static String createRandomPrefix() {
        return Integer.toString(RANDOM.nextInt(MAX_RANDOM_PART_VALUE), ALL_DIGITS_AND_LETTERS_RADIX)
    }

    static GpgCmdAndVersion getAvailableGpg() {
        return tryRun("gpg")
    }

    static GpgCmdAndVersion tryRun(String cmd) {
        try {
            String output = "${cmd} --version".execute().text

class SigningTestPreconditions {

    static final class GpgAvailable implements TestPrecondition {
        @Override
        boolean isSatisfied() throws Exception {
            return GpgCmdFixture.getAvailableGpg() != null
        }
    }