Angular2 Inject ElementRef in unit test

I encounter Can't resolve all parameters for ElementRef: (?) Error using the mock from @gilad-s in angular 2.4

Modified the mock class to:

export class MockElementRef extends ElementRef {
  constructor() { super(null); }
}

resolves the test error.

Reading from the angular source code here: https://github.com/angular/angular/blob/master/packages/core/testing/src/component_fixture.ts#L17-L60
the elementRef of the fixture is not created from the mock injection. And in normal development, we do not explicitly provide ElementRef when injecting to a component. I think TestBed should allow the same behaviour.