ngx-translate: Translate string in Unit Testing

Question

I can get the value if it's a static test, but whenever I'm trying to get the translated value (using ngx-translate), it's empty.

<div id="header-title">
    <h1>{{ 'MENU_TITLE' | translate | uppercase }}</h1>
</div>

This works and returns Test

<div id="header-title">
    <h1>Test</h1>
</div>

spec.ts

it('should translate a string using the key value', () => {
    fixture = TestBed.createComponent(NavComponent);
    const title = fixture.nativeElement;
    console.log(title.querySelector('#header-title h1').innerHTML);
});

Importing translate module

beforeEach(async(() => {
        TestBed.configureTestingModule({
            imports: [RouterTestingModule,
                TranslateModule.forRoot({
                    loader: {
                        provide: TranslateLoader,
                        useFactory: HttpLoaderFactory,
                        deps: [HttpClient]
                    }
                }),
                HttpClientModule
            ],
            declarations: [NavComponent]
        }).compileComponents();

        injector = getTestBed();
        translate = injector.get(TranslateService);
    }));

-----FIXED----- but not sure if this is the right way to do

let fixture: ComponentFixture<NavComponent>;

it('should translate a string using the key value', () => {
    fixture.detectChanges() // fixture = TestBed.createComponent(NavComponent);
    const title = fixture.nativeElement;
    console.log(title.querySelector('#header-title h1').innerHTML);
});

Anderer

Add full example! – Clea

Answer 1

Found a solution to translate a key in Unit Testing

First you check if your textContent equals the translate key. Then you set a translation for that key and check again if it translated:

it('should translate a string using the key value', async(() => {
    fixture.detectChanges();
    const compiled = fixture.debugElement.nativeElement;
    expect(compiled.querySelector('#header-title h1').textContent).toEqual('MENU_TITLE');
    translate.setTranslation('en', { MENU_TITLE: 'reporting' });
    translate.use('en');
    fixture.detectChanges();
    expect(compiled.querySelector('#header-title h1').textContent).toEqual('REPORTING');
}));

Anderer

What will be the import for translate.setTranslation ? – Fillbert

Answer 2

Not sure why you would want to test this for a unit test.

The reason it doesn't work is that the translate pipe is async with the log happening while it is still retrieving the value.

I am going to assume you are already providing the TranslateModule in the TestBed.

Now, I am not sure if this will 100% work, so maybe you can give it a go. However, in theory, you can try using async and whenStable():

  it(
    'should translate a string using the key value',
    async(() => {
      fixture = TestBed.createComponent(NavComponent);
      const title = fixture.nativeElement;

      fixture.whenStable().then(() => {
        fixture.detectChanges();
        console.log(title.querySelector('#header-title h1').innerHTML);
      });
    })
  );

Good luck :)!

Alimentation

Thanks, it didn't work. However when I remove in fixture = TestBed.createComponent(NavComponent); in my code and replace it with fixture.detectChanges();.. This returns 'MENU_TITLE' still not what I want because I need the translation, but at least it's not empty anymore. Not sure if my workaround is the good way though – Anderer

Can I please see how you are providing the translate module? You must provide the loader so it knows where to get the translations (the same way you provide it in the app.module.ts. For more information: github.com/ngx-translate/core/issues/636 – Alimentation

Added in the question – Anderer