t.Errorf("test %d, unexpected Close error: %v", i, err)
		}

		// The prefix field should never appear in the GNU format.
		var blk block
		copy(blk[:], b.Bytes())
		prefix := string(blk.toUSTAR().prefix())
		prefix, _, _ = strings.Cut(prefix, "\x00") // Truncate at the NUL terminator
		if blk.getFormat() == FormatGNU && len(prefix) > 0 && strings.HasPrefix(name, prefix) {
			t.Errorf("test %d, found prefix in GNU format: %s", i, prefix)

	// 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)
	}
}