test.js

import React from 'react';
import { JSDOM } from 'jsdom';
const { document } = new JSDOM('').window;

function App() {
  const [count, setCount] = useState(false);
  const [error, setError] = useState(null);

  const subtract = () => setCount(count - 1);
  const add = () => setCount(count + 1);

  return (
    <div>
      <h1>Example</h1>

      <button onClick={subtract}>-</button>
      {count}
      <button onClick={add}>+</button>

      {error && <p>Oops!</p>}
    </div>
  );
}

function useState(initial) {
  return [initial, () => {}];
}

function ReactDOMRender(element, rootNode) {
  const node = recurseTree(element);
  rootNode.appendChild(node)
}

function recurseTree(element, parent) {
  if (element && typeof element.type === 'function') {
    return recurseTree(element.type(element.props), parent);
  }

  let node;

  if (element === null) {
    node = document.createComment('empty');
  } else if (typeof element !== 'object') {
    node = document.createTextNode(element);
  } else {
    node = document.createElement(element.type);
    const { children } = element.props;

    if (children) {
      const childElements = Array.isArray(children) ? children : [children];

      childElements.forEach(child => {
        recurseTree(child, node);
      });
    }
  }

  if (parent) {
    parent.appendChild(node);
  }

  return node;
}

////////////////////////////////////////////////////////////
const root = document.createElement('div')
ReactDOMRender(<App />, root);