modeling-app/src/App.test.tsx

import React from "react";
import { render, screen } from "@testing-library/react";
import App from "./App";

let listener: ((rect: any) => void) | undefined = undefined;
(global as any).ResizeObserver = class ResizeObserver {
  constructor(ls: ((rect: any) => void) | undefined) {
    listener = ls;
  }
  observe() {}
  unobserve() {}
  disconnect() {}
};

test("renders learn react link", () => {
  render(<App />);
  const linkElement = screen.getByText(/viewer/i);
  expect(linkElement).toBeInTheDocument();
});