After we’ve managed to help jasmine’s spies infiltrate a ‘real’ service that was injected with angular’s dependency-injection mechanism, it’s time to mess up with the DI itself.

Until now, before each test, we’ve declared:

beforeEach(angular.mock.module('MyModule'));

This is a call to angular.mock to set the “name space” for the injector. But this might not be enough… What if our tested service is using a module that we don’t have (or don’t want to have) access to in the tests? What if we have a service in our current module that we don’t want to instantiate (i.e. constructor is too heavy)?

Overriding dependencies

beforeEach(angular.mock.module(function($provide) {
    $provide.value('MyDataService', spyObj);
}));

So, what do we have here? We are using $provide(), telling angular to provide use with the spyObj when we ask for ‘MyDataService’. This is not something from ngMock, it’s core angular.

Here we are ‘creating’ a module configuration with angular, and registering it to the test scope using angular.mock.module(). When we call it after we’ve called another module() function, we override any previous definitions of a service with the same name. Now, our spyObj will be injected anywhere in the test scope, and angular won’t have the delight to construct an instance of ‘MyDataService’. Pay attentions that all module() functions must be called before any inject() functions.

Note:

We used $provide.value(), since we’ve already created the service instance.

You can use also $provide.service():

beforeEach(angular.mock.module(function($provide) {
    $provide.service('MyDataService', function(){
        return spyObj;
    });
}));