// Verify that custom promises work as advertised.varPrPromise=require('prfun');varassert=require('../assert');varfs=require('../fs');describe('Verify that custom promises can be used',function(){varoldPromise;before(function(){oldPromise=require('../_promise')();require('../_promise')(PrPromise);});after(function(){require('../_promise')(oldPromise);});it('exists should use the custom promise type',function(){varp=fs.exists('abc');assert.equal(pinstanceofPrPromise,true);});});