truffle/test/sources/exec/script.js

Truffle - Simple development framework for Ethereum

const Executable = artifacts.require("Executable");

const exec = function () {
  Executable.new()
    .then(instance => instance.x())
    .then(val => {
      console.log(parseInt(val));
      process.exit(0);
    })
    .catch(() => process.exit(1));
};

module.exports = exec;