return new ExecResult(stdout, stderr, returnCode);
    }

    private static String getStdout(String[] command) throws IOException, InterruptedException, ExecutionException {
        ExecResult execResult = exec(command);
        if (execResult.returnCode() != 0) {
            throw new AssertionError(String.join(" ", command) + " failed with return code: " + execResult);
        }

        ExecResult r = exec(cmd);
        if (r.exitCode != 0) {
            throw new AssertionError(String.join(" ", cmd) + " failed: " + r);
        }
        return r.stdout;
    }

    private static final class ExecResult {
        final int exitCode;
        final String stdout;
        final String stderr;

        ExecResult(int exitCode, String stdout, String stderr) {

        ExecResult r = exec(cmd);
        if (r.exitCode() != 0) {
            throw new AssertionError(String.join(" ", cmd) + " failed: " + r);
        }
    }

    private static String stdout(String... cmd) throws IOException, InterruptedException, ExecutionException {
        ExecResult r = exec(cmd);
        if (r.exitCode() != 0) {