t.Errorf("#%d: got error %v; want EOF", rno, err)
		}
	}
}

// Test that UnreadRune fails if the preceding operation was not a ReadRune.
func TestUnreadRuneError(t *testing.T) {
	buf := make([]byte, 3) // All runes in this test are 3 bytes long
	r := NewReader(&StringReader{data: []string{"日本語日本語日本語"}})
	if r.UnreadRune() == nil {
		t.Error("expected error on UnreadRune from fresh buffer")
	}
	_, _, err := r.ReadRune()

		r, wid := utf8.DecodeRuneInString(s)
		s = s[wid:]
		if wid > 1 {
			if r == '\ufeff' {
				return false // BOMs are invisible and should not be quoted.
			}
			continue // All other multibyte runes are correctly encoded and assumed printable.
		}
		if r == utf8.RuneError {
			return false
		}
		if (r < ' ' && r != '\t') || r == '`' || r == '\u007F' {
			return false
		}
	}
	return true
}

			t.Fatalf("ReadRune(%U) after UnreadRune got %U,%d not %U,%d (err=%s)", r, r2, nbytes, r, size, err)
		}
	}
}

func TestWriteInvalidRune(t *testing.T) {
	// Invalid runes, including negative ones, should be written as
	// utf8.RuneError.
	for _, r := range []rune{-1, utf8.MaxRune + 1} {
		var buf Buffer
		buf.WriteRune(r)

		if err != nil {
			return err
		}
		fi, err := src.Stat()
		if err != nil {
			src.Close()
			return err
		}
		// Note: Not using %-16.16s format because we care
		// about bytes, not runes.
		name := fi.Name()
		if len(name) > 16 {
			name = name[:16]
		} else {
			name += strings.Repeat(" ", 16-len(name))
		}
		size := fi.Size()
		fmt.Fprintf(w, "%s%-12d%-6d%-6d%-8o%-10d`\n",

				// RE2's \B considers every byte position,
				// so it sees 'not word boundary' in the
				// middle of UTF-8 sequences. This package
				// only considers the positions between runes,
				// so it disagrees. Skip those cases.
				continue
			}
			res := strings.Split(line, ";")
			if len(res) != len(run) {
				t.Fatalf("%s:%d: have %d test results, want %d", file, lineno, len(res), len(run))

		n := int((*arrayType)(unsafe.Pointer(v.typ())).Len)
		return unsafe.Slice(p, n)
	}
	panic(&ValueError{"reflect.Value.Bytes", v.kind()})
}

// runes returns v's underlying value.
// It panics if v's underlying value is not a slice of runes (int32s).
func (v Value) runes() []rune {
	v.mustBe(Slice)
	if v.typ().Elem().Kind() != abi.Int32 {
		panic("reflect.Value.Bytes of non-rune slice")
	}

	offs := s.offset

	// Optimize for the common case of an ASCII identifier.
	//
	// Ranging over s.src[s.rdOffset:] lets us avoid some bounds checks, and
	// avoids conversions to runes.
	//
	// In case we encounter a non-ASCII character, fall back on the slower path
	// of calling into s.next().
	for rdOffset, b := range s.src[s.rdOffset:] {

}

// WriteRune writes a single Unicode code point, returning
// the number of bytes written and any error.
func (b *Writer) WriteRune(r rune) (size int, err error) {
	// Compare as uint32 to correctly handle negative runes.
	if uint32(r) < utf8.RuneSelf {
		err = b.WriteByte(byte(r))
		if err != nil {
			return 0, err
		}
		return 1, nil
	}
	if b.err != nil {
		return 0, b.err
	}
	n := b.Available()

	i := bytes.IndexAny(s, delimEnds[c.delim])
	if i == -1 {
		i = len(s)
	}
	if c.delim == delimSpaceOrTagEnd {
		// https://www.w3.org/TR/html5/syntax.html#attribute-value-(unquoted)-state
		// lists the runes below as error characters.
		// Error out because HTML parsers may differ on whether
		// "<a id= onclick=f("     ends inside id's or onclick's value,
		// "<a class=`foo "        ends inside a value,

	}

	defer func(w uint64) {
		p.scanner.Whitespace = w
	}(p.scanner.Whitespace)
	p.scanner.Whitespace = 0

	// We should now have p.tok pointing to the final newline.
	// The next runes from the scanner should be the type data.

	var sb strings.Builder
	for sb.Len() < total {
		r := p.scanner.Next()
		if r == scanner.EOF {
			p.error("unexpected EOF")
		}
		sb.WriteRune(r)
	}