Jasmine: toHaveBeenCalled() returns undefined

As far as I understand, the .toHaveBeenCalled() Matcher of jasmine returns a Promise which is resolved when the function has been called. Actually for me, it returns undefined:

it('should show the first entries', () => {
  expect(contentfulService.first)
    .toHaveBeenCalled()
    .then(() => {
      expect(component.entries).toBe(entriesMock);
    });
});

The first method of the contentfulService is spied on like this:

contentfulService = TestBed.get(ContentfulService);
spyOn(contentfulService, 'first').and.callThrough();

The spec fails telling me:

TypeError: Cannot read property 'then' of undefined

I double checked it. It's definitely the result of toHaveBeenCalled() that returns undefined. Why? Am I getting something wrong?