Injected Dependency is undefined in Unit Test

Question

I'm new to Angular and I'm not quite sure exactly how dependency injection works. My problem is that I have Service A which depends on Service B, but when I inject Service A into my test Service B becomes undefined.

I have seen Injecting dependent services when unit testing AngularJS services but that problem is a bit different than mine.

This Injected Dependencies become undefined in angular service is very similar to my issue but I couldn't translate the JS.

I have also changed my variable names and simplified the code to remove irrelevant lines.

Service.ts

export class ServiceA {
    constructor(private $resource: ng.resource.IResourceService, private ServiceBInstance: ServiceB){
    }

    ServiceAMethod() {
        var resources = ServiceBInstance.property;  //ServiceBInstance is undefined here
    }
}

factory.$inject = [
    '$resource'
    'ServiceBModule'
];
function factory($resource: ng.resource.IResourceService, ServiceBInstance: ServiceB): IServiceA {
    return new ServiceA($resource, ServiceBInstance);
}

angular
    .module('ServiceAModule')
    .factory('ServiceA',
    factory);

Spec.ts

describe('ServiceB', (): void => {

    beforeEach((): void => {
        angular.mock.module(
            'ServiceAModule',
            'ServiceBmodule',
            'ngResource'
        );
    });

    describe('ServiceAMethod', (): void => {

        it("should...", inject(
            ['ServiceA', (ServiceAInstance: ServiceA): void => {
                ServiceAInstance.ServiceAMethod(); //Problem Here
            }]));
    });

});

The problem I'm having is that when I call ServiceAMethod I get an error which states "TypeError: Cannot read property 'property' of undefined". The weird thing is that $resource is never undefined but my ServiceB is always undefined.

I thought that when I inject ServiceA into my test it should automatically also inject all of its dependencies.

Also note that I am not mocking ServiceB on purpose.

Update

I've also tried to inject an instance of my ServiceB into the it but when I print out the variable it also states that is it undefined, and when I try to to do the code below into the beforeEach

inject(function (_ServiceBInstance_: ServiceB) {
        console.log(_ServiceBInstance_);
    });

I get and Unknown Provider error.

Answer 1

Ok so after hours of searching I finally found the answer. I forgot to include a file which included Angular's .config method

When creating the provider make sure that you also call .config, here's an example:

angular
    .module('ServiceBModule')
    .config(['ServiceBProvider', (ServiceBClass) => { //Very Important
        //Code here
    }])
    .provider('ServiceB', ServiceB);