What causes "Cannot configure the test module when the test module has already been instantiated"?

Question

here is my test :

describe('ValueService', () => {

  it('#getValue should return real value', () => {
    expect(true).toBeTruthy();
  });
});

And I have this error :

Failed: Cannot configure the test module when the test module has already been instantiated. Make sure you are not using inject before R3TestBed.configureTestingModule. Error: Cannot configure the test module when the test module has already been instantiated. Make sure you are not using inject before R3TestBed.configureTestingModule.

Answer 1

Please note that you may experience this error if the following conditions are true, even if you properly have your TestBed.configureTestingModule inside a describe:

1. Your project is on Angular 13+
2. You are using NgRx
3. You are using provideMockStore in your test.

This issue is discussed here.

The fix is to add teardown: { destroyAfterEach: false } to your module configuration.