Angular 7 testing: "Can't bind to formGroup since it isn't a known property of form"

It depends on which type of form you are using in your project. Angular provides Template-driven forms and Reactive forms. If you are using Reactive forms then, You need to import ReactiveFormsModule in your componentName.spec.ts file as

import { ReactiveFormsModule } from '@angular/forms';
beforeEach(async(() => {
TestBed.configureTestingModule({
  declarations: [ ContactUsFormComponent ],
  imports: [ReactiveFormsModule]
})
.compileComponents();}));

Otherwise, if you are using Template driven forms then, you need to import FormsModule.