Unit testing Angular 2 authGuard; spy method is not being called - unit-testing

Question

I'm trying to unit test my auth guard service. From this answer I was able to get this far, but now when I run the unit test for this, it says Expected spy navigate to have been called.
How to I get my spied router to be used as this.router in the service?
auth-guard.service.ts
import { Injectable } from '#angular/core';
import { Router, CanActivate } from '#angular/router';
#Injectable()
export class AuthGuardService {
constructor(private router:Router) { }
public canActivate() {
const authToken = localStorage.getItem('auth-token');
const tokenExp = localStorage.getItem('auth-token-exp');
const hasAuth = (authToken && tokenExp);
if(hasAuth && Date.now() < +tokenExp){
return true;
}
this.router.navigate(['/login']);
return false;
}
}
auth-guard.service.spec.ts
import { TestBed, async, inject } from '#angular/core/testing';
import { RouterTestingModule } from '#angular/router/testing';
import { AuthGuardService } from './auth-guard.service';
describe('AuthGuardService', () => {
let service:AuthGuardService = null;
let router = {
navigate: jasmine.createSpy('navigate')
};
beforeEach(() => {
TestBed.configureTestingModule({
providers: [
AuthGuardService,
{provide:RouterTestingModule, useValue:router}
],
imports: [RouterTestingModule]
});
});
beforeEach(inject([AuthGuardService], (agService:AuthGuardService) => {
service = agService;
}));
it('checks if a user is valid', () => {
expect(service.canActivate()).toBeFalsy();
expect(router.navigate).toHaveBeenCalled();
});
});
Replacing RouterTestingModule with Router like in the example answer throws Unexpected value 'undefined' imported by the module 'DynamicTestModule'.

Answer 1

Instead of stubbing Router, use dependency injection and spy on the router.navigate() method:
import { TestBed, async, inject } from '#angular/core/testing';
import { RouterTestingModule } from '#angular/router/testing';
import { Router } from '#angular/router';
import { AuthGuardService } from './auth-guard.service';
describe('AuthGuardService', () => {
beforeEach(() => {
TestBed.configureTestingModule({
providers: [AuthGuardService],
imports: [RouterTestingModule]
});
});
it('checks if a user is valid',
// inject your guard service AND Router
async(inject([AuthGuardService, Router], (auth, router) => {
// add a spy
spyOn(router, 'navigate');
expect(auth.canActivate()).toBeFalsy();
expect(router.navigate).toHaveBeenCalled();
})
));
});
https://plnkr.co/edit/GNjeJSQJkoelIa9AqqPp?p=preview

Answer 2

For this test, you can use the ReflectiveInjector to resolve and create your auth-gaurd service object with dependencies.
But instead of passing the actual Router dependency, provide your own Router class (RouterStub) that has a navigate function. Then spy on the injected Stub to check if navigate was called.
import {AuthGuardService} from './auth-guard.service';
import {ReflectiveInjector} from '#angular/core';
import {Router} from '#angular/router';
describe('AuthGuardService', () => {
let service;
let router;
beforeEach(() => {
let injector = ReflectiveInjector.resolveAndCreate([
AuthGuardService,
{provide: Router, useClass: RouterStub}
]);
service = injector.get(AuthGuardService);
router = injector.get(Router);
});
it('checks if a user is valid', () => {
let spyNavigation = spyOn(router, 'navigate');
expect(service.canActivate()).toBeFalsy();
expect(spyNavigation).toHaveBeenCalled();
expect(spyNavigation).toHaveBeenCalledWith(['/login']);
});
});
class RouterStub {
navigate(routes: string[]) {
//do nothing
}
}