}
	// Buffer is now empty; reset.
	b.Reset()
	return n, nil
}

// WriteByte appends the byte c to the buffer, growing the buffer as needed.
// The returned error is always nil, but is included to match [bufio.Writer]'s
// WriteByte. If the buffer becomes too large, WriteByte will panic with
// [ErrTooLarge].
func (b *Buffer) WriteByte(c byte) error {
	b.lastRead = opInvalid
	m, ok := b.tryGrowByReslice(1)
	if !ok {

		n, err := buf.Write(testBytes[0:1])
		if want := 1; err != nil || n != want {
			t.Errorf("Write: got (%d, %v), want (%d, %v)", n, err, want, nil)
		}
		check(t, "TestBasicOperations (4)", &buf, "a")

		buf.WriteByte(testString[1])
		check(t, "TestBasicOperations (5)", &buf, "ab")

		n, err = buf.Write(testBytes[2:26])
		if want := 24; err != nil || n != want {
			t.Errorf("Write: got (%d, %v), want (%d, %v)", n, err, want, nil)

					if i == len(in) {
						break
					}
				}
				if len(old) == 0 {
					_, length := utf8.DecodeRune(in[i:])
					out.Write(in[i : i+length])
					i += length
				} else {
					out.WriteByte(in[i])
					i++
				}
			}
			if len(old) == 0 && n != 0 {
				out.Write(new)
			}
			return out.Bytes()
		}