@Test
public void testEmptyExcerpt_available() throws IOException {

    // length = 0.
    assertEquals(0, excerpt(makeEmpty(), 0, 0).available());
    assertEquals(0, excerpt(makeDigits(), 0, 0).available());
    // start == underlying length.
    assertEquals(0, excerpt(makeEmpty(), 0, 6).available());
    assertEquals(0, excerpt(makeDigits(), 10, 6).available());
    // start > underlying length.
    assertEquals(0, excerpt(makeEmpty(), 1, 0).available());;
    assertEquals(0, excerpt(makeDigits(), 10, 0).available());;
}