I have a functional component that displays something that has been dispatched to the redux-store. In Jest I'm trying to use the same implementation (reducers) in the tests I am using in the application. My Test looks like this:

import { render, screen } from '@testing-library/react';
import { Provider } from 'react-redux';
// eslint-disable-next-line import/no-extraneous-dependencies
import { applyMiddleware, createStore } from 'redux';
import ReduxThunk from 'redux-thunk';
import reducer from '../../utils/reducers';
import { initialState } from '../../index';
import Paragraph from '../../components/document/paragraph/Paragraph';

const author = () => ({
  id: '5bbab532-e546-4cf6-957a-823948baa416',
  name: 'Unknown',
  image: null,
});

const paragraph = () => ({
  id: '5bbab532-e546-4cf6-957a-823948baa417',
  ordinal: 1,
  content: '',
  author: author(),
});

const mockStore = () => {
  const unknown = author();
  // eslint-disable-next-line max-len
  const s = createStore(reducer, initialState(unknown.id, unknown.name, unknown.image), applyMiddleware(ReduxThunk));
  console.log(s.getState());
  return s;
};

let store;
describe('Test paragraph', () => {
  beforeEach(() => {
    store = mockStore();
  });

  it('Is rendered', () => {
    const p = paragraph();
    store.dispatch({ type: 'ADD_PARAGRAPH', p });
    render(
      <Provider store={store}>
        <Paragraph id={p.id} />
      </Provider>,
    );
    expect(screen.getByText(/author/i)).toBeInTheDocument();
    expect(screen.getByText(/locked-by/i)).toBeInTheDocument();
  });
});

The store looks like this before it is given to the provider:

{
  isAuthenticated: false,
  author: {
    id: '5bbab532-e546-4cf6-957a-823948baa416',
    name: 'Unknown',
    image: null
  },
  otherAuthors: [],
  paragraphs: [ undefined ],
  messages: [ 'ADD_PARAGRAPH' ],
  error: { isPresent: false, message: '' }
}

Because of the paragraphs: [ undefined ] I get this error in the component to test: const paragraph = useSelector((state) => state.paragraphs.find((p) => id === p.id));. Why is it undefined and how can I fix this?