Challenges encountered when unit testing ngx-translate

0

I am encountering issues with unit testing while using the ngx-translate library. Despite adding a provider for TranslateService, the tests keep asking for more providers, creating an endless loop of dependencies.

Specifically, I am trying to unit test my auth component, which relies on the translate service in its constructor.

Even after including TranslateService as a provider (as shown below), it continues to request additional dependencies from translate. It seems like there must be a different solution to this problem.

  providers:[
    TranslateService
  ]

Here is an image showcasing the error:

app.module

return new TranslateHttpLoader(http);
}

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    ...
    TranslateModule.forRoot({
      loader: {
        provide: TranslateLoader,
        useFactory: HttpLoaderFactory,
        deps: [HttpClient]
       },
    defaultLanguage: 'en'
    })
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

It's worth noting that the sharedModule already exports the TranslateModule used across the app.

Shared Module

@NgModule({
  imports: [
    ...,
    TranslateModule,
  ],
  exports: [
    ...,
    TranslateModule
  ],
  providers:[
  ]
})
export class SharedModule { }

The auth component is also part of a lazy module.

auth.module

@NgModule({
  declarations: [
    AuthComponent
  ],
  imports: [
    CommonModule,
    AuthRoutingModule,
    SharedModule
  ]
})
export class AuthModule { }

auth.component.ts

export class AuthComponent implements OnInit { 

  constructor(public translate: TranslateService)
}

Spec.ts

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

  beforeEach(async () => {
    await TestBed.configureTestingModule({
      imports:[
        HttpClientTestingModule,
        SharedModule,
      ],
      providers:[
        TranslateService,
      ],
      declarations: [ AuthComponent ],
      schemas: [CUSTOM_ELEMENTS_SCHEMA, NO_ERRORS_SCHEMA]
    })
    .compileComponents();
  });

  beforeEach(() => {
    fixture = TestBed.createComponent(AuthComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });

Any suggestions on resolving this issue?

Answer №1

To properly test the `AuthComponent`, you can mock the `TranslateService` along with its required methods and properties. Here's how you can do it:

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

  beforeEach(async () => {
    await TestBed.configureTestingModule({
      imports:[
        HttpClientTestingModule,
        SharedModule,
      ],
      providers:[
        // !! Mock the TranslateService
        { provide: TranslateService, useValue: { /* Implement mock behaviors here */} }
      ],
      declarations: [ AuthComponent ],
      schemas: [CUSTOM_ELEMENTS_SCHEMA, NO_ERRORS_SCHEMA]
    })
    .compileComponents();
  });

  beforeEach(() => {
    fixture = TestBed.createComponent(AuthComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });

For more information on mocking external dependencies, please refer to:

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