Jasmine unit tests failing due to unknown provider error

Jasmine Unit Tests Failing Due to Unknown Provider Error

The “Unknown provider” error in Jasmine unit tests typically occurs when AngularJS cannot locate or resolve a service, factory, or other dependency that is injected into your component, controller, or service. This happens most often during the setup phase of unit tests when dependencies are not correctly mocked or configured.

In this article, we’ll explore how to troubleshoot and fix the “Unknown provider” error in Jasmine unit tests and ensure that your dependencies are properly injected.

---

Common Causes of the “Unknown Provider” Error

1. Missing Service/Factory in module Configuration One of the most common causes is when the service or factory being tested is not properly included in the module configuration. Solution: Ensure that the service or factory is correctly registered in the module, both in your application code and in the unit test configuration. Example: // Example service angular.module('app').service('myService', function() { this.getData = function() { return 'data'; }; }); // Unit test configuration describe('MyController', function() { var $controller, $rootScope, myService; beforeEach(angular.mock.module('app')); // Ensure the module is included beforeEach(inject(function(_$controller_, _$rootScope_, _myService_) { $controller = _$controller_; $rootScope = _$rootScope_; myService = _myService_; // Inject the service })); it('should call getData on myService', function() { var controller = $controller('MyController'); expect(myService.getData()).toBe('data'); }); });
2. Incorrect Dependency Injection in the Controller or Service If the controller or service does not have its dependencies properly injected, you might see the “Unknown provider” error. This typically occurs if you are trying to inject a service into a controller without properly configuring it in the inject function of the test. Solution: Ensure that the dependencies are correctly injected in the test setup, and check the names of your dependencies to ensure that they match. Example: // Controller angular.module('app').controller('MyController', function(myService) { var vm = this; vm.data = myService.getData(); }); // Test setup describe('MyController', function() { var $controller, $rootScope, myService; beforeEach(angular.mock.module('app')); // Ensure the module is included beforeEach(inject(function(_$controller_, _$rootScope_, _myService_) { $controller = _$controller_; $rootScope = _$rootScope_; myService = _myService_; // Inject the service })); it('should call getData on myService', function() { var controller = $controller('MyController'); expect(controller.data).toBe('data'); }); });
3. Module Dependencies Not Mocked in Unit Tests Sometimes the service you’re testing may depend on other services or modules that are not included in the test configuration. If the dependencies are not mocked or provided in the test setup, you might encounter the “Unknown provider” error. Solution: If your service or controller depends on another service or module, make sure to include or mock those dependencies in your unit test. Example: angular.module('app').service('myService', function($http) { this.getData = function() { return $http.get('/api/data'); }; }); describe('MyService', function() { var myService, $httpBackend; beforeEach(angular.mock.module('app')); // Ensure the module is included beforeEach(inject(function(_myService_, _$httpBackend_) { myService = _myService_; $httpBackend = _$httpBackend_; })); it('should return data from the API', function() { var mockData = { name: 'Test' }; $httpBackend.whenGET('/api/data').respond(mockData); var data; myService.getData().then(function(response) { data = response.data; }); $httpBackend.flush(); expect(data).toEqual(mockData); }); });
4. Incorrect Module Loading Order AngularJS modules have to be loaded in the correct order to ensure that all dependencies are available when needed. If you try to inject a service or factory before the module that registers it has been loaded, you will see the “Unknown provider” error. Solution: Ensure that you load the modules in the correct order in the test setup. Always use angular.mock.module() to load the module in the test setup before injecting any dependencies. Example: describe('MyController', function() { var $controller, myService; beforeEach(angular.mock.module('app')); // Ensure the app module is loaded first beforeEach(inject(function(_$controller_, _myService_) { $controller = _$controller_; myService = _myService_; // Inject the service })); it('should inject the service correctly', function() { var controller = $controller('MyController'); expect(controller.myService).toBeDefined(); }); });
5. Service Not Registered in the Module If the service is not registered correctly in your AngularJS module, it will cause the “Unknown provider” error. Ensure that the service is properly registered before you attempt to inject it. Solution: Double-check the service registration to ensure it’s included in the module’s configuration. Example: angular.module('app', []) .service('myService', function() { this.getData = function() { return 'data'; }; });

---

Steps to Fix the “Unknown Provider” Error

1. Ensure Module is Loaded: Always load the module in your test setup using angular.mock.module('app'). Ensure that the module is correctly registered in your application.
2. Check Dependency Injection: Verify that you are correctly injecting the dependencies in the beforeEach(inject(...)) function.
3. Mock Dependencies: If your service or controller relies on other services, mock those services in your test to avoid triggering the “Unknown provider” error.
4. Correct Registration: Ensure that the service or factory is properly registered in your AngularJS module before it is used in your tests.
5. Review Provider Names: Check for any typos in the provider names or variable names in your inject calls.