}
	_, err = NewReader(bytes.NewReader(b), size)
	if err != ErrFormat {
		t.Errorf("sigs: error=%v, want %v", err, ErrFormat)
	}

	// negative size
	_, err = NewReader(bytes.NewReader([]byte("foobar")), -1)
	if err == nil {
		t.Errorf("archive/zip.NewReader: expected error when negative size is passed")
	}
}

func messWith(fileName string, corrupter func(b []byte)) (r io.ReaderAt, size int64) {