b := bytes.NewBuffer(nil)
	w := NewWriter(b)
	for i := 0; i < 5; i++ {
		_, err := w.Create("")
		if err != nil {
			t.Fatalf("Writer.Create failed: %s", err)
		}
	}
	if err := w.Close(); err != nil {
		t.Fatalf("Writer.Close failed: %s", err)
	}
	r, err := NewReader(bytes.NewReader(b.Bytes()), int64(b.Len()))
	if err != nil {
		t.Fatalf("NewReader failed: %s", err)
	}

			Gid:      1000,
			ModTime:  time.Unix(1486082191, 0),
			Typeflag: '0',
			Uname:    "rawr",
			Gname:    "dsnet",
			Format:   FormatGNU,
		}},
	}, {
		// This archive was generated by Writer but is readable by both
		// GNU and BSD tar utilities.
		// The archive generated by GNU is nearly byte-for-byte identical
		// to the Go version except the Go version sets a negative Devminor

func TestReaderCopyNothing(t *testing.T) {
	type nErr struct {
		n   int64
		err error
	}
	type justReader struct {
		io.Reader
	}
	type justWriter struct {
		io.Writer
	}
	discard := justWriter{io.Discard} // hide ReadFrom

	var with, withOut nErr
	with.n, with.err = io.Copy(discard, NewReader(nil))
	withOut.n, withOut.err = io.Copy(discard, justReader{NewReader(nil)})