Simple Require / Mocking in JS

index.js

require('app-module-path').addPath(__dirname);

let mockery = require('mockery');
let fsMock = {
    stat: function (path, cb) { 
        console.log('mocked fs.stat'); 
    }
};
mockery.registerMock('fs', fsMock);
mockery.enable({ useCleanCache: true }); //toggle this line to actually run stat

require('t')('C:/temp', function(e, res) { 
  console.log(res); 
});

t.js

module.exports = function(dir, cb){
  let fs = require('fs');

  fs.stat(dir, cb);

};