Provider not found when injecting in Angular unit tests?

Question

I have a service that receives a class in its constructor. I've mocked the injected service and added it as a provider both in the test module and overridden in the test component, but I'm still getting NullInjectorError: No provider for UserService!

Here's the test - please rest assured that I've imported everything that I need:

describe('DataConsentComponent', () => {
  let component: DataConsentComponent;
  let fixture: ComponentFixture<DataConsentComponent>;

  class UserMock extends User {

    constructor () {
      super();
    }
  }

  class UserServiceMock {

    constructor () {

    }
  }

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [DataConsentComponent],
      providers: [
        { provide: 'UserService', useClass: UserServiceMock },
        { provide: 'User', useClass: UserMock }
      ]
    });

    TestBed.overrideComponent(
      DataConsentComponent,
      {
        set: {
          providers: [
            { provide: 'UserService', useClass: UserServiceMock },
            { provide: 'User', useClass: UserMock }
          ]
        }
      });

    fixture = TestBed.createComponent(DataConsentComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();

  }));


  it('should create', inject([UserService], () => {
    expect(component).toBeTruthy();
  }));
});

And the class being tested:

import { Component, OnInit } from '@angular/core';
import { UserService } from '@team/user.service';
import { User } from '@team/user.model';
import { GDPR_IS_ACTIVE } from '../../config/constants';

@Component({
  selector: 'app-data-consent',
  template: ''
})

export class DataConsentComponent {

  public User: User;

  constructor(private UserService: UserService){
    this.UserService.UserSource$.subscribe(
      (User: ETMUser) => {
        this.User = User;
    });
  }

  getGDPRIsActive(): boolean {
    return GDPR_IS_ACTIVE() || false;
  }

  getIfUserIsClient() {
    return this.UserService.getUserIsClient();
  }

  getIfUserIsEmployee() {
    return this.UserService.getUserIsEmployee();
  }

  showCandidateGDPRInformation (candidate) {
    return true;
  }

  getNavigateLinkLabel(candidate):any {
    return 'View';
  }

  shouldShowNavigate(candidate) {
    return true;
  }

  isSelectable(candidate) {
    return true;
  }

}

If there's a better way to get that service in, I'm more than willing to refactor.

Answer 1

Removing the single quotes around the service names in the providers array in your unit test should do the trick.

You want the TestBed to provide them as classes/objects, not strings, or tokens.