javascript - Unit test request-promise, promise() is not a function -

i trying unit test function sinon/mocha uses request-promise. attach .promise() allow access bluebird promise methods.

according request-promise readme:

rp(...).promise() or e.g. rp.head(...).promise() returns underlying promise can access full bluebird api 

mymodule.js var requestpromise = require('request-promise');

function requestwrapper(opts) {    // adds .promise() allow access bluebird methods    return requestpromise(opts).promise(); }  module.exports = requestwrapper; 

unit test

var promise = require('bluebird'); var requestpromise = sinon.stub().returns(promise.resolve()); var rewire = require('rewire'); var mymodule = rewire('./mymodule');  mymodule.__set__({   requestpromise: requestpromise });  describe('mymodule', function() {   var testpromise;    it('should...', function() {       testpromise = mymodule.requestwrapper({ method: 'get', url: 'http://someurl.com' })   }); }); 

error

i'm getting following error: typeerror: requestpromise(...).promise not function.