Angular2, test directive, undefined-error

I'm trying to test a directive, called AceDirective (I'm using the ace-editor). So first I've build a TestComponent called MockSearchDirective which has got this directive:

@Component({
  selector: '[testAce]',
  directives: [AceDirective],
  template: '<div ace-editor></div>',
}) class TestAce {}

class MockSearchDirective {
}

Now if got my beforeEach and beforeEachProviders with the needed Injections:

beforeEachProviders( () => [
  provide(SearchDirective, {useClass: MockSearchDirective}),
  TestComponentBuilder,
  provide(DataTransportService, {useClass: MockDataTransportService}),
]);

beforeEach( inject( [TestComponentBuilder], (_tcb : TestComponentBuilder) => {
  this.searchDirective = new MockSearchDirective();
  this._dataTransportService = new MockDataTransportService();
  _tcb
   .createAsync(TestAce)
   .then( (fixture : ComponentFixture<TestAce>)=> {
     console.log(fixture);
     this.fixture = fixture;
   });
}));

This console.log prints the correct fixture containing the Ace-Editor. But, in the specific test:

it('Check if editor will be initiated correctly', (done) => {
  console.log(this.fixture);
  // let testAce = this.fixture.componentInstance;
  // let element = this.fixture.nativeElement;//.querySelector('div')
  // let elementRef = this.fixture.elementRef;

  //editor exists
  expect(this.fixture.elementRef).toBeDefined();
  done();
});

It fails. The console.log says, that this.fixture is undefined.

I also tried to inject the TextComponentBuilder in the test (and not via beforeEach):

  it('Check if editor will be initiated correctly', inject( [TestComponentBuilder], (_tcb : TestComponentBuilder) => {
  _tcb
   .createAsync(TestAce)
   .then( (fixture : ComponentFixture<TestAce>)=> {
     console.log(fixture);
     // let testAce = this.fixture.componentInstance;
     // let element = this.fixture.nativeElement;//.querySelector('div')
     // let elementRef = this.fixture.elementRef;

     //editor exists
     expect(fixture.elementRef).toBeDefined();
   });
}));

but then I've got some timeout:

zone.js:461 Unhandled Promise rejection: 'expect' was used when there was no current spec, this could be because an asynchronous test timed out

Does anyone know this error? And how to deal with it?

Thanks!