int originalCount = getMultiset().count(e0());
    assertEquals("old count", originalCount, getMultiset().remove(e0(), 0));
    expectUnchanged();
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemove_occurrences_present() {
    assertEquals(
        "multiset.remove(present, 2) didn't return the old count",
        1,
        getMultiset().remove(e0(), 2));

                setValue(e, key, value, now);
                newCount = this.count; // count remains unchanged
              } else {
                setValue(e, key, value, now);
                newCount = this.count + 1;
              }
              this.count = newCount; // write-volatile
              evictEntries(e);
              return null;

    assertEquals(3, multiset.size());
    assertEquals(2, multiset.count("foo"));
    assertEquals("[foo x 2, bar]", multiset.toString());
  }

  public void testCreateWithSize() {
    Multiset<String> multiset = LinkedHashMultiset.create(50);
    multiset.add("foo", 2);
    multiset.add("bar");
    assertEquals(3, multiset.size());
    assertEquals(2, multiset.count("foo"));
    assertEquals("[foo x 2, bar]", multiset.toString());

      fail();
    } catch (NullPointerException expected) {
    }
  }

  private static class CountingIterable implements Iterable<String> {
    int count = 0;

    @Override
    public Iterator<String> iterator() {
      count++;
      return asList("a", "b", "a").iterator();
    }
  }

  public void testCopyOf_plainIterable() {
    CountingIterable iterable = new CountingIterable();

    Multiset<String> ms2 = HashMultiset.create(Arrays.asList("a", "b", "b", "b"));
    Multiset<String> diff = Multisets.difference(ms1, ms2);
    assertThat(diff).contains("a");
    assertEquals(0, diff.count("b"));
    assertEquals(1, diff.count("a"));
    assertFalse(diff.contains("b"));
    assertTrue(diff.contains("a"));
  }

  public void testDifferenceEmptyNonempty() {
    Multiset<String> ms1 = HashMultiset.create();

    }

    @Override
    Multiset<E> delegate() {
      return (Multiset<E>) super.delegate();
    }

    @Override
    public int count(@CheckForNull Object o) {
      synchronized (mutex) {
        return delegate().count(o);
      }
    }

    @Override
    public int add(@ParametricNullness E e, int n) {
      synchronized (mutex) {
        return delegate().add(e, n);

        throw new RuntimeException("Unexpected interrupt while waiting for latch", ie);
      }
    } while (System.nanoTime() - deadline < 0);
    throw formatRuntimeException(
        "Latch failed to count down within %d second timeout", timeoutSeconds);
  }

  /**
   * Creates a garbage object that counts down the latch in its finalizer. Sequestered into a

   *
   * <p>This is useful when a varargs method needs to use a signature such as {@code (Foo firstFoo,
   * Foo... moreFoos)}, in order to avoid overload ambiguity or to enforce a minimum argument count.
   *
   * <p>The returned list is serializable and implements {@link RandomAccess}.
   *
   * @param first the first element
   * @param rest an array of additional elements, possibly empty

    CollectionSize.ANY,
    ALLOWS_NULL_VALUES,
    SUPPORTS_REMOVE,
    CollectionFeature.SUPPORTS_ITERATOR_REMOVE,
    MultisetTestSuiteBuilder.NoRecurse.NO_ENTRY_SET, // Cannot create entries with count > 1
  };

  static final Supplier<TreeSet<String>> STRING_TREESET_FACTORY =
      new Supplier<TreeSet<String>>() {
        @Override
        public TreeSet<String> get() {

    private int count;
    private final AsyncFunction<X, V> delegate;

    public AsyncFunctionSpy(AsyncFunction<X, V> delegate) {
      this.delegate = delegate;
    }

    @Override
    public final ListenableFuture<V> apply(X t) throws Exception {
      count++;
      return delegate.apply(t);
    }

    void verifyCallCount(int expected) {