//		if err := os.WriteFile("/tmp/big.zip", bigZip, 0666); err != nil {
//			log.Fatal(err)
//		}
//
//		biggerZip := makeZip("big.zip", bytes.NewReader(bigZip))
//		if err := os.WriteFile("/tmp/bigger.zip", biggerZip, 0666); err != nil {
//			log.Fatal(err)
//		}
//
//		biggestZip := makeZip("bigger.zip", bytes.NewReader(biggerZip))
//		if err := os.WriteFile("/tmp/biggest.zip", biggestZip, 0666); err != nil {

	rfw := &readFromWriter{}
	w := NewWriterSize(rfw, bufsize)

	const writeSize = 8
	if n, err := w.Write(input[:writeSize]); n != writeSize || err != nil {
		t.Errorf("w.Write(%v bytes) = %v, %v; want %v, nil", writeSize, n, err, writeSize)
	}
	n, err := w.ReadFrom(bytes.NewReader(input[writeSize:]))
	if wantn := len(input[writeSize:]); int(n) != wantn || err != nil {