Jest enzyme test router with props

I have react application and started covering it with unit tests. My app file contains:

export default class App extends Component {
    render() {
        return (
  <Provider store={store}>
    <Router history={history}>      
        <div>
            <Header />
            <Switch>
              <Route exact path="/" component={Home} />
              <Route exact path="/detail/:collectionName/:RecordId/:firmId" component={DetailDialog} />
              <Route exact path="/dashboard" component={Dashboard} />
              <Route path="/auth-login" component={LogIn} />
              <Route path="/auth-register" component={Register} />
              <Route path="/user-manager" component={this.props.decoded.role==='Admin' ? Admin : Home} />
            </Switch>
        </div>
    </Router>
  </Provider>
        );
    }
}

I want to make next test: go to login, check href and by href check component.

it.only('test right component is attached', () => {
        const wrapper = shallow(<Login loginUser={fn}/>);
        const registerLink = wrapper.find("[data-qa='sign-up']").props().href;
        const history = jest.fn();
        const props = {
            decoded: {role: 'Admin'}
        }
        const router = mount(
            <MemoryRouter initialEntries={[registerLink]}>
                <App history={history} {...props} />
            </MemoryRouter>
        );
        expect(router.find(Register)).toHaveLength(1);
    });

Until mounting everything is ok. But on mount I receive the next error:

console.error Error: Uncaught [Error: Unable to find node on an unmounted component.]

What am I doing wrong? How can I mount the component and check that Register is inside?