}
}

func TestUnreadRuneAtEOF(t *testing.T) {
	// UnreadRune/ReadRune should error at EOF (was a bug; used to panic)
	r := NewReader(strings.NewReader("x"))
	r.ReadRune()
	r.ReadRune()
	r.UnreadRune()
	_, _, err := r.ReadRune()
	if err == nil {
		t.Error("expected error at EOF")
	} else if err != io.EOF {
		t.Error("expected EOF; got", err)
	}
}

	c := b.buf[b.off]
	b.off++
	b.lastRead = opRead
	return c, nil
}

// ReadRune reads and returns the next UTF-8-encoded
// Unicode code point from the buffer.
// If no bytes are available, the error returned is io.EOF.
// If the bytes are an erroneous UTF-8 encoding, it
// consumes one byte and returns U+FFFD, 1.
func (b *Buffer) ReadRune() (r rune, size int, err error) {
	if b.empty() {

		t.Fatal("UnreadRune at EOF: got no error")
	}
	if _, _, err := buf.ReadRune(); err == nil {
		t.Fatal("ReadRune at EOF: got no error")
	}
	if err := buf.UnreadRune(); err == nil {
		t.Fatal("UnreadRune after ReadRune at EOF: got no error")
	}

	// check not at EOF
	buf.Write(b)
	for r := rune(0); r < NRune; r++ {
		r1, size, _ := buf.ReadRune()
		if err := buf.UnreadRune(); err != nil {