How to get an instance of structural directive to properly test if some value has been passed to it?

structural-directive.spec.ts

import { Component, Directive, Input, TemplateRef, ViewContainerRef } from '@angular/core';
import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { By } from '@angular/platform-browser';

const showReflection: any = {};

@Directive({ selector: '[appShow]' })
export class UnlessDirective {
  constructor(
    private templateRef: TemplateRef<any>,
    private viewContainer: ViewContainerRef,
  ) { }

  @Input() set appShow(show: boolean) {
    showReflection.show = show;

    if (show) {
      this.viewContainer.createEmbeddedView(this.templateRef);
    } else {
      this.viewContainer.clear();
    }
  }
}

@Component({
  template: `
    <h1>STRUCTURAL DIRECTIVE TEST</h1>
    <h2 *appShow="displayExtraHeader">Lorem ipsum</h2>
  `,
})
class StructuralDirectiveComponent {
  displayExtraHeader = true;
}

fdescribe('Structural Directive', () => {
  let component: StructuralDirectiveComponent;
  let fixture: ComponentFixture<StructuralDirectiveComponent>;
  let compiled: any;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [
        UnlessDirective,
        StructuralDirectiveComponent,
      ],
    })
      .compileComponents();
  }));

  beforeEach(() => {
    fixture = TestBed.createComponent(StructuralDirectiveComponent);
    compiled = fixture.debugElement.nativeElement;
    component = fixture.componentInstance;
  });

  it('should create', () => {
    expect(component).toBeTruthy();
  });

  describe('HTML', () => {
    beforeEach(() => {
      component.displayExtraHeader = false;
      fixture.detectChanges();
    });

    it('should render <h1>', () => {
      expect(compiled.querySelector('h1')).not.toBeNull();
    });
    it('should pass displayExtraHeader to appShow', () => {
      const directive1: any = fixture.debugElement.query(By.css('[appShow]'));
      const directive2: any = fixture.debugElement.query(By.directive(UnlessDirective));

      console.log(`>>> directive1`, directive1);
      console.log(`>>> directive2`, directive2);

      // directive1 and directive 2 are null
      // @TODO: how to get an instance of structural directive?

      expect(showReflection.show).toEqual(false);
    });
  });
});