javascript - Stubbing a function in sinon to return different value every time it is called -

i have function shown below:

function test(parms) {         var self = this;         return this.test2(parms)         .then(function (data) {             if (data) {                 return ;             }             else {                 return bluebird.delay(1000)                 .then(self.test.bind(self, parms));             }         }.bind(self));     }; 

i trying write unit tests function. using sinon.stub mock functionality of function test2.

i wrote test case test2 returns true , therefore test function completes execution. want test case on first instance test2 returns false, waits delay , next time test2 returns true. wrote test case below:

var clock; var result; var test2stub; var count = 0;  before(function () {     clock = sinon.usefaketimers();     //object defined before     test2stub = sinon.stub(object,"test2", function () {         console.log("count is: " + count);         if (count === 0) {             return (bluebird.resolve(false));         }         else if (count === 1) {             return (bluebird.resolve(true));         }     });     clock.tick(1000);         object.test("xyz")     .then(function (data) {         result = data;     });     clock.tick(1000);     count = count + 1;     clock.tick(1000); });  after(function () {     test2stub.restore();     clock.restore(); });  it("result should undefined. check if test2 returned false first & true next",    function () {     expect(result).to.be.undefined; }); 

in logs shows count has value 0 only.

1. the code of test incorrect. never returns data on success. returns undefined. function should return data on success otherwise won't able use parameter next .then handler

   .then(function (data) {     if (data) {         return data;     } 

2. next make wrong assumptions function test. never return undefined. function rather dangerous , call forever in endless chain of promises until squeezes out not-null data test2.

3. one shouldn't launch test code in before or beforeeach section. before , after meant prepare environment faking timers , restoring them.
   1 reason calling tested code in it handler because promises should handled differently. handler should accept parameter indicates test asynchronous , the test engine gives timeout (usually 10 secs) complete. test expected either call done() indicate test successful or call done(error) if failed , there error object (or expect threw exception).
   should move fake timer after async operation started. in code first clock.tick useless.

4. there trick using faketimers. can move time manually doesn't move on own. first tick works well. promise executed. upon returning .delay(1000) promise, there no command move time forward. so, finish test correctly (not modify tested code) have stub bluebird.delay

i change stubs implementation , this

describe("test2", function(){     beforeeach(function(){         clock = sinon.usefaketimers();         test2stub = sinon.stub(object,"test2", function () {             console.log("count is: " + count);             return (bluebird.resolve((count++) > 0));         });         var _delay = bluebird.delay.bind(bluebird);         bluebirddelaystub = sinon.stub(bluebird,"delay", function (delay) {             var promise = _delay(delay);             clock.tick(1000);             return promise;         });     })     it("should return true", function (done) {         object.test("xyz")         .then(function (data) {             expect(data).to.be.true;             expect(count).to.equal(2);             done();         })         .catch(function(err){             done(err);         });         clock.tick(1000);     });      after(function () {         test2stub.restore();         clock.restore();                 bluebirddelaystub.restore();     });     }) 

ps verified code under node.js 0.10.35 , bluebird 2.9.34