache.getUnchecked(three);
    assertEquals(EMPTY_STATS, cache.stats());
  }

  public void testRecordStats() {

                  protected Set<String> create(String[] elements) {
                    return Sets.union(Sets.<String>newHashSet(), Sets.<String>newHashSet());
                  }
                })
            .named("empty U empty")
            .withFeatures(
                CollectionSize.ZERO, CollectionFeature.NONE, CollectionFeature.ALLOWS_NULL_VALUES)
            .createTestSuite());

    suite.addTest(
        SetTestSuiteBuilder.using(

import junit.framework.TestCase;

/**
 * {@link LoadingCache} tests that deal with empty caches.
 *
 * @author mike nonemacher
 */

public class EmptyCachesTest extends TestCase {

  public void testEmpty() {
    for (LoadingCache<Object, Object> cache : caches()) {
      checkEmpty(cache);
    }
  }


  public void testInvalidate_empty() {
    for (LoadingCache<Object, Object> cache : caches()) {

   *
   * @param separatorPattern the pattern that determines whether a subsequence is a separator. This
   *     pattern may not match the empty string.
   * @return a splitter, with default settings, that uses this pattern
   * @throws IllegalArgumentException if {@code separatorPattern} matches the empty string
   */
  @GwtIncompatible // java.util.regex
  public static Splitter on(Pattern separatorPattern) {

  }

  @GwtIncompatible // ObjectArrays.newArray(Class, int)
  public void testNewArray_fromClass_Empty() {
    String[] empty = ObjectArrays.newArray(String.class, 0);
    assertEquals(String[].class, empty.getClass());
    assertThat(empty).isEmpty();
  }

  @GwtIncompatible // ObjectArrays.newArray(Class, int)
  public void testNewArray_fromClass_Nonempty() {

  }

  @SuppressWarnings("DoNotCall")
  public void testEmpty() {
    Iterator<Object> empty = new EmptyAbstractSequentialIterator<>();
    assertFalse(empty.hasNext());
    try {
      empty.next();
      fail();
    } catch (NoSuchElementException expected) {
    }
    try {
      empty.remove();
      fail();
    } catch (UnsupportedOperationException expected) {
    }
  }

  /**
   * Creates an empty {@code ArrayBlockingQueue} with the given (fixed) capacity and nonfair access
   * policy.
   */
  @J2ktIncompatible
  @GwtIncompatible // ArrayBlockingQueue
  public static <E> ArrayBlockingQueue<E> newArrayBlockingQueue(int capacity) {
    return new ArrayBlockingQueue<>(capacity);
  }

  // ArrayDeque

  /**
   * Creates an empty {@code ArrayDeque}.
   *
   * @since 12.0

   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.
   */
  @SuppressWarnings("unchecked")
  public static <T> Collector<T, ?, Optional<T>> toOptional() {
    return (Collector) TO_OPTIONAL;
  }

   * @param elements the elements that the multiset should contain
   * @throws IllegalArgumentException if {@code elements} is empty
   */
  public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) {
    Iterator<E> iterator = elements.iterator();
    checkArgument(iterator.hasNext(), "EnumMultiset constructor passed empty Iterable");
    EnumMultiset<E> multiset = new EnumMultiset<>(iterator.next().getDeclaringClass());