The mock service is not being utilized, while the genuine service is successfully injected

Question

The mock service is not being utilized, while the genuine service is successfully injected

I have a question regarding testing a controller that relies on a service. During my test, I noticed that the actual service is being injected instead of the mock service that I defined using $provider.factory. Can anyone explain why this might be happening?

"use strict";

describe("contestantController", function () {
    var dataService, rootScope, scope, passPromise, contestantController;

    beforeEach(function(){
        module(function ($provide) {

            //mock service
            $provide.factory('contestantDataService', ['$q', function ($q) {
                function save(data){
                    if(passPromise){
                        return $q.when();
                    } else {
                        return $q.reject();
                    }
                }
                function getData() {
                    if (passPromise) {
                        return $q.when(smallDataSet());
                    } else {
                        return $q.reject();
                    }
                }
                return {
                    addContestant: save,
                    getContestants: getData,
                };
            }]);

        });

        module('contestantApp');
    });

    beforeEach(inject(function ($rootScope, $controller, contestantDataService) {
        rootScope = $rootScope;
        scope = $rootScope.$new();
        dataService = contestantDataService;

        spyOn(dataService, 'getContestants').and.callThrough();

        contestantController = $controller('contestantController', {
            $scope: scope,
            contestantDataService: dataService
        });
    }));

    it('should call getContestants method on contestantDataService on calling saveData', function () {

        passPromise = true;
        rootScope.$digest();

        expect(dataService.getContestants).toHaveBeenCalled();
        expect(scope.contestants).toEqual(smallDataSet());
    });

});

javascript angularjs jasmine

Answer 1

Answer №1

Although Tyler's solution may appear to be effective, the logic behind it is slightly flawed.

The purpose of the module() function is simply to register modules or module initialization functions for later use by the inject() function in initializing the Angular injector. This action does not establish a direct connection between the mock service and the module.

In your case, the issue lies in the order in which services are registered. By first registering a mock contestantDataService and then registering the contestantApp module (which already contains its own contestantDataService), you are essentially overwriting the initial mock registration. To fix this problem, you can resolve it by moving the module('contestantApp') call to the beginning of your code block.

This implies that the following two blocks of code are equivalent and will both serve their intended purpose...

beforeEach(function(){
  module('contestantApp');
  module(function ($provide) {
    ...
  });
);

and

beforeEach(function(){
  module('contestantApp', function ($provide) {
    ...
  });
);

Answer 2

Although Tyler's solution may appear to be effective, the logic behind it is slightly flawed.

The purpose of the module() function is simply to register modules or module initialization functions for later use by the inject() function in initializing the Angular injector. This action does not establish a direct connection between the mock service and the module.

In your case, the issue lies in the order in which services are registered. By first registering a mock contestantDataService and then registering the contestantApp module (which already contains its own contestantDataService), you are essentially overwriting the initial mock registration. To fix this problem, you can resolve it by moving the module('contestantApp') call to the beginning of your code block.

This implies that the following two blocks of code are equivalent and will both serve their intended purpose...

beforeEach(function(){
  module('contestantApp');
  module(function ($provide) {
    ...
  });
);

and

beforeEach(function(){
  module('contestantApp', function ($provide) {
    ...
  });
);

Answer 3

Answer №2

Shoutout to @Yunchi for pointing out my error.

Remember to call the module function before mocking the service contestantDataService.

Simply update your code like this,

//ensure contestantDataService is present in this module in your production environment.

var dataService, rootScope, scope, passPromise, contestantController;
beforeEach(function(){
    //Specify module name where we define the mockService
    module('contestantApp', function ($provide) {
        //mock service
        $provide.factory('contestantDataService', ['$q', function ($q) {
            function save(data){
                if(passPromise){
                    return $q.when();
                } else {
                    return $q.reject();
                }
            }
            function getData() {
                if (passPromise) {
                    return $q.when(smallDataSet());
                } else {
                    return $q.reject();
                }
            }
            return {
                addContestant: save,
                getContestants: getData,
            };
        }]);
    });
    beforeEach(inject(function ($rootScope, $controller, contestantDataService) {
         rootScope = $rootScope;
         scope = $rootScope.$new();
         dataService = contestantDataService;

         spyOn(dataService, 'getContestants').and.callThrough();
         //no need to manually inject to our controller now.
         contestantController = $controller('contestantController', {
             $scope: scope
     });
}));

Instead of using $provide.factory, consider utilizing $provide.value for unit testing. It simplifies ensuring that contestantDataService is an object with the required functions.

Check out these related questions for more insights,

Injecting a mock into an AngularJS service.

Mock a service in order to test a controller.

Here is the jsfiddle I just created.

Enjoy exploring! : )

Answer 4

Shoutout to @Yunchi for pointing out my error.

Remember to call the module function before mocking the service contestantDataService.

Simply update your code like this,

//ensure contestantDataService is present in this module in your production environment.

var dataService, rootScope, scope, passPromise, contestantController;
beforeEach(function(){
    //Specify module name where we define the mockService
    module('contestantApp', function ($provide) {
        //mock service
        $provide.factory('contestantDataService', ['$q', function ($q) {
            function save(data){
                if(passPromise){
                    return $q.when();
                } else {
                    return $q.reject();
                }
            }
            function getData() {
                if (passPromise) {
                    return $q.when(smallDataSet());
                } else {
                    return $q.reject();
                }
            }
            return {
                addContestant: save,
                getContestants: getData,
            };
        }]);
    });
    beforeEach(inject(function ($rootScope, $controller, contestantDataService) {
         rootScope = $rootScope;
         scope = $rootScope.$new();
         dataService = contestantDataService;

         spyOn(dataService, 'getContestants').and.callThrough();
         //no need to manually inject to our controller now.
         contestantController = $controller('contestantController', {
             $scope: scope
     });
}));

Instead of using $provide.factory, consider utilizing $provide.value for unit testing. It simplifies ensuring that contestantDataService is an object with the required functions.

Check out these related questions for more insights,

Injecting a mock into an AngularJS service.

Mock a service in order to test a controller.

Here is the jsfiddle I just created.

Enjoy exploring! : )

The mock service is not being utilized, while the genuine service is successfully injected

Answer №1

Answer №2

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