}
	for _, tt := range tests {
		if got := IndexRune([]byte(tt.in), tt.rune); got != tt.want {
			t.Errorf("IndexRune(%q, %d) = %v; want %v", tt.in, tt.rune, got, tt.want)
		}
	}

	haystack := []byte("test世界")
	allocs := testing.AllocsPerRun(1000, func() {
		if i := IndexRune(haystack, 's'); i != 2 {
			t.Fatalf("'s' at %d; want 2", i)
		}
		if i := IndexRune(haystack, '世'); i != 4 {

	return bytealg.LastIndexByte(s, c)
}

// IndexRune interprets s as a sequence of UTF-8-encoded code points.
// It returns the byte index of the first occurrence in s of the given rune.
// It returns -1 if rune is not present in s.
// If r is [utf8.RuneError], it returns the first instance of any
// invalid UTF-8 byte sequence.
func IndexRune(s []byte, r rune) int {
	const haveFastIndex = bytealg.MaxBruteForce > 0

// has been uploaded using the S3 singlepart API.
//
// Parts may panic if the ETag is an invalid multipart
// ETag.
func (e ETag) Parts() int {
	if !e.IsMultipart() {
		return 1
	}

	n := bytes.IndexRune(e, '-')
	parts, err := strconv.Atoi(string(e[n+1:]))
	if err != nil {
		panic(err) // malformed ETag
	}
	return parts
}

// Format returns an ETag that is formatted as specified
// by AWS S3.
//

result parameters, the function body's statement list must end in
a <a href="#Terminating_statements">terminating statement</a>.
</p>

<pre>
func IndexRune(s string, r rune) int {
	for i, c := range s {
		if c == r {
			return i
		}
	}
	// invalid: missing return statement
}
</pre>

<p>

pkg bytes, func Index([]uint8, []uint8) int
pkg bytes, func IndexAny([]uint8, string) int
pkg bytes, func IndexByte([]uint8, uint8) int
pkg bytes, func IndexFunc([]uint8, func(int32) bool) int
pkg bytes, func IndexRune([]uint8, int32) int
pkg bytes, func Join([][]uint8, []uint8) []uint8
pkg bytes, func LastIndex([]uint8, []uint8) int
pkg bytes, func LastIndexAny([]uint8, string) int