}

func (w *teststringwriter) WriteString(s string) (int, error) {
	w.writeString += s
	return len(s), nil
}

func (w *teststringwriter) check(t *testing.T, write, writeString string) {
	t.Helper()
	if w.write != write {
		t.Errorf("write: expected %q, got %q", write, w.write)
	}
	if w.writeString != writeString {
		t.Errorf("writeString: expected %q, got %q", writeString, w.writeString)
	}
}

	if !ok {
		m = b.grow(len(p))
	}
	return copy(b.buf[m:], p), nil
}

// WriteString appends the contents of s to the buffer, growing the buffer as
// needed. The return value n is the length of s; err is always nil. If the
// buffer becomes too large, WriteString will panic with [ErrTooLarge].
func (b *Buffer) WriteString(s string) (n int, err error) {
	b.lastRead = opInvalid
	m, ok := b.tryGrowByReslice(len(s))