test-renderer.js

import React from 'react';
import TestRenderer from 'react-test-renderer';

const Text = (props) => <p>{props.children}</p>;

const App = () => (
  <section>
    <h1>Hello</h1>
    <Text>hogehoge</Text>
  </section>
);

const renderer = TestRenderer.create(<App />);
renderer.toJSON();
// {"type":"section","props":{},"children":[{"type":"h1","props":{},"children":["Hello"]},{"type":"p","props":{},"children":["hogehoge"]}]}