@Override
  public SeekableByteChannel truncate(long size) throws IOException {
    delegate.truncate(size);
    return this;
  }
@Test
  public void testTruncate() throws IOException {
    int newSize = 5;
    channelUnderTest.truncate(newSize);
    assertEquals(newSize, delegate.size());
    assertEquals(newSize, channelUnderTest.size());
  }