Executing a mock action when initializing a controller in AngularJS during testing

Question

Executing a mock action when initializing a controller in AngularJS during testing

My AngularJS controller is structured as follows:

app.controller('MyCtrl', function($scope, service) {

  $scope.positions = service.loadPositions(); // this invokes $http internally

  $scope.save = function() {
    ...
  };

  // other $scope functions here

});

Whenever I write a test for any of the methods in $scope, I find that I need to stub service.loadPositions() each time:

it('should save modified position', function($controller, service, $rootScope) {
    spyOn(service, 'loadPositions').andReturn(fakeData);

    var scope = $rootScope.$new();
    $controller('MyCtrl', {$scope: scope});

    // testing logic here
})

Is there a way to avoid repeating this stubbing process in every test? Once I have tested that an action is invoked on controller start, do I really need to stub it again in each subsequent test? This repetition is becoming cumbersome.

EDIT

I came across ngInit and thought I could utilize it for this purpose, but it seems to be not recommended. I'm unsure why?

javascript testing angularjs

Answer 1

Answer №1

Implement a beforeEach function within your describe block:

describe('Testing Functionality', function() {
    var $controller,
        $rootScope,
        serviceMock;

    beforeEach(function() {
        serviceMock = { loadPositions: function() {} };
        spyOn(serviceMock, 'loadPositions').andReturn(fakeData);

        inject(_$controller_, _$rootScope_) {
            $rootScope = _$rootScope_.$new();
            $controller = _$controller_('MyCtrl',
                {$scope: $rootScope, service: serviceMock});
        };
    });

    it('should correctly save updated position', function() {       
        // run tests here
    });
});

Note that I have streamlined the controller setup process by moving it to the beforeEach function, eliminating the need to repeat it in every test case.

In case you are curious about the underscores used in the inject arguments, they allow for the creation of local variables like $controller and $rootScope. These underscores do not impact Angular's resolution of function dependencies.

Update: A minor error in the code example has been fixed.

Answer 2

Implement a beforeEach function within your describe block:

describe('Testing Functionality', function() {
    var $controller,
        $rootScope,
        serviceMock;

    beforeEach(function() {
        serviceMock = { loadPositions: function() {} };
        spyOn(serviceMock, 'loadPositions').andReturn(fakeData);

        inject(_$controller_, _$rootScope_) {
            $rootScope = _$rootScope_.$new();
            $controller = _$controller_('MyCtrl',
                {$scope: $rootScope, service: serviceMock});
        };
    });

    it('should correctly save updated position', function() {       
        // run tests here
    });
});

Note that I have streamlined the controller setup process by moving it to the beforeEach function, eliminating the need to repeat it in every test case.

In case you are curious about the underscores used in the inject arguments, they allow for the creation of local variables like $controller and $rootScope. These underscores do not impact Angular's resolution of function dependencies.

Update: A minor error in the code example has been fixed.

Answer 3

Answer №2

If you want to ensure that your fake service is always returned, consider moving it into the beforeEach() function and using $provide.

Assuming you don't have all of your test code, something like this should suffice:

var scope, controller;

beforeEach(module("app", function($provide){
    var mockedService = {
      loadPositions: function(){return fakeData;}//you can also use sinon here
    };

    $provide.value('service', mockedService);
});   
beforeEach(inject(function($rootScope, $controller) {
    scope = $rootScope.$new();
    controller = $controller;
}));

it('should save modified position', function() {


    controller('MyCtrl', {$scope: scope});

    // test your functionality here
});

Answer 4

If you want to ensure that your fake service is always returned, consider moving it into the beforeEach() function and using $provide.

Assuming you don't have all of your test code, something like this should suffice:

var scope, controller;

beforeEach(module("app", function($provide){
    var mockedService = {
      loadPositions: function(){return fakeData;}//you can also use sinon here
    };

    $provide.value('service', mockedService);
});   
beforeEach(inject(function($rootScope, $controller) {
    scope = $rootScope.$new();
    controller = $controller;
}));

it('should save modified position', function() {


    controller('MyCtrl', {$scope: scope});

    // test your functionality here
});

Executing a mock action when initializing a controller in AngularJS during testing

Answer №1

Answer №2

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