Dynamically pass a FormGroup to a child component in a Karma test (Angular)

child-test-1.component.spec.ts

import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { ReactiveFormsModule, FormBuilder } from '@angular/forms';
import { CommonModule } from '@angular/common';

import { AppModule } from './app.module';
import { ChildComponent } from './child.component';

describe('StaticComponent', () => {
    let component: StaticComponent;
    let fixture: ComponentFixture<ChildComponent>;

    beforeEach(
        async(() => {
            TestBed.configureTestingModule({
                declarations: [
                    ChildComponent
                ],
                imports: [
                    CommonModule,
                    ReactiveFormsModule,
                    AppModule
                ]
            }).compileComponents();
        })
    );

    beforeEach(() => {
        fixture = TestBed.createComponent(ChildComponent);
        component = fixture.componentInstance;
        
        // error occurs at 36
        fixture.detectChanges();
    });

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