sb := strings.Split(strings.TrimSpace(hex.Dump(b)), "\n")
	for len(sa) > 0 && len(sb) > 0 {
		if sa[0] == sb[0] {
			ss = append(ss, identity+sa[0])
		} else {
			ss = append(ss, uniqueA+sa[0])
			ss = append(ss, uniqueB+sb[0])
		}
		sa, sb = sa[1:], sb[1:]
	}
	for len(sa) > 0 {
		ss = append(ss, uniqueA+sa[0])
		sa = sa[1:]
	}
	for len(sb) > 0 {
		ss = append(ss, uniqueB+sb[0])
		sb = sb[1:]
	}

	}()

	// write a zip file
	buf := new(bytes.Buffer)
	w := NewWriter(buf)

	for _, wt := range writeTests {
		testCreate(t, w, &wt)
	}

	if err := w.Close(); err != nil {
		t.Fatal(err)
	}

	// read it back
	r, err := NewReader(bytes.NewReader(buf.Bytes()), int64(buf.Len()))
	if err != nil {
		t.Fatal(err)
	}
	for i, wt := range writeTests {
		testReadFile(t, r.File[i], &wt)
	}
}