省去繁重工作，构建 UI

import React from 'react';
import { render, unmountComponentAtNode } from 'react-dom';
import { act } from 'react-dom/test-utils';
import { composeStories } from '@storybook/testing-react';
import * as stories from './UserCard.stories';

// Compile the "MissingProfileImage" story
const { MissingProfileImage } = composeStories(stories);

let container = null;
beforeEach(() => {
  container = document.createElement('div');
  document.body.appendChild(container);
});

afterEach(() => {
  unmountComponentAtNode(container);
  container.remove();
  container = null;
});

it('renders a fallback profile image', () => {
  // Render the story
  act(() => {
    render(<MissingProfileImage />, container);
  });

  // Verify the DOM structure
  expect(container.querySelector('img').getAttribute('src'))
    .toEqual(
      '/images/user-fallback.png'
    );
});