use-viewport-size.spec.tsx

import React from 'react';
import ReactDOM from 'react-dom';
import { act } from '@testing-library/react';
import { useViewportSize } from './use-viewport-size';
 
describe(' UseViewportSize', () => {
  it('should render successfully', () => {
    // Setup
    let container = document.createElement('div');
    document.body.appendChild(container);
 
    const App = () => {
      const size = useViewportSize();
      return <div>{JSON.stringify(size)}</div>;
    };
 
    act(() => {
      ReactDOM.render(<App />, container);
    });
 
    expect(container.textContent).toEqual('{"width":1024,"height":768}');
 
    // Teardown
    document.body.removeChild(container);
    container = null;
  });
});