Angular 2 unit testing – getting error Failed to load ‘ng:///DynamicTestModule/module.ngfactory.js’

I ran into this issue myself yesterday. The problem was that I had an Input() property on my component class that I wasn’t setting in the test. So for example, in my-component.ts:

@Component({
  selector: 'my-component'
})
export class MyComponent {
  @Input() title: string;
}

and my-component.spec.ts:

beforeEach(() => {
  fixture = TestBed.createComponent(MyComponent);
  component = fixture.componentInstance;
  component.title="Hello there!" // <-- this is required!
  fixture.detectChanges();
});

Or you could provide a default value in the component somewhere. Either way, the test will crash if any inputs are not set and you’ll get that unintuitive error.

Note: Running ng test -sm=false will give the actual error message causing the problem. Credit: https://stackoverflow.com/a/45802115/61311