@Test
public void canNotCalculateTreeHashForMissingFile() throws Exception {

    final File file = new File("notexisting.txt");
    final OptionSet options = optionParser.parse("--calculate", file.getAbsolutePath());
    // TODO how to verify this call? output is only into log
    new TreeHashArchiveCommand(client, sqs, sns).exec(options, optionParser);
}