### Question:
DataStream { @IntRange(from = 0) public int size() { return buffer.size(); } DataStream(); @SuppressWarnings("SimplifiableIfStatement") boolean write(@Nullable final byte[] data); boolean write(@Nullable final byte[] data,
						 @IntRange(from = 0) final int offset, @IntRange(from = 0) final int length); boolean write(@Nullable final Data data); @IntRange(from = 0) int size(); @NonNull byte[] toByteArray(); @NonNull Data toData();  }### Answer:
@Test public void size() { final DataStream stream = new DataStream(); stream.write(new byte[] { 0, 1, 2, 3, 4, 5, 6}); assertEquals(7, stream.size()); }