How does one stub promise with sinon?

epitka picture epitka · Dec 12, 2013 · Viewed 71.8k times · Source

I have a data service with following function

function getInsureds(searchCriteria) {

    var deferred = $q.defer();

    insuredsSearch.get(searchCriteria,
        function (insureds) {
            deferred.resolve(insureds);
        },
        function (response) {
            deferred.reject(response);
        });

    return deferred.promise;
}

I want to test following function:

function search ()
{
  dataService
      .getInsureds(vm.searchCriteria)
      .then(function (response) {
           vm.searchCompleted = true;

            if (response.insureds.length > 100) {
              vm.searchResults = response.insureds.slice(0, 99);
            } else {
                vm.searchResults = response.insureds;
           }
       });
}

How would I stub the promise so that when I call getInsureds it would resolve the promise and return me the results immediately. I started like this (jasmine test), but I am stuck, as I don't know how to resolve the promise and pass in arguments needed.

it("search returns over 100 results searchResults should contain only 100 records ", function () {

    var results103 = new Array();

    for (var i = 0; i < 103; i++) {
        results103.push(i);
    }

    var fakeSearchForm = { $valid: true };
    var isSearchValidStub = sinon.stub(sut, "isSearchCriteriaValid").returns(true);

    var deferred = $q.defer();
    var promise = deferred.promise;
    var dsStub = sinon.stub(inSearchDataSvc, "getInsureds").returns(promise);

    var resolveStub = sinon.stub(deferred, "resolve");

    //how do i call resolve  and pass in results103

    sut.performSearch(fakeSearchForm);

    sinon.assert.calledOnce(isSearchValidStub);
    sinon.assert.calledOnce(dsStub);

    sinon.assert.called(resolveStub);

    expect(sut.searchResults.length).toBe(100);

});

Answer

Yu Huang picture Yu Huang · May 26, 2017

At current sinon version v2.3.1, you can use stub.resolves(value) and stub.rejects(value) function

For example, you can stub myClass.myFunction with following code

sinon.stub(myClass, 'myFunction').resolves('the value you want to return');

or

sinon.stub(myClass, 'myFunction').rejects('the error information you want to return');