for n, test := range scanTests {
		buf := strings.NewReader(test)
		s := NewScanner(buf)
		s.Split(ScanRunes)
		var i, runeCount int
		var expect rune
		// Use a string range loop to validate the sequence of runes.
		for i, expect = range test {
			if !s.Scan() {
				break
			}
			runeCount++
			got, _ := utf8.DecodeRune(s.Bytes())
			if got != expect {
				t.Errorf("#%d: %d: expected %q got %q", n, i, expect, got)
			}

// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
func Count(s, sep []byte) int {
	// special case
	if len(sep) == 0 {
		return utf8.RuneCount(s) + 1
	}
	if len(sep) == 1 {
		return bytealg.Count(s, sep[0])
	}
	n := 0
	for {
		i := Index(s, sep)
		if i == -1 {
			return n
		}
		n++
		s = s[i+len(sep):]
	}
}