// This splitter will fail on last entry, after s.err==EOF.
	split := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
		advance, token, err = ScanWords(data, atEOF)
		if len(token) > 1 {
			if s.ErrOrEOF() != io.EOF {
				t.Fatal("not testing EOF")
			}
			err = testError
		}
		return
	}
	s.Split(split)
	for s.Scan() {
	}
	if s.Err() != testError {
		t.Fatal("wrong error:", s.Err())
	}