NullInjectorError: No provider for Store

You can use the ngrx mock store:

import { provideMockStore } from '@ngrx/store/testing';

beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [provideMockStore({})],
    });
  });

You can define a specific state and pass it as method parameter.

if your service is referencing an ngrx store then you need to import the ngrx modules. I am making an assumption right now that you are doing that in your AppModule. You need to duplicate that in your TestBed module. I generally create a test ngrx module that does all that and then I can just import that in any spec file that references Store

As stated here

Add following to the specs.ts file:
// Add the import the module from the package 
import { StoreModule } from '@ngrx/store';

   // Add the imported module to the imports array in beforeEach 
   beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [
        StoreModule.provideStore({})
      ],
      declarations: [
        // The component that's being tested
      ]
    })
    .compileComponents();
  }));

And if you get error Property 'provideStore' does not exist on type 'typeof StoreModule use forRoot instead of provideStore. Also look here and here is similar question here.

Cheers!