text: var mocha = require('mocha');
  var chai = require('chai');
  var sinon = require('sinon');
  var sinonChai = require("sinon-chai");
  var mockuire = require("mockuire")(module);
  var expect = chai.expect;
  chai.use(sinonChai);
  
  describe('df', function(){
      var subject;
  
      beforeEach(function () {
          subject = mockuire('../lib/df', {
              'child_process': {
                  execSync: function () {
                      return "25%\n100%\n0\n0";
                  }
              }
          });
      });
  
      it('should export a function', function () {
          expect(subject).to.be.a('function');
      });
  
      it('should return free disk space as a percentage', function () {
          expect(subject()).to.be.equal('75%');
      });
  
      it('should return false if an error is thrown', function () {
          subject = mockuire('../lib/df', {
              'child_process': {
                  execSync: function () {
                      throw new Error('boom');
                  }
              }
          });
          expect(subject()).to.be.false;
      });
  });
  