}

  public void testHash() throws IOException {
    HashCode expectedHash = Hashing.md5().hashBytes(expected);
    assertEquals(expectedHash, source.hash(Hashing.md5()));
  }

  public void testSlice_illegalArguments() {
    assertThrows(
        "expected IllegalArgumentException for call to slice with offset -1: " + source,
        IllegalArgumentException.class,
        () -> source.slice(-1, 0));

    assertThrows(