TypeError: Cannot read property 'then' of undefined angularjs-grunt test

Question

I'm using $q service to make an async calls. I can't resolve 'then' and 'defer' in unit tests using karma.

The below is my controller code.

scope.filterUrls = [{url:'page1'}, {url: 'page2'}, {url:'page-error'}];

scope.bindFilters = function () {
angular.forEach(scope.filterUrls, function (data) {
    scope.getFilterData(data.url, '').then(function (result) {
      if (data.url === 'page1') {
        scope.moduleData.index = result.data;
      } else if (data.url === 'page2') {
        scope.moduleData.page2 = result.data;
      } 
     });
  });
}

scope.getFilterData = function (filterUrls, params) {
  // $q service object
  var deferred = q.defer();

  // regular ajax request
  http({
    method: 'GET',
    url: app.api.root + filterUrls,
    params: params
  })
      .success(function (result) {
        // promise resolve
        deferred.resolve(result);
      })
      .error(function (result) {
        // called asynchronously if an error occurs
        // or server returns response with an error status.
        deferred.reject('Erreur request : ' + result);
      });
  return deferred.promise;
};

test spec:

it('should call getFilterData() in bindFilters()', function () {
    spyOn(scope, 'getFilterData');
    scope.bindFilters();
    expect(scope.getFilterData).toHaveBeenCalled();
  });

I'm getting an error called "TypeError: Cannot read property 'then' of undefined".

How can I write an unit test for those two methods using karma.

Update:

1.how do we can test the success and error of scope.getFilterData()

2 .then function in scope.bindFilters() function.

Please help..

Solution

If you only need to find out whether getFilterData is called or not, try returning a fake promise by faking the function:

With jasmine 1.3, we could use andCallFake:

it('should call getFilterData() in bindFilters()', function () {
    spyOn(scope, 'getFilterData').andCallFake(function(){//replace with a fake function
        var deferred = $q.defer(); //assume that you already inject $q service in beforeEach and save it as a variable.
        return deferred.promise; //returns a fake promise
    });
    scope.bindFilters();
    expect(scope.getFilterData).toHaveBeenCalled();
  });

With jasmine 2.0, we could use and.callFake instead.

Another solution is to use andReturnValue and $q.when():

it('should call getFilterData() in bindFilters()', function () {
        spyOn(scope, 'getFilterData').andReturnValue($q.when());
        scope.bindFilters();
        expect(scope.getFilterData).toHaveBeenCalled();
      });

With jasmine 2.0, we could use and.returnValue instead.