Jasmine Angular 9 test failing because 'unreachable' stack trace at injectableDefOrInjectorDefFactory

Question

I created an Angular application under 4. I have migrated from version to version and am currently latest version 9. I was reviewing my tests. I have a Login component that I had 3 working tests and now all are failing. It is now returning the following:

LoginComponent should be created ...
Failed: unreachable
Error: unreachable
    at injectableDefOrInjectorDefFactory (http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:17302:1)
    at providerToFactory (http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:17402:1)
    at providerToRecord (http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:17349:1)
    at R3Injector.processProvider (http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:17165:1)
    at http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:17144:1
    at http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:1400:1
    at Array.forEach (<anonymous>)
    at deepForEach (http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:1400:1)
    at R3Injector.processInjectorType (http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:17140:1)
    at http://localhost:9876/_karma_webpack_/node_modules/@angular/core/__ivy_ngcc__/fesm2015/core.js:16881:1

The Jasmine test is as following:

// File: login.component.spec.ts
import { async, ComponentFixture, TestBed, inject, fakeAsync, tick } from '@angular/core/testing';
import { FormsModule, ReactiveFormsModule, NgForm } from '@angular/forms';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { of, throwError } from 'rxjs';
import { SelectItem } from 'primeng/api';
import { Dialog } from 'primeng/dialog';
import { Header, Footer } from 'primeng/api';
import { ButtonModule } from 'primeng/button';
//
import { AlertsService } from '../../global/alerts/alerts.service';
import { UserService } from '../../net-incident/services/user.service';
import { AuthService } from '../../net-incident/services/auth.service';
import { LoginComponent } from './login.component';
import { ServerSelectionWindowComponent } from '../../net-incident/server-selection-window/server-selection-window.component';
//
describe('LoginComponent', () => {
    let sut: LoginComponent;
    let fixture: ComponentFixture<LoginComponent>;
    let alertService: AlertsService;
    const authServiceSpy = jasmine.createSpyObj('AuthService',
            ['authenticate', 'logout', 'isLoggedIn', 'isLoggedOut']);
    const userServiceSpy = jasmine.createSpyObj('UserService',
            ['emptyUser', 'getUser', 'getUserServer']);
    //
    beforeEach(async(() => {
        TestBed.configureTestingModule({
            imports: [
                FormsModule,
                ButtonModule,
                BrowserAnimationsModule
            ],
            declarations: [
                LoginComponent,
                Dialog,
                Header,
                Footer,
                ServerSelectionWindowComponent
            ],
            providers: [
                { provide: AlertsService, useClass: AlertsService },
                { provide: AuthService, useValue: authServiceSpy },
                { provide: UserService, useClass: userServiceSpy }
            ]
        } );
        alertService = TestBed.get( AlertsService );
        TestBed.compileComponents();
    }));
    beforeEach(() => {
        fixture = TestBed.createComponent(LoginComponent);
        sut = fixture.componentInstance;
        fixture.detectChanges();
    });
    it('should be created ...', () => {
        expect( sut ).toBeTruthy();
    });
});

Answer 1

providers: [
    ...
    { provide: UserService, useClass: userServiceSpy }
]

Should be changed to:

providers: [
    ...
    { provide: UserService, useValue: userServiceSpy }
]

Answer 2

For me I changed useClass for useValue. Like the example below:

TestBed.configureTestingModule({
      declarations: [...],
      imports: [...],
      providers: [
        { provide: PlansService, useClass: mockPlansService },
        { provide: AuthService, useClass: mockOAuthService }
      ]
    }).compileComponents();

For this

TestBed.configureTestingModule({
      declarations: [...],
      imports: [...],
      providers: [
        { provide: PlansService, useValue: mockPlansService },
        { provide: AuthService, useValue: mockOAuthService }
      ]
    }).compileComponents();

Answer 3

You can also create a mocked class to be used as your UserService:

class MockUserService {

  myMethod(): void {
    // mocked logic
  } 
}

describe('LoginComponent', () => {
...

providers: [
    ...
    { provide: UserService, useClass: MockUserService }
]
...

});