React Native Testing Library get by access role

Question

I am really newReact Native Testing Library. My app basically works like this: it fetched the data and display on my to my as Text format, I used jsonplace holder api. This is app-demo. I have have created one Text where I define test role="header". I want to test the Text, does it work properly under role="header". I make a fake data and try to test it. I can able target the role from the component but I don't how to get the expected data. I tried with toBe, getByText but each time I am getting error: TypeError: toBe is not function.

This is my app component

  const [state, setState] = React.useState([]);
  React.useEffect(() => {
    fetch("https://jsonplaceholder.typicode.com/todos/")
      .then((response) => response.json())
      .then((json) => setState(json));
  }, []);

  return (
    <View style={styles.container}>
      {state.map((i) => (
        <Text role:'header'>{i.title}</Text>
      ))}
    </View>
  );
}

This is my test suite

import React from 'react';

import { fireEvent, render, cleanup, act } from '@testing-library/react-native';

import Json from './Json';


describe('<Json/>', () => {
  afterEach(cleanup);

  test('get data properly', async () => {
    const component = <Json/>;
    const { getByA11yRole } = render(component);

    const header = await getByA11yRole('header');

    console.log(header);

    expect(header).toBe(/delectus aut autem/);
  });
});