http://stackoverflow.com/q/39895888/2587435

something.ts

  it('can call I18n.get.', async(() => {
    comp.content.nativeElement.innerHTML = 'nope';
    comp.key = 'my-key';
    comp.domain = 'StackOverflowDomain';
    comp.ngOnChanges();
    fixture.whenStable().then(() => {
      fixture.detectChanges();
      // fixture.detectChanges();
      expect(comp.text).toBe('hello');
    });
    // comp.ngOnChanges();
    // tick(1000);
  }));