}
	// check empty or full
	if rb.IsEmpty() {
		t.Fatalf("expect IsEmpty is false but got true")
	}
	if rb.IsFull() {
		t.Fatalf("expect IsFull is false but got true")
	}

	// write to, isFull
	err = rb.WriteByte('b')
	if err != nil {
		t.Fatalf("WriteByte failed: %v", err)
	}
	if rb.Length() != 2 {

		copy(buf[c1:], r.buf[0:c2])
	}

	return buf
}

// IsFull returns this ringbuffer is full.
func (r *RingBuffer) IsFull() bool {
	r.mu.Lock()
	defer r.mu.Unlock()

	return r.isFull
}

// IsEmpty returns this ringbuffer is empty.
func (r *RingBuffer) IsEmpty() bool {
	r.mu.Lock()
	defer r.mu.Unlock()

	return !r.isFull && r.w == r.r
}

    // True if getValue never returns null.
    private boolean isFull() {
      return size == keyToIndex().size();
    }

    K getKey(int index) {
      return keyToIndex().keySet().asList().get(index);
    }

    abstract @Nullable V getValue(int keyIndex);

    @Override
    ImmutableSet<K> createKeySet() {
      return isFull() ? keyToIndex().keySet() : super.createKeySet();
    }

	Store         Store[I]
	CommitTimeout time.Duration
	Log           logger
}

// Add adds the item to the batch
func (b *Batch[I]) Add(item I) error {
	b.Lock()
	defer b.Unlock()

	if b.isFull() {
		if b.store == nil {
			return ErrBatchFull
		}
		// commit batch to store
		if err := b.commit(); err != nil {
			return err
		}
	}

	b.items = append(b.items, item)
	return nil
}

    // True if getValue never returns null.
    private boolean isFull() {
      return size == keyToIndex().size();
    }

    K getKey(int index) {
      return keyToIndex().keySet().asList().get(index);
    }

    abstract @Nullable V getValue(int keyIndex);

    @Override
    ImmutableSet<K> createKeySet() {
      return isFull() ? keyToIndex().keySet() : super.createKeySet();
    }

   *
   * <p><b>Discouraged:</b> Prefer using either {@code x -> x == null} or {@code Objects::isNull},
   * but note that lambdas and method references do not have human-readable {@link #toString()}
   * representations and are not serializable.
   */
  public static <T extends @Nullable Object> Predicate<T> isNull() {
    return ObjectPredicate.IS_NULL.withNarrowedType();
  }

  /**

   *
   * <p><b>Discouraged:</b> Prefer using either {@code x -> x == null} or {@code Objects::isNull},
   * but note that lambdas and method references do not have human-readable {@link #toString()}
   * representations and are not serializable.
   */
  public static <T extends @Nullable Object> Predicate<T> isNull() {
    return ObjectPredicate.IS_NULL.withNarrowedType();
  }

  /**

    assertThat(map.getInstance(Integer.class)).isNull();

    map.putInstance(Long.class, null);
    assertTrue(map.containsKey(TypeToken.of(Long.class)));
    assertTrue(map.entrySet().contains(immutableEntry(TypeToken.of(Long.class), null)));
    assertThat(map.get(TypeToken.of(Long.class))).isNull();
    assertThat(map.getInstance(Long.class)).isNull();
  }

    assertThat(spec.initialCapacity).isNull();
    assertThat(spec.maximumSize).isNull();
    assertThat(spec.maximumWeight).isNull();
    assertThat(spec.concurrencyLevel).isNull();
    assertThat(spec.keyStrength).isNull();
    assertThat(spec.valueStrength).isNull();
    assertThat(spec.writeExpirationTimeUnit).isNull();
    assertThat(spec.accessExpirationTimeUnit).isNull();

    assertThat(request.body).isNull()
  }

  @Test
  fun userAgent() {
    val request = fromArgs("-A", "foo", "http://example.com").createRequest()
    assertThat(request.method).isEqualTo("GET")
    assertThat(request.url.toString()).isEqualTo("http://example.com/")
    assertThat(request.header("User-Agent")).isEqualTo("foo")
    assertThat(request.body).isNull()
  }

  @Test