Angular 8 testing error Unexpected value 'DecoratorFactory' imported by the module 'DynamicTestModule' - karma-jasmine

Question

I am trying to make Jasmine & Karma framework into the current angular application running in ver 8.2. But i am coming across this weird error inside the Karma test running window:
Failed: Unexpected value 'DecoratorFactory' imported by the module 'DynamicTestModule'. Please add a #NgModule annotation.
What is the problem?
My componenent.spec.ts looks like this:
import { async, ComponentFixture, TestBed } from '#angular/core/testing';
import { HomeComponent } from './home.component';
import { NO_ERRORS_SCHEMA} from '#angular/core';
import {RouterTestingModule} from '#angular/router/testing';
import {HttpClientTestingModule} from '#angular/common/http/testing';
import { MsalService } from '#azure/msal-angular';
import { Store } from '#ngrx/store';
import { Pipe } from '#angular/core';
describe('HomeComponent', () => {
let component: HomeComponent;
let fixture: ComponentFixture<HomeComponent>;
beforeEach(async(() => {
TestBed.configureTestingModule({
imports: [RouterTestingModule, HttpClientTestingModule, Pipe]
,declarations: [HomeComponent]
,schemas:[NO_ERRORS_SCHEMA]
,providers: [
{provide: MsalService, useFactory: '' },
{provide: Store, useFactory: '' }
]
})
.compileComponents();
}));
it('should have header text', async(() => {
const fixture = TestBed.createComponent(HomeComponent);
fixture.detectChanges();
const compiled = fixture.debugElement.nativeElement;
//expect(compiled.querySelector('.header-txt').textContent).toContain('Tax');
}));
});

Answer 1

I found the cause :-
export class MockStore<T> {
private state: BehaviorSubject<T> = new BehaviorSubject(undefined);
setState(data: T) { this.state.next(data); }
select(selector?: any): Observable<T> {
return this.state.asObservable();
}
pipe() {}
dispatch(action: any) { }
}
========================================================================
TestBed.configureTestingModule({
{provide: Store, useFactory: 'MockStore' }
..............
The useFactory property must be some custom class name. Now i mocked the store class.